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The proposed study aimed to develop a topical gel containing azelaic acid (AZA)-based lyotropic liquid crystals (LLCs) for the treatment of acne vulgaris. AZA-based LLCs were optimized by varying Poloxamer-407 and polyvinyl alcohol concentration using a central composite design, which showed that both independent variables had a significant effect on the formulation. The highest desirable trial of AZA-based LLCs (Batch-7) containing 300 mg poloxamer-407 and 100 mg polyvinyl alcohol depicted the particle size, zeta potential, and entrapment efficiency of 184.2 nm, -16.1 mV, and 79.96 %, respectively. TEM images confirmed the globular vesicles of LLCs, and ATR-FTIR and DSC results confirmed the compatibility of formulation excipients. In vitro, the release of AZA, AZA-based LLCs, AZA-based LLC gel, and marketed gel showed a release of 23.29, 95.24, 91.07 and 59.88 %, respectively, after 24 h in phosphate buffer pH 6.8. Ex vivo release of AZA-based LLC gel displayed an 86.56 % release after 24 h. The antimicrobial activity of AZA-based LLC gel exhibited a comparable efficacy with marketed gel against Cutibacterium acnes, Staphylococcus epidermis and Staphylococcus aureus. The acute dermal irritation study indicated excellent safety and skin compatibility of AZA-based LLC gel without any erythema and edema. The dermatopharmacokinetic study displayed an enhanced drug retention for AZA-based LLC gel (146.121 ± 21.13 µg/cm 2 ) than marketed gel (58.58 ± 15.95 µg/cm 2 ) in the dermal layer, which would improve its therapeutic effect. These outcomes proved that AZA-based LLC gel has the potential to enhance skin penetration and retention for effective management of acne vulgaris., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Alternative plasticizers such as diisononyl-1,2-cyclohexanedicarboxylate (DINCH), di(2-ethylhexyl) terephthalate (DEHTP), and di(2-ethylhexyl) adipate (DEHA) are progressively replacing phthalates in many consumer and professional products because of adverse effects on reproduction associated with some phthalates. Human exposures to these phthalate substitutes can occur through ingestion, skin absorption and inhalation. Skin uptake can lead to greater concentration at the target organs compared to ingestion because the skin exposure route bypasses the first-pass effect. Skin absorption studies are almost absent for these alternative plasticizers. We therefore wanted first, to characterize skin absorption of a mixture containing DINCH, DEHA and DEHTP in vitro using a flow-through diffusion cell system with ex vivo human skin, quantifying their respective monoester metabolites (mono-isononyl-cyclohexane-1,2-dicarboxylate (MINCH), mono-2-ethylhexyl adipate (MEHA), mono-2-ethylhexyl terephthalate (MEHTP), respectively); second, to validate these results by exposing five human volunteers to this mixture on their forearm and quantifying the corresponding urinary metabolites (including the monoesters and their oxidation products). Our study showed that two of these alternative plasticizers, DEHTP and DINCH, did not permeate skin showing as quantifiable metabolite levels in vitro and only traces of DEHA were quantified as its monoester metabolite, MEHA. Permeation coefficient (Kp) 0.06 and 55.8*10 -7 cm/h for neat and emulsified DEHA, respectively, while the permeation rate (J) remained low for both (0.005 and 0.001 µg/cm 2 /h, respectively). Participants exposed to a mixture of these three plasticizers did not have noteworthy urinary concentrations of their respective metabolites after 24 hours post-application. However, the alternative plasticizer mixture was completely absorbed after six hours post-application on the forearms of the human volunteers, and the urinary elimination curves showed a slight increase after 24 hours post-application. Further studies on skin absorption of these substances should follow the urinary elimination kinetics of these metabolites more than 24 hours post-application. We also recommend quantifying the parent compounds in the in vitro diffusion experiments., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Phthalates and other plasticizers are detected in high amounts in the indoor environment and therefore house dust can be an exposure source. Especially children have a relatively high unintended uptake of house dust, thus a higher exposure to plasticizers compared to adults may be possible. As accurate as possible exposure assessment data of the oral bioavailability of these compounds are necessary, however only one in vivo study with piglets is available so far. The aim of this study was to examine the oral bioavailability of phthalates and DINCH® in humans, which occur in typical house dust samples. We focused on the high molecular weight phthalates DEHP and DINP and their substitute DINCH®. Eleven volunteers ingested 6 g of house dust sieved to 2 mm. The urine was collected over a period of 36 h. The excreted plasticizers metabolites were quantified by an LC-MS/MS method. The mean recovery of urine metabolites was 51 % ± 20 % for DEHP, 26 % ± 13 % for DINP and 19 % ± 6% for DINCH® based on the parent compounds administered as dust samples. The metabolites of DEHP, DINP and DINCH® reached their maximum concentration after 2-19 hours post dose in urine. The bioavailability of DEHP was in agreement among the different dust samples. For DEHP, we were able to confirm previous findings from the oral bioavailability study with piglets and we could not observe a significant difference between the dust particle size (65 μm vs 2 mm) and the bioavailability. Considering the observed bioavailability, an estimated dust intake of 50 mg/d for toddlers can substantially contribute to the total plasticizer exposure., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests, (Copyright © 2021. Published by Elsevier B.V.)

Introduction : Bempedoic acid is a first-in-class low-density lipoprotein cholesterol (LDL-C) lowering agent which offers an important opportunity for further LDL-C lowering in statin-intolerant patients or in patients requiring further LDL-C reduction despite maximally tolerated statin therapy. Areas covered : In this review, we examined the pharmacodynamics, pharmacokinetics, clinical efficacy, and safety of bempedoic acid, based on randomized clinical phase III clinical studies and their meta-analyses. Expert opinion : Unlike statins, bempedoic acid is administered as a prodrug and is converted to active form by a liver-specific enzyme. For the liver-specific mechanism of action, bempedoic acid has the potential to reduce the risk of muscle-related adverse events which can limit the utilization and effectiveness of statin therapy.

Bempedoic acid acts by inhibiting adenosine triphosphate-citrate lyase (ACL) and consequently cholesterol biosynthesis, leading to increased expression of LDL receptors and increasing low-density lipoproteins (LDL-C) plasma clearence. It is a prodrug for oral administration with intracellular activation. It is activatedin liver cells and to a lesser extent in kidney cells, being absent in adipose tissue and muscle cells. Therefore, unlike statins, its potential myotoxic effect is very limited. It has recently been approved as a lipid-lowering drug in combination with diet, with statins, or with other lipid-lowering drugs in patients with hypercholesterolaemia, mixed dyslipidaemia, statin intolerance, or when these are contraindicated. The marketing of bempedoic acid implies, in clinical practice, having a new family of lipid-lowering drugs., (Copyright © 2021 Sociedad Española de Arteriosclerosis. Publicado por Elsevier España, S.L.U. All rights reserved.)

We compared absolute bioavailability of the chemical substance of the anti-smallpox preparation NIOCH-14 and chemical compound ST-246 active against orthopoxviruses after oral administration to mice in doses of 10 and 50 μg/g and intravenous administration to mice in a dose of 2 μg/g body weight. The absolute bioavailability of NIOCH-14 is comparable with the absolute bioavailability of ST-246.

Background and Objective: Vidofludimus is a potent and selective inhibitor of human mitochondrial enzyme dihydroorotate dehydrogenase (DHODH). The clinical efficacy and safety profile of vidofludimus has been analyzed in patients suffering from rheumatoid arthritis and Crohn's disease and ulcerative colitis. In previous sudies, hematuria at higher doses occurred in close temporal relationship to vidofludimus administration and appeared to be dose related. The present report describes the results from two phase 1 studies conducted in healthy male subjects to investigate the safety, tolerability and pharmacokinetics after single and multiple ascending (SAD and MAD) oral doses of IMU-838 (vidofludimus calcium, tablets containing a specific polymorph). The effect of food on the pharmacokinetics of IMU-838 was also assessed in the SAD study., Methods: In the SAD study, 12 subjects received single doses of IMU-838 under fasting (10-40 mg) or fed (10 mg) condition in an open-label, partial parallel group design. In the MAD study, 52 subjects received multiple doses of IMU-838 (30-50 mg) in a double-blind, placebo-controlled, parallel group design., Results: IMU-838 showed dose-proportional pharmacokinetics after single and multiple oral dosing in both SAD and MAD studies. IMU-838 was well absorbed after single daily doses. Food did not impact the pharmacokinetics of IMU-838. The accumulation factor for multiple daily dosing was approximately 2. Steady-state concentrations were reached within about 6-8 days for 30-50 mg groups. The geometric mean plasma half-life of IMU-838 at steady state was approximately 30 h, which supports its use for once-daily dosing regimen. Single and multiple oral doses of IMU-838 were safe and well tolerated., Conclusion: Overall, oral IMU-838 was generally well tolerated in SAD and MAD studies in healthy subjects over a wide dose range of 10-50 mg. IMU-838 was well absorbed after single daily doses. IMU-838 showed dose proportional pharmacokinetics after single and multiple oral dosing.

