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Artemisinin-based combination therapies (ACTs) have been adopted as the first line of treatment against malaria in nearly all malaria-endemic countries, mainly as a result of Plasmodium falciparum infection, as this species of malaria parasite has developed resistance to most of the available non-artemisinin antimalarial drugs. Artemisinin-naphthoquine (ART-NQ, also named as ARCO™; Kunming Pharmaceuticals, Kunming, China) is one of the several currently available ACTs that show a promising approach to dealing with drug-resistant malaria rather than monotherapies. Unlike other ACTs, ART-NQ requires either a single-dose treatment or a two-dose treatment within 24 h against uncomplicated P. falciparum malaria; however, this was mainly validated in adults rather than children. Batty et al. performed the first pharmacokinetic study of ART-NQ combination therapy for uncomplicated pediatric malaria, and the authors' results are described and discussed below.

Purpose: The purpose of this analysis was to investigate the pharmacokinetics (PK) of sepantronium (YM155), a small-molecule suppressor of the expression of the antiapoptosis protein survivin, in Japanese patients with advanced solid tumors and to evaluate the effect of renal impairment on the PK profile of sepantronium., Methods: Sepantronium was administered as a continuous intravenous infusion of 1.8-10.6 mg/m(2)/day for 168 h (7 days) to 33 patients. PK parameters were estimated via non-compartmental method. Renal function was categorized for the analysis based on the chronic kidney disease guidance using eGFR values at pre-dose., Results: The PK of sepantronium was dose proportional in the dose range of 1.8-10.6 mg/m(2)/day. Age and sex did not significantly affect the PK of sepantronium. Results suggested that total clearance and renal clearance in patients with moderate renal impairment were 0.7-fold lower than those in patients with normal renal function, resulting in 1.3-fold higher steady-state concentration and area under the curve values. The PK parameters of sepantronium in patients with mild renal impairment were comparable to those in the patients with normal renal function., Conclusions: While age and sex did not significantly affect the PK of sepantronium, moderate renal impairment increased exposure of sepantronium by about 30 %. The results suggest that no dose adjustment is required for patients with mild renal impairment.

Introduction: Various shortcomings of the available methods of extraction of plumbagin from Plumbago zeylanica using non-edible organic solvents coupled with the poor aqueous solubility and low bioavailability called for extracting plumbagin in a water soluble form via a single step technique using hydrophilic lipid Gelucire 44/14., Methods: Gelucire extract of P. zeylanica (GPZ) was prepared and evaluated for extraction efficiency, High-performance thin layer chromatography (HPTLC) and thermal analysis. In vitro intestinal absorption and bioavailability of plumbagin from GPZ in comparison with that of aqueous (APZ), ethanolic extract (EPZ) and standard plumbagin studied using non-everted rat intestinal sac model., Results: The GPZ showed significantly higher extraction efficiency (3.24±0.12% w/w) compared to ethanolic (EPZ) and aqueous (APZ) extraction, 2.48±0.16% w/w and 0.07±0.02% w/w respectively. GPZ displayed significantly higher Q(30min) (cumulative percentage absorption of plumbagin in 30 min) and lower t(40%) (time required for 40% w/w drug absorption). The flux and apparent permeability coefficient in duodenum and ileum were 2, 3 and 6 fold higher than EPZ, standard plumbagin and APZ respectively., Discussion: Improved therapeutic efficacy of plumbagin may be due to the micellar solubilization and consequent enhanced partitioning of plumbagin through intestinal by Gelucire which was reflected in the in vivo anti-inflammatory study conducted in rats., Conclusion: Thus extraction using Gelucire can be proclaimed as an efficient, economic and solvent-free technique for extraction of plumbagin and can be utilized for various clinically important water insoluble phytoconstituents in order to improve their biopharmaceutical properties., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Artemisinin-naphthoquine (ART-NQ) is a coformulated antimalarial therapy marketed as a single-dose treatment in Papua New Guinea and other tropical countries. To build on limited knowledge of the pharmacokinetic properties of the components, especially the tetra-aminoquinoline NQ, we studied ART-NQ disposition in Papua New Guinea children aged 5 to 12 years with uncomplicated malaria, comparing a single dose (15 and 6 mg/kg of body weight) administered with water (group 1; n = 13), a single dose (22 and 9 mg/kg) with milk (group 2) (n = 17), and two daily doses of 22 and 9 mg/kg with water (group 3; n = 16). The plasma NQ concentration was assayed by high-performance liquid chromatography, and the plasma ART concentration was assayed using liquid chromatography-mass spectrometry. Population-based multicompartment pharmacokinetic models for NQ and ART were developed. NQ disposition was best characterized by a three-compartment model with a mean absorption half-life (t(1/2)) of 1.0 h and predicted median maximum plasma concentrations that ranged as high as 57 μg/liter after the second dose in group 3. The mean NQ elimination t(1/2) was 22.8 days; clearance relative to bioavailability (CL/F) was 1.1 liters/h/kg; and volume at steady state relative to bioavailability (V(ss)/F) was 710 liters/kg. Administration of NQ with fat (8.5 g; 615 kJ) versus water was associated with 25% increased bioavailability. ART disposition was best characterized by a two-compartment model with a mean CL/F (4.1 liters/h/kg) and V/F (21 liters/kg) similar to those of previous studies. There was a 77% reduction in the bioavailability of the second ART dose (group 3). NQ has pharmacokinetic properties that confirm its potential as an artemisinin partner drug for treatment of uncomplicated pediatric malaria.

YM155 monobromide is a novel small-molecule survivin suppressant. The pharmacokinetics, distribution and excretion of YM155/[14C]YM155 were investigated using males and pregnant or lactating female rats after a single intravenous bolus administration. For the 0.1, 0.3 and 1 mg/kg YM155 doses given to male rats, increases in area under the plasma concentration-time curves were approximately proportional to the increase in the dose level. After administering [14C]YM155, radioactivity concentrations in the kidney and liver were highest among the tissues in both male and pregnant rats: e.g. 14.8- and 5.24-fold, respectively, and higher than in plasma at 0.1 h after dosing to male rats. The YM155 concentrations in the brain were lowest: 25-fold lower than in plasma. The transfer of radioactivity into fetuses was low (about 2-fold lower than in plasma). In lactating rats, the radioactivity was transferred into milk at a level 8- to 21-fold higher than for plasma. Radioactivity was primarily excreted in feces (64.0%) and urine (35.2%). The fecal excretion was considered to have occurred mainly by biliary excretion and partly by secretion across the gastrointestinal membrane from the blood to the lumen., (Copyright © 2012 John Wiley & Sons, Ltd.)

Dioncoquinones belong to a family of natural naphthoquinone products of interest due to their promising anti-tumoral and anti-infective activities. In particular, dioncoquinones A (5) and B (6) have been shown to be highly active against Leishmania major and multiple myeloma cells without any significant toxicity toward normal blood cells. Their effective concentrations against multiple myeloma cell lines were similar to those of melphalan, a well known DNA-alkylating agent used in a standard therapy against B cell lymphoma and multiple myeloma. We report on the first total synthesis of the highly oxygenated anti-tumoral agent dioncoquinone B (6) and the isolation of its new, even higher-oxygenated analogs, dioncoquinones C (7), D (8), and E (9), from cell cultures of Triphyophyllum peltatum. In addition, several derivatives of these compounds were synthesized, including dioncoquinone C (7), and a small library of naphthoquinones was created. Furthermore, the first structure-activity relationship (SAR) study on this class of compounds was conducted, showing that each of the three hydroxy groups, at C-3, C-5, and C-6, is required for improved anti-tumoral activities and decreased cytotoxicities., (Copyright © 2011 Elsevier Masson SAS. All rights reserved.)

Context and Objective: Plumbagin (2-methyl, 5-hydroxy, 1, 4-naphthoquinone), an anticancer agent is encapsulated either as conventional or long circulating liposomal formulations to enhance its biological half-life and antitumor efficacy., Methods: The liposomes were prepared by thin film hydration method and in vitro characterization was carried out to examine the particle size, zeta potential, drug encapsulation efficiency and in vitro release. The optimized formulations were tested for pharmacokinetic and pharmacodynamic efficacy against mice bearing B16F1 melanoma. Also in vivo toxicity studies were carried out., Results and Discussion: The optimum particle size and entrapment efficiency was observed at drug to lipid molar ratio of 1:20. The in-vitro release of plumbagin from the liposomal formulations in phosphate-buffered saline (pH 7.4) showed biphasic release with an initial burst release followed by sustained release phase. Elimination half life (T(½)) of pegylated, conventional and free plumbagin was 1305.76 ± 278.16, 346.87 ± 33.82 and 35.89 ± 7.95 min respectively. Further, plumbagin exhibited better antitumor efficacy in vivo when administered as long circulating liposomes with no signs of normal tissue toxicity., Conclusion: It can be concluded that the pegylated liposomes could provide a promising parenteral platform for plumbagin with enhanced plasma half-life and therapeutic efficacy.

Objectives: The purpose of this work was to study the chemical stability of the new antitumoral β-lapachone (βLAP) to determine the degradation pathway/s of the molecule and the degradation kinetics in addition to identifying several degradation products., Method: Samples of βLAP in solution were stored under conditions of darkness and illumination at 40°C at which the pseudo-first order rate constants for the βLAP degradation were determined. Furthermore, drug degraded solutions were concentrated and purified using Sephadex LH-20 and preparative thin-layer chromatography and degradation products were identified by nuclear magnetic resonance spectroscopy., Key Findings: The results revealed that βLAP shows two different degradation routes: hydrolysis in the dark and photolysis under the light. The βLAP exposure to light accelerated the drug degradation about 140 fold, compared with the samples stored in the absence of light. The hydrolysis produced hydroxylapachol as the main degradation product. The photolysis yielded phthalic acid, 6-hydroxy-3methylene-3H-isobenzofuran-1-one and a benzomacrolactone together with a complex mixture of other phthalate-derivatives such as 2-(2-carboxy-acetyl)-benzoic acid., Conclusions: This study provides useful information for the development of βLAP dosage forms, their storage, manipulation and quality control., (© 2011 The Authors. JPP © 2011 Royal Pharmaceutical Society.)

The present study was aimed to formulate and compare the pharmacokinetic, biodistribution, pharmacodynamic, and toxicity profiles of free 5-hydroxy-1,4-naphthoquinone (juglone) with sterically stabilized liposomal form. The liposomes were optimized for size, zeta potential, entrapment efficiency (EE), and in vitro release properties. The optimized formulation had a mean size, zeta potential, and EE value of 137.1 nm, -43.1 mV, and 67.2%, respectively. In vitro release studies showed biphasic pattern with initial burst followed by sustained release over the study period, releasing about 61% after 24 h. In vitro cytotoxicity studies against melanoma cells indicated that liposomal juglone was more toxic than free juglone. Free juglone had short plasma half-life of about 2 h, whereas liposomal juglone exhibited significantly improved pharmacokinetics with a 12-fold increase in plasma half-life. Further, biodistribution studies indicated rapid renal elimination of free juglone, evidenced by its significant localization in kidneys. Conversely, the accumulation of liposomal juglone in kidneys reduced significantly with enhanced tumor localization, thereby resulting in enhanced antitumor activity. The histological studies revealed lower levels of nephrotoxicity for liposomal juglone compared with that of free juglone. To conclude, sterically stabilized liposomes could be a promising approach for the intravenous delivery of hydrophobic compounds such as juglone., (Copyright © 2011 Wiley-Liss, Inc.)

Quinone toxicity is induced by two principal mechanisms: arylation/alkylation and a redox cycle. We have previously shown that increases in intracellular levels of superoxide anion and cell death induced by 2,3-dimethoxy-1,4-naphthoquinone (DMNQ), a redox cycling quinone, are enhanced by pretreatment of rat primary hepatocytes with cytochrome P450 inhibitors. This indicates a novel interaction of quinones with cytochrome P450, and is thus worthy of further investigation using an in vivo model. The aim of this study was to examine the effects of cytochrome P450 inhibitors on DMNQ-induced hepatotoxicity in rats. When DMNQ was administered intraperitoneally, the activities of serum alanine aminotransferase and aspartate aminotransferase were found to increase in a dose-dependent manner, indicating that hepatotoxicity was induced by treatment with DMNQ. Pretreatment with the cytochrome P450 inhibitors SKF-525A (SKF), cimetidine and ketoconazole potentiated the DMNQ-induced hepatotoxicity. The blood concentration of DMNQ was not affected by administration of SKF. Pretreatment with the antioxidant α-tocopherol almost completely attenuated the hepatotoxicity induced by DMNQ and by the combination of DMNQ with SKF. Levels of reduced glutathione in the liver were decreased and levels of oxidized glutathione were increased by treatment with DMNQ. These effects were potentiated by pretreatment with SKF. DMNQ-induced lipid peroxidation in the liver was also enhanced by pretreatment with SKF. Taken together, these results indicate that DMNQ-induced hepatotoxicity is augmented by inhibition of cytochrome P450 and that this augmentation is due to the enhancement of oxidative stress., (Copyright © 2010 John Wiley & Sons, Ltd.)

The compound naphthoquine phosphate is a novel antimalaria drug tablet containing a fixed-dose combination of naphthoquine phosphate and artemisinin in a 1:2.5 ratio. A randomized, open study on the safety and tolerability was conducted in 28 healthy male volunteers using a single oral dose of 350 mg, 700 mg, 1400 mg, or 2100 mg of artemisinin-naphthoquine phosphate. Pharmacokinetics at the last 3 doses were examined in 30 volunteers. Food effects were also determined. Serial blood samples up to 216 hours after single oral dose administration were analyzed for plasma concentrations using a validated high-performance liquid chromatography-tandem mass spectrometry assay. The compound was well tolerated at single doses up to 2100 mg. Increased exposure to naphthoquine phosphate and artemisinin was less than dose proportional and linear. The half-life of naphthoquine phosphate was approximately 255 hours. The combination increased the AUC(0-t) and C(max) of both artemisinin (by 71% and 49%) and naphthoquine phosphate (by 135% and 104%) compared with monotherapy. Food intake greatly increased the AUC(0-t) of artemisinin with a ratio of 77% and reduced that of naphthoquine phosphate from 955 ± 352 µg·h/L under the fasted state to 446 ± 231 µg·h/L in the fed condition. The pharmacokinetics and safety profile of the drug support its continued investigation in future clinical studies.