For decades, phthalates have been widely used as plasticizers in a large number of consumer products, leading to a complex exposure to humans via ingestion, inhalation or dermal uptake. Children may have a higher unintended dust intake per day compared to adults. Therefore, dust intake of children could pose a relevant exposure and subsequently a potential health risk. The aim of this study was to determine the relative bioavailability of certain phthalates, such as di(2-ethylhexyl) phthalate (DEHP), di-isononyl phthalate (DINP) and the non-phthalate plasticizer diisononyl 1,2-cyclohexanedicarboxylic acid (DINCH ® , Hexamoll ® ), after ingestion of dust. Seven 5-week-old male piglets were fed five different dust samples collected from daycare centers. Overall, 0.43 g to 0.83 g of dust sieved to 63 μm were administered orally. The piglets' urine was collected over a period of 38 h. The excreted metabolites were quantified using an LC-MS/MS method. The mean uptake rates of the applied doses for DEHP, DINP, and DINCH ® were 43% ± 11%, 47% ± 26%, and 9% ± 3.5%, respectively. The metabolites of DEHP and DINP showed maximum concentrations in urine after three to five hours, whereas the metabolites of DINCH ® , reached maximum concentrations 24 h post-dose. The oral bioavailability of the investigated plasticizers was higher compared to the bioaccessibility reported from in vitro digestion tests. Furthermore, the bioavailability of DEHP did not vary substantially between the dust samples, whereas a dose-dependent saturation process for DINP was observed. In addition to other intake pathways, dust could be a source of plasticizers in children using the recent intake rates for dust ingestion., (Copyright © 2019 Elsevier B.V. All rights reserved.)

MGS0274 besylate is an ester-based lipophilic prodrug of a metabotropic glutamate (mGlu) 2 and mGlu3 receptor agonist MGS0008 and being developed for the treatment of schizophrenia. We investigated the disposition of these compounds in rats and monkeys and in vitro metabolism in humans to evaluate whether MGS0274 besylate could be useful as a prodrug in humans. After the oral administration of MGS0274 besylate to monkeys (2.89 mg/kg), MGS0008 was immediately found in plasma, reached a maximum concentration at 4 hours postdose, and decreased with a terminal half-life of 16.7 hours; MGS0274 was barely detectable. The oral bioavailability as MGS0008 was 83.7%, which was approximately 20-fold greater than that after oral dosing of MGS0008 (3.8%). In rats, MGS0008 penetrated the cerebrospinal fluid and was eliminated slower than from plasma. The in vitro metabolism study indicated that MGS0274 was rapidly hydrolyzed to MGS0008, which was not further metabolized. After the intravenous administration of MGS0008 to rats and monkeys, almost all the dose was excreted unchanged in urine. These results suggested that MGS0274 was, as expected, presystemically hydrolyzed to MGS0008 after gastrointestinal absorption and that MGS0008 was distributed throughout the body without further metabolism and ultimately excreted in urine in the animals. Furthermore, the hydrolytic activity against MGS0274 in the human liver S9 fraction was comparable to that in monkeys, suggesting the possibility of the rapid presystemic hydrolysis of MGS0274 to MGS0008 in humans, as it is in monkeys. Consequently, MGS0274 besylate is expected to function as a preferable prodrug in humans., Competing Interests: The authors declare that there is no conflict of interest.

Background: Bempedoic acid is an oral, once-daily, first-in-class medication being developed to treat hypercholesterolemia., Objective: The aim of the study was to assess the low-density lipoprotein cholesterol (LDL-C)-lowering efficacy of bempedoic acid added to stable high-intensity atorvastatin background therapy and multiple-dose plasma pharmacokinetics of atorvastatin alone and combined with steady-state bempedoic acid., Methods: This was a phase 2 study in patients with hypercholesterolemia (NCT02659397). Patients received once-daily open-label atorvastatin 80 mg for 4 weeks then were randomized 2:1 at baseline to receive double-blind bempedoic acid 180 mg (n = 45) or placebo (n = 23) plus open-label atorvastatin 80 mg for 4 weeks. Efficacy was assessed 4 weeks after randomization. Atorvastatin and metabolites' steady-state levels were analyzed before first dosing with bempedoic acid and after 2 weeks of treatment., Results: The 4-week stabilization phase with 80 mg atorvastatin resulted in approximately 40% lowering of LDL-C values from screening. The placebo-adjusted least squares mean lowering of LDL-C from baseline to Day 29 with bempedoic acid was 22% (P = .003). Placebo-adjusted reductions from baseline with bempedoic acid also were significant for total cholesterol (-10%; P = .014), non-high-density lipoprotein cholesterol (-13%; P = .015), apolipoprotein B (-15%; P = .004), and high-sensitivity C-reactive protein (-44%; P = .002). Point estimates of bempedoic acid effects on steady-state atorvastatin and ortho-hydroxy atorvastatin area under the curve were <30% and not clinically meaningful., Conclusions: Bempedoic acid 180 mg added to stable high-dose atorvastatin therapy effectively lowers LDL-C in patients with hypercholesterolemia without causing clinically important increases in atorvastatin exposure., (Copyright © 2019 National Lipid Association. Published by Elsevier Inc. All rights reserved.)

Molecular recognition has central role on the development of rational drug design. Binding affinity and interactions are two key components which aid to understand the molecular recognition in drug-receptor complex and crucial for structure-based drug design in medicinal chemistry. Herein, we report the binding affinity and the nonbonding interactions of azelaic acid and related compounds with the receptor DNA polymerase I (2KFN). Quantum mechanical calculation was employed to optimize the modified drugs using B3LYP/6-31G(d,p) level of theory. Charge distribution, dipole moment and thermodynamic properties such as electronic energy, enthalpy and free energy of these optimized drugs are also explored to evaluate how modifications impact the drug properties. Molecular docking calculation was performed to evaluate the binding affinity and nonbonding interactions between designed molecules and the receptor protein. We notice that all modified drugs are thermodynamically more stable and some of them are more chemically reactive than the unmodified drug. Promise in enhancing hydrogen bonds is found in case of fluorine-directed modifications as well as in the addition of trifluoroacetyl group. Fluorine participates in forming fluorine bonds and also stimulates alkyl, pi-alkyl interactions in some drugs. Designed drugs revealed increased binding affinity toward 2KFN. A1, A2 and A3 showed binding affinities of -8.7, -8.6 and -7.9 kcal/mol, respectively against 2KFN compared to the binding affinity -6.7 kcal/mol of the parent drug. Significant interactions observed between the drugs and Thr358 and Asp355 residues of 2KFN. Moreover, designed drugs demonstrated improved pharmacokinetic properties. This study disclosed that 9-octadecenoic acid and drugs containing trifluoroacetyl and trifluoromethyl groups are the best 2KFN inhibitors. Overall, these results can be useful for the design of new potential candidates against DNA polymerase I.