Lung cancer is the leading cause of cancer-related deaths with current chemotherapies lacking adequate specificity and efficacy. Beta-lapachone (beta-lap) is a novel anticancer drug that is bioactivated by NAD(P)H:quinone oxidoreductase 1, an enzyme found specifically overexpressed in non-small cell lung cancer (NSCLC). Herein, we report a nanotherapeutic strategy that targets NSCLC tumors in two ways: (a) pharmacodynamically through the use of a bioactivatable agent, beta-lap, and (b) pharmacokinetically by using a biocompatible nanocarrier, polymeric micelles, to achieve drug stability, bioavailability, and targeted delivery. Beta-lap micelles produced by a film sonication technique were small ( approximately 30 nm), displayed core-shell architecture, and possessed favorable release kinetics. Pharmacokinetic analyses in mice bearing subcutaneous A549 lung tumors showed prolonged blood circulation (t(1/2), approximately 28 h) and increased accumulation in tumors. Antitumor efficacy analyses in mice bearing subcutaneous A549 lung tumors and orthotopic Lewis lung carcinoma models showed significant tumor growth delay and increased survival. In summary, we have established a clinically viable beta-lap nanomedicine platform with enhanced safety, pharmacokinetics, and antitumor efficacy for the specific treatment of NSCLC tumors., ((c)2010 AACR.)

The present study was aimed to evaluate the anti-tumor efficacy and systemic toxicity of chitosan-based plumbagin microspheres in comparison to free plumbagin. The optimized formulation had a mean particle size of 106.35 mum with an encapsulation efficiency of 80.12%. Pharmacokinetic studies showed a 22.2-fold increase in elimination half-life (t(1/2)) of plumbagin from chitosan microspheres as compared to free plumbagin. Administration of plumbagin microspheres resulted in a significant tumor growth inhibition and reduced systemic toxicity. These results suggest that chitosan-based microspheres could be a promising strategy for the systemic delivery of anti-cancer agents like plumbagin.

A new, fast and sensitive high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC/ESI-MS/MS) method was developed and validated for isovalerylshikonin in rat plasma using emodin as internal standard (IS). The analyte was extracted from rat plasma with ethyl acetate, after 10% HCl treatment and protein precipitated by methanol. The compound was separated on an Ultimate XB-C(18) analytical column using a mobile phase of methanol-10 mM ammonium acetate in water-acetonitrile containing 0.05% formic acid (45 : 10 : 45, v/v/v) with isogradient elution. The analyte was detected in negative ion mode using multiple-reaction monitoring. The method was validated and the specificity, linearity, lower limit of quantitation (LLOQ), precision, accuracy, recoveries and stability were determined. LLOQ was 9 ng/mL for isovalerylshikonin. Correlation coefficient (r) value for the linear range of the analyte was greater than 0.99. The intra-day and inter-day precision and accuracy were better than 8.52%. The relative and absolute recovery was above 86% and no matrix effects were observed for isovalerylshikonin. This validated method provides a modern, rapid and robust procedure for the pharmacokinetic study of the two compounds in rats after intravenous administration to rats (n = 4)., (Copyright (c) 2009 John Wiley & Sons, Ltd.)

Purpose: YM155, a novel molecular targeted agent, suppresses survivin, a member of the inhibitor of apoptosis protein family that is overexpressed in many tumor types. The aim of this study was to determine the maximum tolerated dose (MTD) and to assess the safety, pharmacokinetics, and antitumor activity of YM155 in patients with advanced refractory solid tumors., Experimental Design: Patients with advanced refractory solid tumors were treated with escalating doses of YM155 administered by continuous i.v. infusion for 168 hours in 21-day cycles., Results: Of the 34 patients enrolled, 33 (median age, 59 years) received at least 1 dose of YM155 (range, 1-19 cycles). The dose levels studied were 1.8, 3.6, 4.8, 6.0, 8.0, and 10.6 mg/m(2)/d. The MTD was determined to be 8.0 mg/m(2)/d, based on a dose-limiting toxicity of increased blood creatinine observed in 2 patients receiving 10.6 mg/m(2)/d. The most common adverse reactions judged to be related to YM155 were urine microalbumin present; fever; injection-site phlebitis; fatigue; and decreased hemoglobin/anemia, blood albumin, and lymphocyte count. The pharmacokinetic profile was almost linear over the dosing range and was similar between cycles 1 and 2. Urinary excretion of YM155 showed no definite difference among doses. Stable disease was achieved in nine patients., Conclusions: YM155 was safely administered to patients with advanced refractory solid tumors by 168-hour continuous i.v. infusion in 21-day cycles. The MTD was determined to be 8.0 mg/m(2)/d. The safety profile, plasma concentrations achieved, and antitumor activity observed merit further studies with this survivin suppressant, alone and in combination regimens.

A sensitive and selective liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed and validated for the determination of beta,beta-dimethylacrylshikonin (DASK) in rat whole blood. DASK was pretreated using pre-column derivatization with 2-mercaptoethanol followed by liquid-liquid extraction with cyclohexane. Detection was performed on Thermo Finnigan TSQ Quantum triple quadrupole mass spectrometer by selected reaction monitoring mode via electrospray ionization source. The linear range for the determination of DASK spiked in rat whole blood (0.25 mL) was 3-3000 ng/mL. The accuracy was within 9%. Intra- and inter-day precisions were no more than 16.1 and 13.3%, respectively. The validated LC-MS/MS method was successfully applied to the preliminary pharmacokinetic study in rats. After DASK administration (60 mg/kg, p.o.) in rats, pharmacokinetic parameters were obtained, where the area under the drug concentration-time curve was 2393.7 +/- 224.4 ng h/mL and the elimination half-life was 27.6 +/- 5.3 h.

2,3-dimethoxy-1,4-naphthoquinone (CAS-RN 6959-96-3) (DMNQ) and 2-methyl-1,4-naphthoquinone (CAS-RN 58-27-5) (MNQ:menadione) are effective one electron redox cycling chemicals in vitro. In addition, in vitro MNQ forms a thioether conjugate with glutathione by nucleophilic attack at the third carbon. In contrast, here we demonstrate that in vivo the major metabolic route is directly to the dihydronaphthoquinone for both DMNQ and MNQ followed by conjugation to mono- and di-glucuronides and sulfate. Analysis of urine and bile showed that glutathione conjugation of MNQ was only a very minor route of metabolism. DMNQ was distributed to all tissues including the brain, and MNQ was much less widely distributed. For DMNQ tissue half-life, in particular for the heart, was considerably longer than the plasma half-life. For both DMNQ and MNQ, urine 8-oxo-7,8-dihydro-2'-deoxyguanosine and liver transcriptomic analysis failed to show any evidence of redox stress. Oxidized glutathione (GSSG) in liver increased significantly at the 10 min postdosing time point only. Metabonomic analysis 96 h after DMNQ administration indicated decreased liver glucose and increased lactate and creatine suggesting an impairment of oxidative metabolism. We conclude that in vivo DMNQ and MNQ are primarily two electron reduced to the dihydronaphthoquinones and undergo little one electron redox cycling. For DMNQ, disruption of cellular oxidative metabolism may be a primary mechanism of toxicity rather than redox stress.

1-(2-Methoxyethyl)-2-methyl-4,9-dioxo-3-(pyrazin-2-ylmethyl)-4,9-dihydro-1H-naphtho[2,3-d]imidazolium bromide (YM155 monobromide) is a novel small-molecule survivin suppressant that induces the down-regulation of survivin and exhibits potent antitumor activity in nude mice bearing the human hormone refractory prostate carcinoma cell line PC-3. In this study, radioluminographic determination of the in vivo distribution of radioactivity after administration of [(14)C]YM155 to PC-3-xenografted nude mice revealed a relatively high level of radioactivity in the PC-3 xenograft. Therefore, the uptake of [(14)C]YM155 was further characterized in vitro using PC-3, lung cancer (Calu-6 and NCI-H358), malignant melanoma (A375 and SK-MEL-5), and non-Hodgkin's lymphoma (RL and Ramos) cell lines. The uptake of [(14)C]YM155 in these cell lines was dependent on incubation time, temperature, and drug concentration. The Michaelis-Menten constant values were similar among the seven cell lines (0.189-0.367 microM). The effects of various compounds on the uptake of [(14)C]YM155 were tested in PC-3, Calu-6, A375, RL, and Ramos cell lines. Of the compounds tested, the cationic transporter substrates/inhibitors (tetraethylammonium, 1-methyl-4-phenylpyridium, cimetidine, prazosin, corticosterone, verapamil, amantadine, procainamide, and N-methylnicotinamide) inhibited the uptake of [(14)C]YM155 to a similar extent among the five cell lines. The half-maximal inhibitory concentration values (IC(50)) of several compounds for the uptake of [(14)C]YM155 into PC-3 differed from those reported in the literature for human organic cation transporter 1 (OCT1/SLC22A1), OCT2 (SLC22A2), and OCT3 (SLC22A3). To summarize, YM155 was taken up into cancer cells in a carrier-mediated manner and with a similar affinity among all the cancer cell lines tested. An influx transporter(s) may contribute to this process.

Purpose: To determine the maximum-tolerated dose (MTD) and assess the safety, pharmacokinetics, and preliminary evidence of antitumor activity of YM155, a small-molecule inhibitor of survivin., Patients and Methods: Patients with advanced solid malignancies or lymphoma were treated with escalating doses of YM155 administered by 168-hour continuous intravenous infusion (CIVI). Plasma and urine samples were assayed to determine pharmacokinetic parameters and excretion., Results: Forty-one patients received 127 cycles of YM155 at doses ranging from 1.8 to 6.0 mg/m(2)/d by 168-hour CIVI every 3 weeks. Overall, the most common grade 1 to 2 toxicities were stomatitis, pyrexia, and nausea, whereas grade 3 and 4 toxicities were rare. Reversible elevation in serum creatinine in two patients, with one developing acute tubular necrosis, was dose-limiting at 6.0 mg/m(2). The MTD was 4.8 mg/m(2). At the MTD, the mean steady-state concentration, clearance, volume of distribution at steady-state, and terminal elimination half-life were 7.7 ng/mL, 47.7 L/h, 1,763 L, and 26 hours, respectively. One complete and two partial responses lasting 8, 24+ and 48+ months occurred in three patients with non-Hodgkin's lymphoma, two patients with hormone- and docetaxel-refractory prostate cancer had prostate-specific antigen responses, and one patient with non-small-cell lung cancer had a minor response. CONCLUSION YM155 can be administered safely at 4.8 mg/m(2)/d 168 hours CIVI every 3 weeks. The absence of severe toxicities, attainment of plasma concentrations active in preclinical models, and compelling antitumor activity warrant further disease-directed studies of this agent alone and in combination with chemotherapy in a broad array of tumors.

A sensitive and specific LC-MS/MS method employing positive electrospray ionization for the determination of ARQ 501 (beta-lapachone) in (nu/nu) mouse plasma and tumor tissue is described. Samples were processed using protein precipitation with acetonitrile. A d6 analog of ARQ 501 was used as the internal standard (IS). The analytes were separated using a Zorbax SB8 column (30 mm x 2.1 mm i.d. 5 microm particle size) and analyzed in the multiple reaction monitoring (MRM) mode using mass transitions of 243>159 and 249>159 m/z for ARQ 501 and d6-ARQ 501, respectively. The lower limit of quantitation (LLOQ) for ARQ 501 was 3.0 ng/mL. The calibration curve was linear in the range of 3.0-2000 ng/mL with a correlation coefficient better than 0.99. Intra- and inter-batch precisions were within 8.4% for plasma and 11.8% for tumor samples. Accuracy expressed as percentage relative error (%R.E.) ranged from -9.0 to 7.7 for both plasma and tumor samples. Recovery was between 106 and 113% for both ARQ 501 and its d6 analog. Plasma pharmacokinetic data of ARQ 501 in mouse from intraperitoneal (IP) dosing at 60 mg/kg obtained using this validated method is presented along with tumor concentration data. The C(max), AUC(0-infinity), t(1/2), Cl/F, and V(d)/F were determined to be 4016 ng/mL, 4392 h ng/mL, 3.9 h, 13.7 L/h/kg, and 76.5 L/kg, respectively. Tumor tissue concentrations were in the range 1-2 microM for approximately 2 h post-dose.

This paper describes a sensitive and selective liquid chromatography with tandem mass spectrometry (LC-MS/MS) method for determination of the novel survivin suppressant YM155, 1-(2-methoxyethyl)-2-methyl-4,9-dioxo-3-(pyrazin-2-ylmethyl)-4,9-dihydro-1H-naphtho[2,3-d]imidazolium, which is developed for the treatment of solid tumors. This method uses a liquid-liquid extraction from 0.25 mL of dog plasma. LC separation was carried out on a Genesis Silica column (50 mm x 3.0 mm i.d.) at a flow-rate of 0.5 mL/min. Compounds were eluted using a mobile phase of 5 mm ammonium acetate and 0.1% formic acid in water-0.1% formic acid in acetonitrile, 17:83 (v/v). MS/MS detection was carried out with an MDS-Sciex API3000 triple quadrupole mass spectrometer in positive electrospray ionization mode. The standard curve was linear from 0.05 to 50 ng/mL (r > or = 0.9968). The lower limit of quantitation was 0.05 ng/mL. Good intra- and inter-day assay precision (within 7.4% RSD) and accuracy (within +/-12.3%) were obtained. The extraction recovery was 66.2%. The method was successfully applied to preclinical pharmacokinetic studies in dogs.