Hexamoll ® DINCH is an important alternative to phthalate plasticizers. Although regulatory reviews have not identified any potential hazards even in sensitive populations, an in vitro study by Campioli et al. (2015) suggested Hexamoll ® DINCH might alter fat storage in adipocytes resulting in obesity. To evaluate this hypothesis, data from studies with Hexamoll ® DINCH were reviewed for evidence of deposition in fat, changes in body weight, or changes in serum chemistry reflecting altered metabolic status. Body weights of F1 and F2 pups in a two-generation study did not differ from controls even at 1000 mg Hexamoll ® DINCH/kg body weight. Mean relative liver weights from the 1000 and 300 mg/kg bw groups were increased, but without histopathologic changes. Triglyceride and cholesterol levels in serum were not affected. In addition, subchronic and chronic studies in rats did not give evidence of an obesogenic effect. Radioactivity from 20 or 1000 mg/kg bw 14 C-labelled Hexamoll ® DINCH dosed orally remained 2-3 times longer in adipose tissue than in well-perfused tissues; however, levels were 20-500% below other tissues at 1 and 8 h post dosing. Radioactivity concentrations in organs and tissues excluding the GI tract declined rapidly and continuously, and decreased in parallel to the concentration in plasma during the following 20 h. Both, initial and terminal half-lives of radioactivity concentration do not indicate a potential for accumulation. Furthermore, a metabolomic comparison of Hexamoll ® DINCH with DEHP and other phthalates shows complete separation of the metabolomic profile of these two chemical classes, meaning that their effects on the body and the body's reaction to the substance are different. Hence, comprehensive in vivo data do not show any evidence of Hexamoll ® DINCH altering fat metabolism or having obesogenic properties., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Objective: Bempedoic acid (BemA; ETC-1002) is a novel drug that targets hepatic ATP-citrate lyase to reduce cholesterol biosynthesis. In phase 2 studies, BemA lowers elevated low-density lipoprotein cholesterol (LDL-C) in hypercholesterolemic patients. In the present study, we tested the ability of BemA to decrease plasma cholesterol and LDL-C and attenuate atherosclerosis in a large animal model of familial hypercholesterolemia., Approach and Results: Gene targeting has been used to generate Yucatan miniature pigs heterozygous ( LDLR +/- ) or homozygous ( LDLR -/- ) for LDL receptor deficiency (ExeGen). LDLR +/- and LDLR -/- pigs were fed a high-fat, cholesterol-containing diet (34% kcal fat; 0.2% cholesterol) and orally administered placebo or BemA for 160 days. In LDLR +/- pigs, compared with placebo, BemA decreased plasma cholesterol and LDL-C up to 40% and 61%, respectively. In LDLR -/- pigs, in which plasma cholesterol and LDL-C were 5-fold higher than in LDLR +/- pigs, BemA decreased plasma cholesterol and LDL-C up to 27% and 29%, respectively. Plasma levels of triglycerides and high-density lipoprotein cholesterol, fasting glucose and insulin, and liver lipids were unaffected by treatment in either genotype. In the aorta of LDLR +/- pigs, BemA robustly attenuated en face raised lesion area (-58%) and left anterior descending coronary artery cross-sectional lesion area (-40%). In LDLR -/- pigs, in which lesions were substantially more advanced, BemA decreased aortic lesion area (-47%) and left anterior descending coronary artery lesion area (-48%)., Conclusions: In a large animal model of LDLR deficiency and atherosclerosis, long-term treatment with BemA reduces LDL-C and attenuates the development of aortic and coronary atherosclerosis in both LDLR +/- and LDLR -/- miniature pigs., (© 2018 American Heart Association, Inc.)

Although statins are first-line therapy for low-density lipoprotein cholesterol (LDL-C) reduction, many individuals on maximally tolerated statin therapy have elevated LDL-C. Bempedoic acid (ETC-1002) is a novel once-daily LDL-C-lowering agent in phase 3 clinical trials. In phase 1 and 2 studies, ETC-1002 was efficacious in lowering LDL-C when used as monotherapy and when added to statin and/or ezetimibe and was well tolerated in patients with statin intolerance. ETC-1002 also improved cardiometabolic risk factors. Ongoing phase 3 studies of ETC-1002 are evaluating its long-term efficacy and safety, and effects on cardiovascular events. This article discusses current evidence and future directions for ETC-1002., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Azelaic acid is a dicarboxylic acid compound used in treatment of acne vulgaris. However, high concentration (ca 20%) is needed to guarantee the drug availability in the skin. The latter increases the incidence of side effects such as local irritation. The prodrug strategy to enhance azelaic acid diffusion through skin was not reported before. Thus, a lipophilic prodrug of azelaic acid (diethyl azelate [DEA]) was synthesized and investigated to improve percutaneous availability of azelaic acid, with a subsequent full physical, chemical, and biological characterization. Expectedly, DEA exhibited a significant increase in diffusion compared to azelaic acid through silicone membrane. In contrast, the diffusion results through human stratum corneum (SC) displayed weaker permeation for DEA with expected retention in the SC. Therefore, a desorption study of DEA from SC was conducted to examine the reservoir behavior in SC. Results showed an evidence of sustained release behavior of DEA from SC. Consequently, enhancement of keratolytic effect is expected due to azelaic acid produced from enzymatic conversion of DEA released from SC.

Purpose: To prepare the supramolecular cocrystals of gliclazide (GL, a BCS class II drug molecule) via mechanochemical route, with the goal of improving physicochemical and biopharmaceutical properties., Methods: Two cocrystals of GL with GRAS status coformers, sebacic acid (GL-SB; 1:1) and α-hydroxyacetic acid (GL-HA; 1:1) were screened out using liquid assisted grinding. The prepared cocrystals were characterized using thermal and analytical techniques followed by evaluation of antidiabetic activity and pharmacokinetic parameters., Results: The generation of new, single and pure crystal forms was characterized by DSC and PXRD. The crystal structure determination from PXRD revealed the existence of both cocrystals in triclinic (P-1) crystal system. The hydrogen bonded network, determined by material studio was well supported by shifts in FTIR and SSNMR. Both the new solid forms displayed improved solubility, IDR, antidiabetic activity and pharmacokinetic parameters as compared to GL., Conclusions: The improvement in these physicochemical and biopharmaceutical properties corroborated the fact that the supramolecular cocrystallization may be useful in the development of pharmaceutical crystalline materials with interesting network and properties.

Di(isononyl)cyclohexane-1,2-dicarboxylate (DINCH), a non-phthalate plasticizer, was introduced commercially in 2002 as an alternative to ortho-phthalate esters because of its favorable toxicological profile. However, the potential health effects from DINCH exposure remain largely unknown. We explored the associations between urinary concentrations of metabolites of DINCH on markers of ovarian response among women undergoing in vitro fertilization (IVF) treatments. Between 2011 and 2015, 113 women enrolled a prospective cohort study at the Massachusetts General Hospital Fertility Center and provided up to two urine samples prior to oocyte retrieval. The urinary concentrations of two DINCH metabolites, cyclohexane-1,2-dicarboxylic acid monohydroxy isononyl ester (MHiNCH) and cyclohexane-1,2-dicarboxylic acid monocarboxyisooctyl ester (MCOCH), were quantified by isotope dilution tandem mass spectrometry. We used generalized linear mixed models to evaluate the association between urinary metabolite concentrations and markers of ovarian response, accounting for multiple IVF cycles per woman via random intercepts. On average, women with detectable urinary MHiNCH concentrations, as compared to those below LOD, had a lower estradiol levels (-325 pmol/l, p=0.09) and number of retrieved oocytes (-1.8, p=0.08), with a stronger association among older women. However, urinary MHiNCH concentrations were unrelated to mature oocyte yield and endometrial wall thickness. In conclusion, we found suggestive negative associations between urinary MHiNCH concentrations and peak estradiol levels and number of total oocyte yields. This is the first study evaluating the effect of DINCH exposure on human reproductive health and raises the need for further experimental and epidemiological studies to better understand the potential effects of this chemical on health., Competing Interests: None of the authors has any conflicts of interest to declare. The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention (CDC). Use of trade names is for identification only and does not imply endorsement by the CDC, the Public Health Service, or the US Department of Health and Human Services., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Polyanhydride nanoparticles have emerged as a versatile delivery platform, due to their ability to encapsulate diverse drugs, immunogens, antibodies, and proteins. However, mechanistic studies on the effects of particle chemistry interactions with immune cells have yet to be described. Understanding the mechanism by which these particles are internalized by immune cells will enable rational selection of delivery vehicles for specific applications. In the present study, the internalization, mechanism(s) of uptake by monocytes, and intracellular fate of polyanhydride nanoparticles were evaluated using copolymers based on 1,6-bis(p-carboxyphenoxy)hexane (CPH), sebacic acid (SA), and 1,8-bis(p-carboxyphenoxy)3,6-dioxaoctane (CPTEG). The results showed that 20:80 CPH:SA and 20:80 CPTEG:CPH nanoparticles were internalized to a greater extent by monocytes as compared to the 50:50 CPH:SA and 50:50 CPTEH:CPH nanoparticles. Further, cytochalasin-D treatment of cells inhibited uptake of all the particles, regardless of chemistry, indicating that actinmediated uptake is the primary mechanism of cellular entry for these particles. The insights gained from these studies were used to identify lead nanoparticle formulations to enhance treatment of intracellular bacterial infections. The use of doxycycline-loaded nanoparticles exhibited enhanced therapeutic efficacy compared to soluble drug in treating monocyte monolayers infected with the virulent intracellular pathogen Brucella abortus. Altogether, these studies demonstrate how rational design and selection of nanoscale delivery platforms can be used for a wide spectrum of biomedical applications.