A simple, sensitive and specific reversed-phase high-performance liquid chromatographic method with UV detection at 251 nm was developed for quantitation of buparvaquone (BPQ) in human and rabbit plasma. The method utilizes 250 microL of plasma and sample preparation involves protein precipitation followed by solid-phase extraction. The method was validated on a C18 column with mobile phase consisting of ammonium acetate buffer (0.02 m, pH 3.0) and acetonitrile in the ratio of 18:82 (v/v) at a flow rate of 1.1 mL/min. The calibration curves were linear (correlation coefficient>or=0.998) in the selected range. The method is specific and sensitive with limit of quantitation of 50 ng/mL for BPQ. The validated method was found to be accurate and precise in the working calibration range. Stability studies were carried out at different storage conditions and BPQ was found to be stable. Partial validation studies were carried out using rabbit plasma and intra- and inter-day precision and accuracy were within 7%. This method is simple, reliable and can be routinely used for preclinical pharmacokinetic studies for BPQ., (Copyright (c) 2007 John Wiley & Sons, Ltd.)

Analysis of intraocular fluid and the vitreous body in 7 rabbits (14 eyes) by high performance liquid chromatography reveals histochrom metabolic products and, possibly, histrochrom itself during intravenous and subconjunctival injections and retrobulbar administration of histochrom through the irrigation system on models of experimental rabbit hyphema and hemophthalmia, which suggests that histochrom is able to penetrate across the blood-ocular barrier.

Naphthoquinones are wide-spread phenolic compounds in nature. They are products of bacterial and fungal as well as high-plants secondary metabolism. Juglone, lawsone, and plumbagin are the most widespread compounds. Naphthoquinones display very significant pharmacological properties--they are cytotoxic, they have significant antibacterial, antifungal, antiviral, insecticidal, anti-inflammatory, and antipyretic properties. Pharmacological effects to cardiovascular and reproductive systems have been demonstrated too. The mechanism of their effect is highly large and complex--they bind to DNA and inhibit the processes of replication, interact with numerous proteins (enzymes) and disturb cell and mitochondrial membranes, interfere with electrons of the respiratory chain on mitochondrial membranes. Plants with naphthoquinone content are widely used in China and the countries of South America, where they are applied to malignant and parasitic diseases treatment.

A simple, sensitive and specific reversed phase high performance liquid chromatographic (RP-HPLC) method with UV detection at 251 nm was developed for simultaneous quantitation of buparvaquone (BPQ), atenolol, propranolol, quinidine and verapamil. The method was applicable in rat in situ intestinal permeability study to assess intestinal permeability of BPQ, a promising lead compound for Leishmania donovani infections. The method was validated on a C-4 column with mobile phase comprising ammonium acetate buffer (0.02 M, pH 3.5) and acetonitrile in the ratio of 30:70 (v/v) at a flow rate of 1.0 ml/min. The retention times for atenolol, quinidine, propranolol, verapamil and BPQ were 4.30, 5.96, 6.55, 7.98 and 8.54 min, respectively. The calibration curves were linear (correlation coefficient > or =0.996) in the selected range of each analyte. The method is specific and sensitive with limit of quantitation of 15 microg/ml for atenolol, 0.8 microg/ml for quinidine, 5 microg/ml for propranolol, 10 microg/ml for verapamil and 200 ng/ml for BPQ. The validated method was found to be accurate and precise in the working calibration range. Stability studies were carried out at different storage conditions and all the analytes were found to be stable. This method is simple, reliable and can be routinely used for accurate permeability characterization.

Lawsone (2-hydroxy-1,4-naphthoquinone) is the principal color ingredient in henna, a color additive approved with limitations for coloring hair by the Food and Drug Administration (FDA) under 21 CFR 73.2190. In 2002, the scientific committee on cosmetics and non-food products (SCCNFP), now known as the scientific committee for consumer products (SCCP), evaluated the safety of lawsone as a coloring agent in hair dye products of the European Union (EU). The SCCNFP concluded that lawsone was mutagenic and not suitable for use as a hair coloring agent. As a result, studies were conducted to measure the extent of lawsone absorption through human skin. Lawsone skin absorption was determined from two hair coloring products and two shampoo products, all containing henna. [(14)C]-Lawsone (sp. act. 22.9 mCi/mmol) was added to each commercial product and the products were applied to dermatomed, nonviable human skin mounted in flow-through diffusion cells perfused with a physiological buffer (HEPES-buffered Hanks' balanced salt solution, pH 7.4). Products remained on the skin for 5 minutes (shampoos) and 1 hour (hair color paste). For the henna hair paste products, 0.3 and 1.3% of the applied dose was absorbed into the receptor fluid in 24 hours while 2.2 and 4.0% remained in the skin. For both henna shampoo products, 0.3% of the applied dose was absorbed into the receptor fluid at 24 hours while 3.6 and 6.8% remained in the skin. For all products, most of the lawsone applied was washed from the surface of the skin (83-102%) at the end of the exposure period. Extended absorption studies were conducted for 72 hours to determine if skin levels of lawsone in the 24 hour studies might eventually be percutaneously absorbed. These studies determined that the majority of the lawsone remained in the skin with only a small but significant increase (for three out of four products) in receptor fluid values. Therefore, it appears that receptor fluid values would give a good estimate of lawsone absorption for an exposure estimate and that skin levels of lawsone need not be included.

Basic Blue 99 is a direct, nonoxidative hair colorant used in temporary and semipermanent hair dyes. According to current reported usage data, Basic Blue 99 is used at concentrations from 0.004% to 2% and the most often reported use is in hair tints. Hair dyes containing Basic Blue 99, as "coal tar" hair dye products, are exempt from the principal adulteration provision and from the color additive provision of the Federal Food, Drug, and Cosmetic Act of 1938 when the label bears a caution statement and "patch test" instructions for determining whether the product causes skin irritation. Preliminary testing on or by individuals should be done using an open patch test that is evaluated at 48 h after application of the test material. Users, therefore, would be able to determine their individual reactions to hair dye products containing Basic Blue 99. Basic Blue 99 dye is approximately 60% to 63% dye, whereas the remainder of the mixture is composed of sugar ( approximately 25.7%), volatile matter/water crystallization ( approximately 1.8%), and inorganic salts (bringing the mixture to 100%). The dermal absorption of Basic Blue 99 is low in both rats and humans. The LD(50) values of Basic Blue 99 in mice and rats were 2.7 g/kg and between 1.0 g/kg and greater than 2.0 g/kg, respectively. Mice and rats orally administered Basic Blue 99 for 90 days did not show any indications of cumulative toxicity. Discoloration of organs involved in the elimination of Basic Blue 99 from the animals was noted in both test species. In rabbits, Basic Blue 99 did not cause ocular irritation, but some discoloration was noted. Basic Blue 99 caused minimal dermal irritation in rabbits. Sensitization occurred in animals exposed to Basic Blue 99 in a DMSO vehicle, but not in a water vehicle in guinea pigs and mice. Basic Blue 99 administered by gavage did not cause developmental toxicity in rats. Basic Blue 99 was a weak mutagen with and without metabolic activation in the Ames test, producing both reverse and frameshift mutations, but did not induce mutations in Escherichia coli or in any mammalian cells tested. In a modified repeated-insult patch test (RIPT), no volunteers had any reaction to Basic Blue 99 after a 1-h occlusive challenge. Case reports have documented positive patch test results to 1% Basic Blue 99 in three patients. A current review of the hair dye epidemiology literature identified that use of direct hair dyes, although not the focus in all investigations, appears to have little evidence of an association with cancer or other adverse events. The Panel recognizes that hair dye epidemiology studies do not address the safety of individual hair dyes. Based on the available safety test data on Basic Blue 99, however, the Panel determined that this ingredient would not likely have carcinogenic potential as used in hair dyes. The Cosmetic Ingredient Review Expert Panel concluded that Basic Blue 99 is safe as a hair dye ingredient in the practice of use and concentration as described in this safety assessment.