Alternative plasticizers to di(2-ethylhexyl) phthalate (DEHP) for blood bags have been sought for many years. Cyclohexane-1,2-dicarboxylic acid, diisononylester (Hexamoll(®) DINCH(®)) is an alternative that has been evaluated in preliminary studies for compatibility and efficacy to preserve whole blood. While Hexamoll(®) DINCH(®) has an extensive database for mammalian toxicity via oral administration, data were needed to evaluate toxicity from intravenous (IV) administration to support the use of the plasticizer Hexamoll(®) DINCH(®) in blood bags. A series of studies was performed by slow IV injection or IV infusion of Hexamoll(®) DINCH(®), a highly viscous, hydrophobic substance, suspended in Intralipid(®) 20% (20% intravenous fat emulsion). Rats were injected once, followed by 14 days of recovery; injected daily for 5 days followed by 5 days of recovery, or infused for 29 days (4h/day) followed by 14 days of recovery. Dose levels were 0, 62, 125, and 250-300mg/kg body weight/day. These dose levels represent the limits of suspension and far exceed any anticipated exposures from migration out of plasticized blood bags. Animals were observed for signs of toxicity; body weight and feed consumption were measured; blood collected for clinical chemistry and hematology; and tissues collected and processed for histopathology. Special emphasis was placed on evaluating endpoints and tissues that are commonly associated with plasticizer exposure in rodents. Urine was collected during the 4-week study to quantify urinary metabolites of Hexamoll(®) DINCH(®). The results of the studies indicate that no substance-related toxicity occurred: no effects on behavior, no effects on organ weight, no effect on serum chemistry including thyroid hormones; and no effect on major organs, especially no testicular toxicity and no indication for peroxisome proliferation in the liver. The only effects seen were petechia and granulomas related to dissipation of suspended Hexamoll(®) DINCH(®) in the aqueous environment of the blood. However, the results of metabolite analyses demonstrate that Hexamoll(®) DINCH(®) was bioavailable. Therefore, based on the lack of Hexamoll(®) DINCH(®)-related systemic toxicity with the exception of the physical limitations, the no-observed-adverse-effect level for parenterally administered Hexamoll(®) DINCH(®) is considered to be 300mg/kg bw/day., (Copyright © 2015 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.)

We developed and calibrated a multi compartment pharmacokinetic (PK) model to predict urinary concentrations after oral exposure of four specific DINCH metabolites: MINCH, OH-MINCH, cx-MINCH, and oxo-MINCH. This descriptive model has 4 compartments: a "stomach" (SC) compartment, a "holding" (HC) compartment, a "blood" (BC) compartment and a "bladder" (BLC) compartment. DINCH is assumed to first deposit into the SC, with transfer split between the HC and the BC. Unmetabolized DINCH from the HC then transfers to the BC. The DINCH metabolism is assumed to occur in the BC before excretion via the BLC. At each urination event, all the metabolite mass in the BLC is excreted. The model was calibrated using published urine metabolite data from 3 different male volunteers, each orally dosed with 50mg DINCH. Full urine voids were taken for 48 h after dosage. The predicted values showed a good agreement with the observed urinary DINCH metabolite concentrations, with a Spearman correlation coefficient exceeding 0.7 for all oxidized metabolites. We showed the importance of a holding reservoir. Without it, a good agreement could not be found. We applied the model to a set of 24-h general population samples measured for DINCH metabolites. The model was unable to duplicate the ratio of metabolites seen in the 24-h samples. Two possibilities were offered to explain the difference: the exposure pattern in the general population did not match the oral exposure in the dosing experiments, or the long-term toxicokinetics of DINCH was not captured in the 48-h controlled dosing experiments., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

1,2-Cyclohexanedicarboxylic acid, 1,2-diisononylester (DINCH), a polyvinyl chloride plasticizer, has food, beverage, and medical device applications that may result in general population exposure. Although no apparent toxicity information in humans was identified, there is a substantial data set in lab animals to serve as the basis of hazard identification for DINCH. Target tissues associated with repeated dietary DINCH exposure in lab animals included liver, kidney, and thyroid and mammary glands. In contrast to some phthalate ester plasticizers, DINCH did not show evidence of hepatic peroxisomal proliferation, testicular toxicity, or liver tumors in rats. Liver and thyroid effects associated with DINCH exposure were attributed to compensatory thyroid stimulation secondary to prolonged metabolic enzyme induction. The toxicological significance of mammary fibroadenomas in female rats is unclear, given that this common benign and spontaneously occurring tumor type is unique to rats. The weight of evidence suggests DINCH is not genotoxic and the proposed mode of action (MOA) for thyroid gland lesions was considered to have a threshold. No adverse reproductive effects were seen in a two-generation study. An oral reference dose (RfD) of 0.7 mg/kg-d was derived from a human equivalent BMDL₁₀ of 21 mg/kg-d for thyroid hypertrophy/hyperplasia seen in adult F₁ rats also exposed in utero. The total uncertainty factor of 30x was comprised of intraspecies (10×) and database (3×) factors. An interspecies extrapolation factor was not applied since rodents are more sensitive than humans with respect to the proposed indirect MOA for thyroid gland lesions.

Sildenafil is a drug used to treat erectile dysfunction and pulmonary arterial hypertension. Because of poor aqueous solubility of the drug, the citrate salt, with improved solubility and pharmacokinetics, has been marketed. However, the citrate salt requires an hour to reach its peak plasma concentration. Thus, to improve solubility and bioavailability characteristics, cocrystals and salts of the drug have been prepared by treating aliphatic dicarboxylic acids with sildenafil; the N-methylated piperazine of the drug molecule interacts with the carboxyl group of the acid to form a heterosynthon. Salts are formed with oxalic and fumaric acid; salt monoanions are formed with succinic and glutaric acid. Sildenafil forms cocrystals with longer chain dicarboxylic acids such as adipic, pimelic, suberic, and sebacic acids. Auxiliary stabilization via C-H···O interactions is also present in these cocrystals and salts. Solubility experiments of sildenafil cocrystal/salts were carried out in 0.1N HCl aqueous medium and compared with the solubility of the citrate salt. The glutarate salt and pimelic acid cocrystal dissolve faster than the citrate salt in a two hour dissolution experiment. The glutarate salt exhibits improved solubility (3.2-fold) compared to the citrate salt in water. Solubilities of the binary salts follow an inverse correlation with their melting points, while the solubilities of the cocrystals follow solubilities of the coformer. Pharmacokinetic studies on rats showed that the glutarate salt exhibits doubled plasma AUC values in a single dose within an hour compared to the citrate salt. The high solubility of glutaric acid, in part originating from the strained conformation of the molecule and its high permeability, may be the reason for higher plasma levels of the drug.

Hexamoll(®) DINCH(®) (diisononyl-cyclohexane-1,2-dicarboxylate) is a new high-molecular-weight plasticizer and a phthalate substitute. In this study, the metabolism of DINCH(®) was investigated by oral dosage of three male volunteers with approximately 50 mg Hexamoll(®) DINCH(®) (resulting in individual doses between 0.552 and 0.606 mg/kg body weight). Their urine samples were consecutively collected over 48 h. In analogy to di-iso-nonylphthalate (DINP) metabolism, we quantified the simple monoester mono-isononyl-cyclohexane-1,2-dicarboxylate (MINCH) and its secondary oxidized metabolites with HPLC-MS/MS via isotope dilution analysis. Additionally, we quantified the unspecific full breakdown product, cyclohexane-1,2-dicarboxylic acid (CHDA), via standard addition. All postulated metabolites were present in all samples analyzed. The unspecific CHDA was identified as the major urinary metabolite representing 23.7 % of the dose as the mean of the three volunteers (range 20.0-26.5 %). 14.8 % (11.3-16.7 %) of the dose was excreted as monoesters with oxidative modifications, in particular OH-MINCH 10.7 % (7.7-12.9 %), oxo-MINCH 2.0 % (1.5-2.6 %) and carboxy-MINCH 2.0 % (1.8-2.3 %). Less than 1 % was excreted as the simple monoester MINCH. In sum, 39.2 % (35.9-42.4 %) of the DINCH(®) dose was excreted as these metabolites in urine within 48 h. Over 90 % of the metabolites investigated were excreted within 24 h after application. The secondary oxidized metabolites, with elimination half-times between 10 and 18 h, proved to be apt and specific biomarkers to determine DINCH(®) exposure. With this study, we provide reliable urinary excretion factors to calculate DINCH(®) intakes based on these metabolites in environmental and occupational studies.

Unlabelled: TRANSLATIONAL RELEVANCE: Dicycloplatin (DCP) is a novel super molecule composed of carboplatin (CBP) and 1,1-cyclobutane dicarboxylate (CBDCA) joined by a strong hydrogen bond. The solubility and stability of platinum complexes have a direct bearing on their activity, toxicity and pharmacokinetics. Preclinical studies have shown that DCP overcomes the problem of CBP instability in aqueous solution and maintains anticancer effects. Clinical evaluation in a Phase I dose-escalation study in patients with tumors showed that DCP was tolerated at doses ranging from 100 to 550 mg/m(2) and had potential efficacy in Chinese cancer patients. DCP showed favourable bioavailability and stability in vivo, and the recommended Phase II dosage for DCP-containing chemotherapy is 450 mg/m(2). DCP is currently being investigated as a monotherapy in several cancer types, such as prostatic carcinoma, and in combination with paclitaxel in a Phase II non-lung cancer study., Purpose: Dicycloplatin (DCP) is a novel supramolecule composed of carboplatin (CBP) and 1,1-cyclobutane dicarboxylate (CBDCA) joined by a strong hydrogen bond. DCP is stable in aqueous solution unlike CBP alone. The purpose of this study was to assess the maximally tolerated dose, safety, and pharmacokinetics of DCP in Chinese cancer patients., Experimental Design: 29 patients were included in this study. DCP was administered by intravenous infusion over 1 hour once every 21 days. The dose of DCP was escalated from 50 mg/m(2) to 650 mg/m(2) using a modified Fibonacci scheme. Pharmacokinetic analysis was performed in 26 patients to determine the total and ultrafiltered platinum concentrations in plasma., Results: 29 and 20 patients were evaluated for toxicities and response, respectively. The primary adverse effects were nausea/vomiting (58.6%), thrombocytopenia (24.1%), neutropenia (17.2%), anemia (20.7%), fatigue (10.3%), anorexia (10.3%), liver enzyme elevation (10.3%) and alopecia (3.5%). There was no significant toxicity with doses up to 350 mg/m(2). At higher doses, a variety of dose-limiting toxicities (DLTs) were observed, including Grade 3/4 anemia, Grade 3/4 thrombocytopenia, and Grade 3/4 emesis under antiemetic treatment. The maximum tolerated dose of DCP was 550 mg/m(2). Two partial responses occurred in patients with non-cell lung cancer who had received cisplatin- or carboplatin-based chemotherapy. Plasma decay of total and free platinum concentrations was best fitted by using a twocompartment analysis. The terminal plasma half-life of total platinum after DCP administration ranged from 41.86 to 77.20 hours without significant dose dependency. However, the terminal plasma half-life of free platinum concentrations ranged from 42.34 to 61.07 hours., Conclusions: DCP displayed a favorable safety profile at doses between 50 mg/m(2) and 550 mg/m(2), and first efficacy signals were observed. DLTs were thrombocytopenia, anemia and emesis. The recommended starting dose for a subsequent Phase II study is 450 mg/m(2) once every 3 weeks.

Objective: The aim of this study is to investigate the effect of ionization and vehicle of topical formulations on skin absorption and penetration of azelaic acid (AZA)., Materials and Methods: In vitro transport of AZA was determined for two topical formulations containing AZA with pH values of 3.9 and 4.9, respectively. FINACEA(®) (15% AZA gel), a US Food and Drug Administration approved drug for treatment of acne and rosacea, was also used for comparison. Release profile and flux of AZA were determined in an in vitro hairless mouse skin model using Franz Diffusion Cell., Results: The data have shown that a higher concentration of AZA is retained in the epidermis/dermis layer and the whole skin for the formulation with pH = 4.9 as compared to that with pH = 3.9 at an active loading level of 2.82 mg/cm(2). In addition, the flux of ionized species of AZA in the pH 4.9 formulation (128.4 ± 35.9 μg/cm(2)/h) is approximately five-fold greater than that in the pH 3.9 formulation (27.7 ± 4.0 μg/cm(2)/h). The results suggest that the ionized AZA penetrates through the skin and accounts for majority of the total flux., Discussion and Conclusion: This study has demonstrated that the penetration and absorption of AZA show a strong pH- and vehicle-dependency. Solubilization is the rate-limiting step in percutaneous absorption of AZA.

The CIR Expert Panel assessed the safety of dicarboxylic acids and their salts and esters as used in cosmetics. Most dicarboxylic acids function in cosmetics as pH adjusters or fragrance ingredients, but the functions of most of the salts in cosmetics are not reported. Some of the esters function as skin conditioning or fragrance ingredients, plasticizers, solvents, or emollients. The Expert Panel noted gaps in the available safety data for some of the dicarboxylic acid and their salts and esters in this safety assessment. The available data on many of the ingredients are sufficient, however, and similar structural activity relationships, biologic functions, and cosmetic product usage suggest that the available data may be extrapolated to support the safety of the entire group. The Panel concluded that the ingredients named in this report are safe in the present practices of use and concentration.

A co-drug of hydroquinone (HQ) and azelaic acid (AA), bis(4-hydroxyphenyl)nonanedioate (BHN), was synthesized and investigated as a topical prodrug with the aim of improving the dermal delivery of the parent drugs. Physicochemical parameters were ascertained, and the enzymatic hydrolysis was examined. Skin permeation of HQ, AA, and BHN was studied by determining the skin deposition and flux across nude mouse skin under equivalent doses with the same thermodynamic activity. The partition coefficient (log P) of the co-drug increased by up to 5.0 with HQ and AA conjugation, which had respective log P values of 0.5 and 1.4. In the skin absorption experiment, BHN in ethanol/pH 7 buffer resulted in a 2-fold enhancement of skin deposition compared to both HQ and AA. With permeation using polyethylene glycol 400/pH 7 buffer as the vehicle, the co-drug, respectively, exhibited 8.1- and 1.4-fold enhancements of skin uptake compared to HQ and AA alone. The transdermal flux from BHN was negligible compared to those with HQ and AA treatments. The results of a preliminary safety evaluation showed no signs of stratum corneum disruption or erythema by BHN application within 24h. The co-drug approach provides a viable option for the treatment of skin hyperpigmentation of HQ and AA., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The objective of this study is to investigate the effect of 1,4-cyclohexanediol as a retardant on the percutaneous absorption and penetration of azelaic acid. Hairless rat skin was mounted on Franz diffusion cells and treated with topical formulations containing solubilized azelaic acid with and without 1,4-cyclohexanediol. The skin was separated into stratum corneum and the deeper skin layers. The azelaic acid collected in receptor medium and each layer at the end of each time point was extracted and quantified. A significant decrease in flux across the skin suggests a penetration retardation effect of 1,4-cyclohexanediol (42.50 microg/cm(2)/h in the presence of vs. 76.25 microg/cm(2)/h in the absence of) at active loading level of 1.13 mg/cm(2). The penetration retardation effect was also observed at higher active loading level (2.82 mg/cm(2)). Furthermore, presence of 1,4-cyclohexanediol in the topical formulation did not reduce the skin and epidermal retention of azelaic acid, suggesting its potential use in the development of superior topical formation for reducing potential systematic side effect while maintaining therapeutic efficiency., (2009 Elsevier B.V. All rights reserved.)

It has been reported that both liquiritigenin (LQ) and dimethyl-4,4'-dimethoxy-5,6,5',6'-dimethylenedioxybiphenyl-2,2'-dicarboxylate (DDB) have a hepatoprotective effect, and administration of both drugs together shows additive protective effect against acute liver injuries. Therefore, the pharmacokinetic interaction between LQ and DDB in rats was studied. LQ (20 and 50mg/kg for the i.v. and p.o. administration, respectively), DDB (10mg/kg for both i.v. and p.o. administration), and both drugs together were once administered intravenously or orally to rats. After the i.v. administration of both drugs together, the Cl(nr) and AUC of LQ were significantly faster (by 30.5%) and smaller (by 22.5%), respectively, than those of without DDB due to the faster hepatic blood flow rate by DDB. After the p.o. administration of both drugs together, the AUC of LQ was comparable to that of without DDB due to negligible effect of DDB on intestinal metabolism of LQ. The pharmacokinetic parameters of DDB after both i.v. and p.o. administration were not altered by LQ, indicating that LQ did not considerably affect the pharmacokinetics of DDB in rats., (Copyright 2009 Elsevier B.V. All rights reserved.)

This study investigated the effect of emulsifiers and their liquid crystalline structures on the dermal and transdermal delivery of hydroquinone (HQ), salicylic acid (SA) and octadecenedioic acid (DIOIC). Emulsions containing liquid crystalline phases were compared with an emulsion without liquid crystals. Skin permeation experiments were performed using Franz-type diffusion cells and human abdominal skin dermatomed to a thickness of 400 mum. The results indicate that emulsifiers arranging in liquid crystalline structures in the water phase of the emulsion enhanced the skin penetration of the active ingredients with the exception of SA. SA showed a different pattern of percutaneous absorption, and no difference in dermal and transdermal delivery was observed between the emulsions with and without liquid crystalline phases. The increase in skin penetration of HQ and DIOIC could be attributed to an increased partitioning of the actives into the skin. It was hypothesized that the interaction between the different emulsifiers and active ingredients in the formulations varied and, therefore, the solubilization capacities of the various emulsifiers and their association structures., (Copyright 2010 S. Karger AG, Basel.)