Lu xian cao (Hebra pyrolae) is a traditional Chinese medicine used for the treatment of several major diseases. Chimaphilin has been demonstrated one of the major active components in Lu xian cao by modern pharmacological studies. In this study, a liquid chromatography-mass spectrometry method for the determination of chimaphilin in rat plasma was developed and validated. The separation was carried out on a C18 column using methanol and water as mobile phase after the plasma sample was extracted with diethyl ether. Atmospheric pressure chemical ionization in negative ion mode and selected ion monitoring method were developed to determine [M]- at 186 and 210 for chimaphilin and benzil (internal standard), respectively. The lower limit of quantitation was 10 ng/ml and the calibration curve was linear (r>0.9964) over the concentration range 10-1000 ng/ml. The method was demonstrated reproducible and reliable with intra-day precision<11.5%, inter-day precision<7.6%, accuracy in the range of 88.4-113.0%, and mean extraction recovery excess of 83.0%, which were all calculated from the quality control samples at concentrations of 20, 100, and 500 ng/ml. The method was successfully applied to pharmacokinetic study of chimaphilin in rat plasma following oral administration of a 30-mg/kg dose of chimaphilin in Lu xian cao decoction to male Wistar rats.

The aim of the present study is to develop an automated blood sampling (ABS) method coupled to a liquid chromatography-tandem mass spectroscopy (LC-MS/MS) method to evaluate the oral bioavailability of plumbagin in a conscious freely moving rat. Plumbagin, an herbal ingredient, was isolated from Plumbago zeylanica L. The separation was performed using a reversed phase C18 (150mmx4.6mm I.D.; 5microm) column and was eluted with the mobile phase of water-acetonitrile (40:60, v/v) at a flow-rate of 0.8ml/min. Multiple reaction monitoring (MRM) was used to monitor the transition of the deprotonated molecule m/z 187 [MH](-) to the product ion m/z 159 [MHCO](-) for the plumbagin analysis. The calibration curve was linear over the concentration range of 10-2000ng/ml with a coefficient estimation of 0.995. The intra- and inter-day variations (% relative standard deviation; RSD and % bias) of the assay for rat plasma samples were less than 17%. The limit of detection and the limit of quantification were 5 and 10ng/ml, respectively. Recovery of plumbagin from the rat plasma was about 80%. This LC-MS/MS method has been validated to study the pharmacokinetics of plumbagin in rats. The oral bioavailability (AUC(PO)/Dose(PO))/(AUC(IV)/Dose(IV)) of plumbagin was about 38.7+/-5%.

Crude extracts of the marine hydroid Garveia annulata show potent inhibition of indoleamine 2,3-dioxygenase (IDO). Fractionation of the extract led to the identification of the new polyketides annulin C (1), 2-hydroxygarveatin E (4), garveatin E (5), and garvin C (9). Annulins A (2), B (3), and C (1) were found to be submicromolar inhibitors of IDO.

East Coast fever, caused by the protozoan parasite Theileria parva, kills about 600,000 cattle annually in Africa. The hydroxynaphthoquinone compound buparvaquone (BPQ) is curative. Sixteen calves were infected with T. parva. On manifestation of disease symptoms, eight were injected with the original (pioneer) BPQ product and eight with a test product containing BPQ. All 16 calves were cured by one injection of 2.5 mg BPQ/kg bodyweight. The concentration of BPQ in blood plasma was monitored by HPLC. The mean observed C(max) of BPQ was 0.229 and 0.253 microg/mL of plasma, the mean observed time to reach this concentration (T(max)) was 2.62 and 2.12 h and the AUC (area under curve) was 4.785 and 4.156 microg h/mL, respectively, for the pioneer and test product. Considerable variations occurred in the plasma concentration of BPQ within each group. They showed no relationship with either clinical or parasitological parameters following treatment.

Exogenous surfactants are increasingly used to enhance the dispersion properties of lipid-based formulations of poorly water-soluble drugs, yet their possible effects on formulation digestion and oral bioavailability in-vivo are not well documented. In this study, in-vitro dispersion and digestion experiments were conducted using formulations comprising a blend of long-chain glycerides, ethanol, a model poorly water-soluble drug (atovaquone), and a series of surfactants including Cremophor EL and a range of Pluronic surfactants (Pluronics L121, L61, L72, L43 and F68). Inclusion of Cremophor EL, a surfactant with a high hydrophilic-lipophilic balance (HLB), promoted complete digestion of the formulation and effective dispersion and solubilisation of the lipolytic products and co-administered drug. Surprisingly, formulations containing the Pluronic (L121) with the lowest HLB (0.5) equally effectively promoted digestion and drug solubilisation and a trend towards decreased digestion and drug solubilisation was observed with Pluronics of increasing HLB values. All formulations effectively prevented drug precipitation, suggesting possible utility in-vivo, and no correlation was evident between the ability of the formulations to self-emulsify on dispersion and to promote drug solubilisation on digestion. Subsequent assessment of the oral bioavailability of atovaquone after administration of formulations containing Cremophor EL or Pluronic L121 or a simple solution of atovaquone in long-chain glycerides confirmed the utility of lipid-based formulations for enhancing the oral bioavailability of poorly water-soluble drugs such as atovaquone, but also indicated that in some cases microemulsion preconcentrate formulations may not provide additional bioavailability benefits beyond that achievable using simple lipid solutions.

The metabolism and disposition of 14C-labelled juglone in male F344 rats following oral, intravenous and dermal administration were studied. Approximately 40-50% of an oral dose (0.1 to 10 mg kg-1) and less than 20% of the dermal dose (4 mg kg-1) were absorbed within 24 h. Most of the oral dose was excreted in faeces and urine within 24 h and only 1-3% remained in the tissues. High concentrations of juglone-derived radioactivity were found in kidney for all three dosing routes. The accumulation in kidney can be attributed to covalent binding of juglone and/or metabolites to cytosolic protein. Five metabolites were identified in the urine of rats treated with an oral dose: 1,4,5-trihydroxynaphthalene di-glucuronide, 1,4,5-trihydroxynaphthalene mono-glucuronide mono-sulfate, 2-sulfo-2,3-dihydrojuglone, 4,8-dihydroxy-1-tetralone mono-glucuronide and 1,4,5-trihydroxynaphthalene mono-glucuronide. Liver microsomal incubations of juglone in the presence of NAD(P)H and UDP-glucuronic acid gave rise to two 1,4,5-trihydroxynaphthalene mono-glucuronides.