Objectives: The objective of this study was to investigate the mechanism responsible for the poor oral bioavailability of dimethyl-4',4'-dimethoxy-5,6,5',6'-dimethylene dioxybiphenyl-2,2'-dicarboxylate (DDB), a hepatoprotective agent, in rats., Methods: DDB was intravenously administered to rats at doses of 0.2-1 mg/kg. To determine the hepatic first-pass effect in rats, DDB (1 mg/kg) was administered via the pyloric vein and the femoral vein. Direct measurement of intestinal permeability was attempted using Caco-2 cell monolayers and rat intestinal epithelium., Key Findings: A moment analysis indicated that the volume of distribution and clearance remained unchanged with the magnitude of the dose, indicating that DDB exhibited linear pharmacokinetics. When the area under the curve for DDB after administration to the pyloric vein was compared with that after femoral vein administration, the ratio (F(H)) was found to be 0.294, indicating a significant first-pass effect for DDB. The permeability of DDB was high in the rat intestine (1.78 +/- 0.229 x 10(-5) cm/s) and in Caco-2 cell monolayers (6.8 +/- 0.70 x 10(-5) cm/s), suggesting that DDB, in soluble form, was readily permeable across the intestinal epithelium., Conclusions: These observations indicated that despite the fact that DDB was readily permeable to the intestinal epithelium, a significant first-pass metabolism was associated with its pharmacokinetics in rats.

The medical management of rosacea increasingly has involved not only the appropriate selection of topical medication but also patient education and specific recommendations regarding appropriate skin care. The recognition that epidermal barrier dysfunction and transepidermal water loss (TEWL) play a pathophysiologic role in rosacea and that skin moisturization may help to mitigate signs and symptoms of the disease has led to a deeper appreciation of the importance of proper skin care in the treatment of rosacea. Data from a percutaneous penetration study performed using human skin suggest that any of the tested moisturizer lotions may be applied either before or after azelaic acid gel 15% without a major change in the percutaneous absorption profile of azelaic acid.

Rosacea represents a chronic inflammatory dermatosis of uncertain pathophysiology. There are several associated risk factors and the need for long-term treatment is well recognized. This diverse disease is frequently difficult to manage and has a significant impact on quality of life. There are several topical and oral treatments available, of which azelaic acid 15% gel (Finacea) is the first new treatment for rosacea in more than a decade. Azelaic acid per se has multiple modes of action in rosacea, but an anti-inflammatory effect achieved by reducing reactive oxygen species appears to be the main pharmacological action. Clinical studies have shown that azelaic acid 15% gel is an effective and safe first-line topical therapeutic option in patients with mild-to-moderate papulopustular rosacea. Significant continuous improvement in the number of inflammatory lesions and in erythema has been shown over a period of 15 weeks. Adverse effects associated with azelaic acid 15% gel are mostly mild or transient and do not usually necessitate discontinuation of therapy.

In this study the effect of 2 penetration modifiers, dimethyl isosorbide (DMI) and diethylene glycol monoethyl ether (DGME) on the skin delivery of hydroquinone (HQ), salicylic acid (SA) and octadecenedioic acid (DIOIC) was investigated. Ten percent DMI and DGME were separately formulated into oil-in-water emulsions containing 1.8% HQ, SA and DIOIC, respectively. Skin delivery and the flux across split-thickness human skin of the active ingredients were determined using Franz diffusion cells. An emulsion with 10% water incorporated instead of the water-soluble penetration modifiers served as a control. The study showed that neither 10% DMI nor 10% DGME significantly enhanced the skin permeation of the various lipophilic active ingredients or the uptake into the skin. It was hypothesized that the addition of the penetration modifiers to the emulsions not only enhanced the solubility of the various active ingredients in the skin but also in the formulation, resulting in a reduced thermodynamic activity and hence a weaker driving force for penetration. Therefore, the effect of DMI and DGME on the solubility of the active ingredients in the skin was counteracted by a simultaneous reduction in the thermodynamic activity in the formulation., (Copyright 2008 S. Karger AG, Basel.)

The drug release profiles of poly(dimer acid-dodecanedioic acid) P(DA-DDDA) copolymer containing 5% adriamycin hydrochloride (ADM) in vitro were evaluated. The biocompatibility of P(DA-DDDA) under mice skin was also evaluated, macroscopic observation and microscopic analysis demonstrated that the copolymer is biocompatible and well tolerated in vivo. Antitumor efficacy of P(DA-DDDA) copolymers containing 5% adriamycin hydrochloride (ADM) implanted subcutaneously in mice bearing Sarcoma-180 tumor exhibited increased volume doubling time (VDT) (31 +/- 1.5 days) compared to plain subcutaneous injection of ADM (7 +/- 0.9 days). The studies suggest that P(DA-DDDA) copolymer as an effective carrier for antineoplastic drug like adriamycin hydrochloride has a very good prospect in the treatment of noumenon tumors.

MGS0039 (3-(3,4-dichlorobenzyloxy)-2-amino-6-fluorobicyclo-[3.1.0]hexane-2,6-dicarboxylic acid) has been identified as a potent and selective antagonist for metabotropic glutamate receptors. However, the oral bioavailability of MGS0039 is 10.9% in rats, due to low absorption. Several prodrugs, synthesized to improve absorption, exhibited 40 to 70% bioavailability in rats. This study investigated in vitro metabolism using liver S9 fractions from both cynomolgus monkeys and humans and oral bioavailability in cynomolgus monkeys to select the prodrug most likely to exhibit optimal pharmacokinetic profiles in humans. In monkeys, transformation to active substance was observed (5.9-72.8%) in liver S9 fractions, and n-butyl, n-pentyl, 3-methylbutyl, and 4-methylpentyl ester prodrugs exhibited high transformation ratios (>64%). Cmax levels and F values after oral dosing increased to 4.1- to 6.3-fold and 2.4- to 6.3-fold, respectively, and a close relationship between transformation ratios and Cmax and F values was observed, indicating that the hydrolysis rate in liver S9 fractions is the key factor in determining oral bioavailability in monkeys. In humans, n-hexyl, n-heptyl, n-octyl, 5-methylbutyl, and 6-methylpentyl ester prodrugs exhibited high transformation ratios (>65%) in liver S9 fractions. With these prodrugs, n-hexyl, n-heptyl, and 5-methylpentyl ester, almost complete recovery (96-99%) was obtained. Given the transformation ratio, we anticipated that the n-heptyl alkyl ester prodrug would exhibit the highest oral bioavailability of active substances in humans, if the hydrolysis rate in liver S9 fractions is indeed the key factor in determining oral bioavailability in humans. On this basis, MGS0210 (3-(3,4-dichlorobenzyloxy)-2-amino-6-fluorobicyclo[3.1.0]hexane-2,6-dicarboxylic acid n-heptyl ester) seems to be a promising candidate among MGS0039 prodrugs.

Dicarboxylic acids with an even number of carbon atoms have been proposed as an alternate energy substrate for enteral or parenteral nutrition in the acutely ill patient, due to their water solubility and their yielding TCA cycle intermediates upon beta-oxidation. In the present work, a nonlinear compartmental model of the kinetics of dodecanedioic acid is developed, and its parameters are estimated from time concentration experimental observations obtained from six healthy volunteers undergoing a per os administration of 3 g of the substance. Although the model is linear in the transfer of the free substance from plasma to the tissues, the exchange between gut and plasma compartments is represented as a saturable function. Albumin binding is then incorporated to obtain the final model in terms of the measured total concentrations. Estimates of the model's structural parameters were computed for each experimental subject, and the usual single-subject approximate confidence regions for the parameters were derived by inversion of the Hessian at the optimum. To verify the applicability of this approximation, the nonlinearity of the expectation surface at the optimum was measured by computing the normal (intrinsic) component of curvature. Because the model curvature was excessive in all subjects, the usual approximation could not be trusted to provide acceptable approximations to the parameter confidence regions. A suitable Monte Carlo simulation yielded empirical joint parameter distributions from which the approximate parameter variances could finally be obtained.

Metabolism and disposition of MGS0028 [(1R,2S,5S,6S)-2-amino-6-fluoro-4-oxobicyclo[3.1.0]hexane-2,6-dicarboxylic acid monohydrate], a potent group II metabotropic glutamate receptor agonist, were examined in three preclinical species (Sprague-Dawley rats, beagle dogs, and rhesus monkeys). In rats, MGS0028 was widely distributed and primarily excreted in urine as parent and as a single reductive metabolite, identified as the 4R-isomer MGS0034 [(1R,2S,4R,5S,6S)-2-amino-6-fluoro-4-hydroxybicyclo[3.1.0]-hexane-2,6-dicarboxylic acid]. MGS0028 had a low brain to plasma ratio at efficacious doses in rats and was eliminated more slowly in rat brain than in plasma. Exposure increased proportionally (1--10 mg/kg p.o.) in rats, with bioavailability>60% at all doses. However, bioavailability was only approximately 20% in monkeys, and MGS0034 was found in relatively high abundance in plasma. In dogs, oral bioavailability was >60%, and the metabolite was not detected. In vitro metabolism was examined in liver subcellular fractions (microsomes and cytosol) from rat, dog, monkey, and human. Reductive metabolism was observed in rat, monkey, and human liver cytosol incubations, but not in dog liver cytosol incubations. No metabolism of MGS0028 was detected in incubations with liver microsomes from any species. Similar to in vivo results, MGS0028 was reduced in cytosol stereospecifically to MGS0034. The rank order of in vitro metabolite formation (monkey >> rat approximately human >> dog) was in agreement with in vivo observations in rats, dogs, and monkeys. Based on the observation of species difference in reductive metabolism, rat and monkey were recommended to be the preclinical species for further characterization prior to testing in humans. Finally, allometric scaling predicts that human pharmacokinetic parameters would be acceptable for further development.

Deterministic and stochastic differential equations models of the uptake of dodecanedioic acid (C12) are fitted to experimental data obtained on nine isolated, perfused rat livers. 11500 mug of C12 were injected as a bolus into the perfusing liver solution. The concentrations of C12 in perfusate samples taken over 2 h from the beginning of the experiments were analyzed by High Performance Liquid Chromatography (HPLC). A two-compartment deterministic model is studied. To include spontaneous erratic variations in the metabolic processes the parameter for the uptake rate is randomized to obtain a stochastic differential equations model. Parameters are estimated in a two-step procedure: first, parameters in the drift part are estimated by least squares; then, the diffusion parameter is estimated using Monte-Carlo simulations to approximate the unknown likelihood function. Parameter estimation is carried out over a wide range of reasonable measurement error variances to check robustness of estimates. It is concluded that the kinetics of dodecanedioic acid, in the experimental conditions discussed, is well approximated by a model including spontaneous erratic variations in the liver uptake rate.

The aim of this study was to investigate the release rates of azelaic acid and azelaic acid-hydroxypropyl-beta-cyclodextrin (HPbetaCD) inclusion complex through three types of synthetic membranes, namely cellophane, silicone and elastomer membranes. Solid inclusion complexes of azelaic acid-HPbetaCD at the molar ratio of 1:1 were prepared by coevaporation and freeze-drying methods, subsequently characterized by differential scanning calorimetry, X-ray diffractometry and dissolution studies. Solid inclusion complex obtained by coevaporation method which exhibited the inclusion of azelaic acid in the HPbetaCD cavity and gave the highest dissolution rate of azelaic acid was selected for the release study. Release studies of azelaic acid and this complex through the synthetic membranes were conducted using vertical Franz diffusion cells at 30 degrees C for 6 days. The release rates of azelaic acid through the synthetic membranes were enhanced by the formation of inclusion complex with HPbetaCD at the molar ratio of 1:1, with the increasing fluxes of about 41, 81 and 28 times of the uncomplexed system in cellophane, silicone and elastomer membranes, respectively. The result from this study can be applied for the development of azelaic acid for topical use.

Proximal tubule cells extract dicarboxylates from filtrate and blood, using cotransporters located in the brush border [sodium dicarboxylate cotransporter (NaDC-1)] and basolateral cell membrane (NaDC-3). We expressed the human NaDC-3 (hNaDC-3) in Xenopus laevis oocytes and characterized it by the two-electrode voltage-clamp technique. At -60 mV, succinate (4 carbons) and glutarate (5 carbons) generated inward currents due to translocation of three sodium ions and one divalent dicarboxylate, whereas oxalate (2 carbons) and malonate (3 carbons) did not. The cis-dicarboxylate maleate produced currents smaller in magnitude, whereas the trans-dicarboxylate fumarate generated currents similar to succinate. The substituted succinate derivatives, malate, 2,2- and 2,3-dimethylsuccinate, and 2,3-dimercaptosuccinate elicited inward currents, whereas aspartate and guanidinosuccinate showed hardly detectable currents. The C-5 dicarboxylates glutarate and alpha-ketoglutarate produced larger currents than succinate; glutamate and folate failed to cause inward currents. Kinetic analysis revealed, at -60 mV, K(0.5) values of 25 +/- 12 microM for succinate and 45 +/- 13 microM for alpha-ketoglutarate, values close to the plasma concentration of these compounds. For both compounds, the K(0.5) was independent of voltage, whereas the maximal current increased with hyperpolarization. As opposed to the rat and flounder orthologs, hNaDC-3 was hardly inhibited by lithium concentrations up to 5 mM. In the absence of sodium, however, lithium can mediate succinate-dependent currents. The narrow substrate specificity prevents interaction of drugs with dicarboxylate-like structure with hNaDC-3 and ensures sufficient support of the proximal tubule cells with alpha-ketoglutarate for anion secretion via organic anion transporter 1 or 3.

The aim of this study was to report the pharmacokinetic interaction between oltipraz (50 mg kg(-1)) and dimethyl-4,4'-dimethoxy-5,6,5',6'-dimethylene dioxybiphenyl-2,2'-dicarboxylate (DDB, 10 mg kg(-1)) after single intravenous and oral administration to rats. After intravenous administration of oltipraz plus DDB, the area under the plasma concentration-time curve from time zero to time infinity (AUC) of oltipraz was significantly greater (1440 vs 1740 microg min mL(-1)) than that after oltipraz alone. This was not due to slower clearances of oltipraz after oltipraz plus DDB since the total body, renal and nonrenal clearances were comparable between the two groups of rats. It could be due to a decrease in tissue binding of oltipraz by DDB. The apparent volume of distribution at steady state (Vd(ss)) of DDB was significantly smaller (7060 vs 4650 mL kg(-1)) than after oltipraz alone. After oral administration of oltipraz plus DDB, the AUC of olitpraz was also significantly greater (479 vs 583 microg min mL(-1)) than that after oltipraz alone. This was not due to increased absorption of oltipraz from the rat gastrointestinal tract after oltipraz plus DDB but again could be due to a decrease in Vd(ss) of oltipraz by DDB. However, after both intravenous and oral administration, the pharmacokinetic parameters of DDB were comparable between DDB alone and DDB plus oltipraz, indicating that oltipraz did not greatly affect the pharmacokinetics of DDB in rats.

A controlled porosity osmotic pump-based drug delivery system has been described in this study. Unlike the elementary osmotic pump (EOP) which consists of an osmotic core with the drug surrounded by a semipermeable membrane drilled with a delivery orifice, controlled porosity of the membrane is accomplished by the use of different channeling agents in the coating. The usual dose of pseudoephedrine is 60 mg to be taken three or four times daily. It has a short plasma half life of 5-8 h. Hence, pseudoephedrine was chosen as a model drug with an aim to develop a controlled release system for a period of 12 h. Sodium bicarbonate was used as the osmogent. The effect of different ratios of drug:osmogent on the in-vitro release was studied. Cellulose acetate (CA) was used as the semipermeable membrane. Different channeling agents tried were diethylphthalate (DEP), dibutylphthalate (DBP), dibutylsebacate (DBS) and polyethyleneglycol 400 (PEG 400). The effect of polymer loading on in-vitro drug release was studied. It was found that drug release rate increased with the amount of osmogent due to the increased water uptake, and hence increased driving force for drug release. This could be retarded by the proper choice of channeling agent in order to achieve the desired zero order release profile. Also the lag time seen with tablets coated using diethylphthalate as channeling agent was reduced by using a hydrophilic plasticizer like polyethyleneglycol 400 in combination with diethylphthalate. This system was found to deliver pseudoephedrine at a zero order rate for 12 h. The effect of pH on drug release was also studied. The optimized formulations were subjected to stability studies as per ICH guidelines at different temperature and humidity conditions.