Objective: To investigate the pharmacokinetics, safety and efficacy of the recommended 3-day treatment regimen of Malarone in third-trimester pregnant women with acute uncomplicated falciparum malaria., Methods: Twenty-six pregnant women in their third trimester (gestational age: 24-34 weeks) with acute uncomplicated Plasmodium falciparum malaria who fulfilled the enrollment criteria were recruited from the antenatal clinics of Mae Sot Hospital, Tak Province, Thailand, (n = 8) and the Tropical Diseases Research Centre, Ndola, Zambia (n = 18). Patients were treated with four Malarone tablets (GlaxoSmithKline: each tablet contains 250 mg atovaquone and 100 mg proguanil) once daily for 3 consecutive days. Blood samples were taken for pharmacokinetic investigations of atovaquone, proguanil, and cycloguanil up to 288 h (day 14) after the last dose. Urine samples were collected for the evaluation of proguanil and cycloguanil 0-8, 8-16, 16-24 and 24-48 h after the last dose. Efficacy assessments included the clinical and parasitological evaluation of mothers and newborns. Adverse events were evaluated at each visit to the antenatal clinics., Results: Malarone appeared to be effective and well tolerated when used for the treatment of falciparum malaria in pregnant women. All patients showed prompt clinical improvement and the disappearance of parasitaemia after treatment. There were no serious adverse effects or unexpected adverse effects and no stillbirths or spontaneous abortions. The plasma concentration-time profiles of atovaquone and proguanil in most cases were best characterised by the two-compartment open model with zero-order input with/without absorption lag time and first-order elimination. There were no significant differences in any of the pharmacokinetic parameters of atovaquone, proguanil or cycloguanil between patients from Thailand and Zambia. For atovaquone, a Cmax of 1.33-8.33 microg/ml was reached at 2.0-9.3 h after the last dose on day 2. V/F, CL/F and t(1/2beta) were 6.9-39.5 l/kg, 83-384 ml/h/kg, and 57.8-130.8 h, respectively. The Cmax and t(max) values for proguanil versus cycloguanil were 383-918 versus 0-129 ng/ml and 3.3-8.6 versus 3-12 h, respectively. V/F, CL/F, and t(1/2beta) values for proguanil were 10.7-34.0 l/kg, 431-1,662 ml/h/kg and 11.2-30.3 h. The CL(R-CG), t(1/2z), (CG), proguanil/cycloguanil metabolic ratios, AUC ratios for proguanil to cycloguanil (AUC(PG/CG)) were 107.2-1,001 ml/h/kg, 5-95 ml/h/kg, 7.8-20.7 h, 5-57, and 4.7-20.2, respectively., Conclusion: The pharmacokinetics of atovaquone and cycloguanil appeared to be influenced by the pregnancy status, resulting in an decrease in the Cmax and AUC of approximately twofold.

Reduction of naphthoquinones by DT-diaphorase is often described as a detoxification reaction. This is true for some naphthoquinone derivatives, such as alkyl and di-alkyl naphthoquinones, but the situation with other substances, such as 2-hydroxy-1,4-naphthoquinone, is more complex. In the present study, the effect of several substances that are known to increase tissue activities of DT-diaphorase on the toxicity of 2-amino-1,4-naphthoquinone has been investigated. Like 2-hydroxy-1,4-naphthoquinone, the 2-amino-derivative was found to cause both haemolytic anaemia and renal tubular necrosis in rats. Again like 2-hydroxy-1,4-naphthoquinone, the severity of the haemolysis induced by the 2-amino derivative was increased in animals pre-treated with inducers of DT-diaphorase, but the degree of nephrotoxicity was decreased. With these substances, therefore, DT-diaphorase both activates and detoxifies the quinone, depending on the target organ. It is not possible to generalize with regard to the effects of modulation of tissue levels of DT-diaphorase on naphthoquinone toxicity in vivo, since this may change not only the severity of the toxic effects, but also the target organ specificity. In evaluating the possible therapeutic applications of such compounds, the possibility of toxic effects upon the blood and kidney must be borne in mind. In man, renal damage by compounds such as 2-hydroxy- and 2-amino-1,4-naphthoquinone may be a particular problem, because of the low level of DT-diaphorase in human liver.

NAD(P)H:quinone oxidoreductase (NQO1) is elevated in human pancreatic cancers. We hypothesized that beta-lapachone, a novel 1,2-naphthoquinone with potential antitumor activity in cancer cells expressing elevated levels of NQO1, would induce cytotoxicity in pancreatic cancer cells, wherein this two-electron reductase was recently found elevated. beta-lapachone decreased clonogenic cell survival, metabolic cell viability, and anchorage- independent growth in soft agar. The cytotoxic in vitro effects of beta-lapachone were inhibited with coadministration of dicumarol, a specific inhibitor of NQO1. In preestablished human pancreatic tumor xenografts in nude mice, beta-lapachone demonstrated greater tumor growth inhibition when given intratumorally compared to when complexed with cyclodextrin to increase its bioavailability. Due to the poor prognosis of patients with pancreatic cancer and the limited effectiveness of surgery, chemotherapy, and radiation therapy, treatment regimens based on sound, tumor-specific rationales are desperately need for this disease.

Acute therapy with pyrimethamine plus sulfadiazine is the treatment of choice for reactivated toxoplasmic encephalitis (TE). Acute therapy is followed by lifelong maintenance therapy (secondary prophylaxis) with the same drugs at lower dosages. The use of pyrimethamine plus sulfadiazine is hampered by severe side effects including allergic reactions and hematotoxicity. Alternative treatment regimens with pyrimethamine plus clindamycin or other antiparasitic drugs are less efficacious. Atovaquone nanosuspensions show excellent therapeutic effects for "acute" intravenous (i.v.) treatment of reactivated TE in a murine model. In the present study, the therapeutic efficacy of atovaquone for oral "maintenance" therapy was investigated. Mice with a targeted mutation in the interferon regulatory factor 8 gene were latently infected with Toxoplasma gondii, developed reactivated TE, and received acute i.v. therapy with atovaquone nanosuspensions. Mice were then treated orally with atovaquone suspension or other antiparasitic drugs to prevent relapse of TE. Maintenance therapy with atovaquone at daily doses of 50 or 100 mg/kg (body weight) protected mice against reactivated TE and death. This maintenance treatment was superior to standard therapy with pyrimethamine plus sulfadiazine. The latter combination was superior to the combination of pyrimethamine plus clindamycin. Inflammatory changes in the brain parenchyma and meninges, as well as parasite numbers, in the brains of mice confirmed the therapeutic efficacy of atovaquone for maintenance therapy. Atovaquone was detectable in sera, brains, livers, and lungs of infected mice by high-performance liquid chromatography and/or mass spectrometry. In conclusion, atovaquone appears to be superior to the standard maintenance therapy regimens in a murine model of reactivated TE. The therapeutic efficacy of atovaquone for maintenance therapy against TE should be further investigated in clinical trials.