This study explores the potential of the monoglyceride monocaprin as an enhancer of the epithelial permeability of the beta(3)-adrenoceptor agonist BTA-243, as an approach to improving the bioavailability of this drug. The permeabilities of BTA-243 and mannitol (paracellular marker) in Caco-2 cell monolayer and everted gut sac models in aqueous buffer (pH 6.8) in the presence of 1.3 and 2.0 mM monocaprin were compared with control (monocaprin-free) solutions over a period of 1 h. The transepithelial electrical resistance (TEER) of the Caco-2 cell monolayers was measured at regular time intervals throughout the experiment and after a recovery period of 30 h. Toxicological damage to the biological models associated with exposure to monocaprin was assessed by scanning electron microscopy and by the measurement of lactate dehydrogenase (LDH) release from everted gut sacs. The permeability of BTA-243 in epithelial monolayers was enhanced in the presence of 1.3 and 2.0 mM monocaprin. Measurements of TEER and mannitol permeability showed partial recovery of barrier properties after a 30 h period following exposure to 1.3 mM monocaprin. No structural damage was evident in these monolayers. Enhancement of Caco-2 permeability to BTA-243 by 2.0 mM monocaprin was significantly greater than by 1.3 mM but was irreversible; monolayers failed to recover their barrier properties after 30 h and changes in their gross morphology were observed. The mucosal to serosal transfer of BTA-243 in everted gut sac was enhanced but to a lesser extent than in the Caco-2 model. LDH release from everted gut sacs exposed to monocaprin was significantly less than that after exposure to Triton X-100, a nonionic surfactant known to cause membrane disruption.

The recognition properties of a cooperative pinwheel chemosensor for dicarboxylates are described. The sensor possesses four guanidinium recognition elements to cooperatively bind two dicarboxylates of varying size. The effect of cooperativity and the read-out mechanism contributes to favorable binding constants for dicarboxylates in water, as well as a high degree of selectivity over monocarboxylates. Appropriate methods of reporting affinity for cooperative systems are discussed.

Transport and metabolism of dicarboxylates may be important in the glial-neuronal metabolic interplay. Further, exogenous dicarboxylates have been suggested as cerebral energy substrates. After intrastriatal injection of [(14) C]fumarate or [(14) C]malate, glutamine attained a specific activity 4.1 and 2.6 times higher than that of glutamate, respectively, indicating predominantly glial uptake of these four-carbon dicarboxylates. In contrast, the three-carbon dicarboxylate [(14) C]malonate gave a specific activity in glutamate which was approximately five times higher than that of glutamine, indicating neuronal uptake of malonate. Therefore, neurones and glia take up different types of dicarboxylates, probably by different transport mechanisms. Labelling of alanine from [(14) C]fumarate and [(14) C]malate demonstrated extensive malate decarboxylation, presumably in glia. Intravenous injection of 75 micromol [U-(13) C]fumarate rapidly led to high concentrations of [U-(13) C]fumarate and [U-(13) C]malate in serum, but neither substrate labelled cerebral metabolites as determined by (13) C NMR spectroscopy. Only after conversion of [U-(13) C]fumarate into serum glucose was there (13) C-labelling of cerebral metabolites, and only at <10% of that obtained with 75 micromol [3-(13) C]lactate or [2-(13) C]acetate. These findings suggest a very low transport capacity for four-carbon dicarboxylates across the blood-brain barrier and rule out a role for exogenous fumarate as a cerebral energy substrate.

A stable cell line expressing the predominant brain glutamate transporter EAAT2 was used for the characterization of substrate exchange as a biochemical index for discriminating between substrate and non-substrate inhibitors of the cloned EAAT2 transporter. Addition of 1 mM unlabeled D-aspartate to cells equilibrated with [3H]D-aspartate produced a time-dependent depletion of the [3H] label retained by the cells. L-Aspartate, L-glutamate and L-cysteate produced an equivalent degree of [3H] exchange to that observed with D-aspartate, although the non-substrate EAAT2 inhibitor dihydrokainate and D-glutamate, which does not interact with the substrate binding site, failed to stimulate [3H]D-aspartate exchange. Estimation of EC50 values for the stimulation of [3H] exchange by D-aspartate, L-glutamate and L-trans-2,4-pyrollidine carboxylate (trans-PDC) produced values that were in excellent agreement with the corresponding IC50 values for the same compounds to inhibit EAAT2 uptake. Moreover, trans-PDC was found to produce a lower maximal exchange than that observed with D-aspartate, consistent with the known partial EAAT2 substrate activity of trans-PDC. The estimate of drug induced [3H] efflux with the cloned EAAT2 transporter represents a convenient biochemical assay for the discrimination of substrate and non-substrate inhibitors of the EAAT2 subtype., (Copyright 2001 Wiley-Liss, Inc.)

N-Acetylaspartate is a highly specific marker for neurons and is present at high concentrations in the central nervous system. It is not present at detectable levels anywhere else in the body other than brain. Glial cells express a high-affinity transporter for N-acetylaspartate, but the molecular identity of the transporter has not been established. The transport of N-acetylaspartate into glial cells is obligatory for its intracellular hydrolysis, a process intimately involved in myelination. N-Acetylaspartate is a dicarboxylate structurally related to succinate. We investigated in the present study the ability of NaDC3, a Na(+)-coupled high-affinity dicarboxylate transporter, to transport N-acetylaspartate. The cloned rat and human NaDC3s were found to transport N-acetylaspartate in a Na(+)-coupled manner in two different heterologous expression systems. The Michaelis-Menten constant for N-acetylaspartate was approximately 60 microM for rat NaDC3 and approximately 250 microM for human NaDC3. The transport process was electrogenic and the Na(+):N-acetylaspartate stoichiometry was 3:1. The functional expression of NaDC3 in the brain was demonstrated by in situ hybridization and reverse transcription-polymerase chain reaction as well as by isolation of a full-length functional NaDC3 from a rat brain cDNA library. In addition, the expression of a Na(+)-coupled high-affinity dicarboxylate transporter and the interaction of the transporter with N-acetylaspartate were demonstrable in rat primary astrocyte cultures. These studies establish NaDC3 as the transporter responsible for the Na(+)-coupled transport of N-acetylaspartate in the brain. This transporter is likely to be an essential component in the metabolic role of N-acetylaspartate in the process of myelination.

The extracellular glutamate concentration ([glu](o)) rises during cerebral ischemia, reaching levels capable of inducing delayed neuronal death. The mechanisms underlying this glutamate accumulation remain controversial. We used N-methyl-D-aspartate receptors on CA3 pyramidal neurons as a real-time, on-site, glutamate sensor to identify the source of glutamate release in an in vitro model of ischemia. Using glutamate and L-trans-pyrrolidine-2,4-dicarboxylic acid (tPDC) as substrates and DL-threo-beta-benzyloxyaspartate (TBOA) as an inhibitor of glutamate transporters, we demonstrate that energy deprivation decreases net glutamate uptake within 2-3 min and later promotes reverse glutamate transport. This process accounts for up to 50% of the glutamate accumulation during energy deprivation. Enhanced action potential-independent vesicular release also contributes to the increase in [glu](o), by approximately 50%, but only once glutamate uptake is inhibited. These results indicate that a significant rise in [glu](o) already occurs during the first minutes of energy deprivation and is the consequence of reduced uptake and increased vesicular and nonvesicular release of glutamate.

The disposition of dodecanedioic acid (C12) was investigated in six overnight-fasting healthy male volunteers, who received a 165-min i. v. infusion of 42.45 mmol of C12 added to 150 microCi of [1-12-(14)C]C12. Blood samples were collected up to 360 min after the start of infusion, and concentration of serum labeled C12 was determined. Expired radioactivity (microCi/min) was measured up to 600 min and at 24 h. The 24-h C12 urinary excretion was around 5% of the administered amount. The percentage of C12 oxidized was 81.7 +/- 9.5% (mean +/- S.D.) of administered amount as estimated from the area under the curve of measured (14)CO(2) expiration rate. C12 kinetics was described by assuming a single compartment. A saturable rate of C12 tissue uptake (model A) and a linear rate of tissue uptake (model B) were considered. The kinetics of CO(2) produced by C12 oxidation was described by a fast pathway acting in parallel to a slow pathway modeled by first order kinetics. Parameters of model B were estimated for each subject, whereas model A was identified by fitting the pooled data of all subjects. On the basis of estimates obtained from model B, an average calorie delivery of 500 kcal/day was predicted in the plateau phase for the infusion rate of our experiments. When estimated from model A, the maximal rate of tissue uptake was 0.38 +/- 0.08 mmol/min, with a maximal calorie delivery of 750 kcal/day. These results appear promising for C12 utilization in parenteral nutrition, because C12 elimination with urine is low, whereas tissue uptake and oxidation are rather efficient.