The indolequinone compound EO9 has good pharmacodynamic properties in terms of bioreductive activation and selectivity for either NAD(P)H:quinone oxidoreductase-1 (NQO1)-rich aerobic or NQO1-deficient hypoxic cells. However, its pharmacokinetic properties are poor and this fact is believed to be a major reason for EO9's lack of clinical efficacy. The purpose of this study was to develop quinone-based bioreductive drugs that retained EO9's good properties, in terms of bioreductive activation, but have improved pharmacokinetic properties. Out of 11 naphthoquinone compounds evaluated, 2-aziridinyl-5-hydroxy-1,4-naphthoquinone (compound 2), 2,3-bis(aziridinyl)-5-hydroxy-1,4-naphthoquinone (compound 3), and 2-aziridinyl-6-hydroxymethyl-1,4-naphthoquinone (compound 11) were selected for further evaluation based on good substrate specificity for NQO1 and selectivity towards NQO1-rich cells in vitro. Compound 3 was of particular interest as it also demonstrated selectivity for NQO1-rich cells under hypoxic conditions. Compound 3 was not metabolised by murine whole blood in vitro (in contrast to compounds 2, 11 and EO9) and pharmacokinetic studies in non-tumour-bearing mice in vivo (at the maximum soluble dose of 60 mg kg(-1) administered intraperitoneally) demonstrated significant improvements in plasma half-life (16.2 min) and AUC values (22.5 microM h) compared to EO9 (T(1/2) = 1.8 min, AUC = 0.184 microM h). Compound 3 also demonstrated significant anti-tumour activity against H460 and HCT-116 human tumour xenografts in vivo, whereas EO9 was inactive against these tumours. In conclusion, compound 3 is a promising lead compound that may target both aerobic and hypoxic fractions of NQO1-rich tumours and further studies to elucidate its mechanism of action and improve solubility are warranted.

Malarone (atovaquone-proguanil) is an effective drug for the treatment and prophylaxis of multidrug-resistant falciparum malaria. However, first cases of resistance have been reported, which are associated with mutations at codon 268 of the parasite's cytochrome b gene. We report the first case of Malarone treatment failure from Central Africa.Drug concentration was well within curative range. Pre- and post-treatment Plasmodium falciparum isolates revealed codon 268 wild-type alleles, and no other mutations of the putative atovaquone-binding domain.These findings illustrate the spread of atovaquone-proguanil-resistance in Africa and question the usefulness of codon 268 as the only target for the surveillance of its emergence.

Microcapsules containing the pharmaceutical substance alkannin were prepared by the solvent evaporation method to enhance alkannin stability (reduce photo-oxidation, polymerization), to decrease its hydrophobicity and to control its release rate. The effect of various parameters, such as the type of polymeric matrix, the type of surfactant used for microcapsules preparation and the addition of Pistacia lentiscus resin in the core, on the characteristics of the produced microcapsules and the release rate of alkannin were investigated experimentally. Among the polymers tested for matrix, ethylcellulose of viscosity 46cp was the most successful, while ethylcellulose 10cp gave microcapsules with good morphological characteristics but high release rate. Beeswax resulted in flocculation and P. lentiscus resin with or without colophony as the matrix resulted in compact particles with no pores and much slower release, but did not allow alkannin to release easily from the matrix. Sodium dodecyl sulfate resulted in microcapsules with desirable morphological and physicochemical characteristics, while acacia and tragacanth gums were not indicated as surfactants in alkannin microencapsulation since they gave a high release rate and a great extent of particle size, respectively. The incorporation of Pistacia lentiscus resin in the capsule core increased loading and microencapsulation efficiency. Ethylcellulose of 46cp viscosity with sodium dodecyl sulfate as surfactant had the best characteristics studied for alkannin microencapsulation. Finally, the dissolution rate of alkannin from microcapsules was studied in a simulated intestinal and gastric environment and an external environment. Alkannin-containing microcapsules with improved properties can be used internally and externally as a new drug-delivery system.

Purpose: To explore the use of cyclodextrins (CD) to form inclusion complexes with beta-lapachone (beta-lap) to overcome solubility and bioavailability problems previously noted with this drug., Methods: Inclusion complexes between beta-lap and four cyclodextrins (alpha-, beta-, gamma-, and HPbeta-CD) in aqueous solution were investigated by phase solubility studies, fluorescence, and 1H-NMR spectroscopy. Biologic activity and bioavailability of beta-lap inclusion complexes were investigated by in vitro cytotoxicity studies with MCF-7 cells and by in vivo lethality studies with C57Blk/6 mice (18-20 g)., Results: Phase solubility studies showed that beta-lap solubility increased in a linear fashion as a function of alpha-, beta-, or HPbeta-CD concentrations but not gamma-CD. Maximum solubility of beta-lap was achieved at 16.0 mg/ml or 66.0 mM with HPbeta-CD. Fluorescence and 1H-NMR spectroscopy proved the formation of 1:1 inclusion complexes between beta-CD and HPbeta-CD with beta-lap. Cytotoxicity assays with MCF-7 cells showed similar biologic activities of beta-lap in beta-CD or HPbeta-CD inclusion complexes (TD50 = 2.1 microM). Animal studies in mice showed that the LD50 value of beta-lap in an HPbeta-CD inclusion complex is between 50 and 60 mg/kg., Conclusions: Complexation of beta-lap with HPbeta-CD offers a major improvement in drug solubility and bioavailability.

Objective: To determine the pharmacokinetic properties of atovaquone, proguanil, and the triazine metabolite cycloguanil in women with recrudescent multi-drug resistant falciparum malaria during the second and third trimesters of pregnancy treated by artesunate-atovaquone-proguanil., Methods: Serial plasma concentrations of atovaquone, proguanil and cycloguanil were measured in 24 women at baseline and after the final dose of the 3-day treatment with atovaquone (20 mg/kg/day) plus proguanil (8 mg/kg/day) plus artesunate (4 mg/kg/day) daily., Results: The triple combination was well tolerated and highly effective. The outcomes of pregnancy were all normal. Population mean (+/- SEM) oral clearance (Cl/F) estimates were 313+/-33 ml/h/kg and 1109+/-43 ml/h/kg, total apparent volume of distribution (Vd/F) 13.0+/-1.3 l/kg and 22.9+/-1.4 l/kg, and terminal elimination half-life; 29.1 h and 14.3 h, for atovaquone and proguanil, respectively. Using conventional and population pharmacokinetic analyses, Cl/F and Vd/F estimates for both drugs were approximately twice, and plasma concentrations less than half those reported previously in healthy subjects and patients with acute malaria., Conclusion: Artesunate-atovaquone-proguanil is a promising treatment for multi-drug resistant falciparum malaria during pregnancy, but the dose of atovaquone-proguanil may need to be increased.

Objective: To review the currently available information on atovaquone-proguanil for treatment and prophylaxis of malaria., Data Sources: A MEDLINE search was conducted from 1966 to February 2003 using key phrases Malarone, atovaquone, proguanil, and malaria. Further articles were identified from a manual search of the references of identified articles., Study Selection and Data Extraction: English-language studies with animal and human data evaluating preclinical pharmacology, human studies on pharmacokinetics, and clinical trials were evaluated. Relevant data were extracted from identified articles., Data Synthesis: Atovaquone-proguanil has been evaluated for treatment of acute, uncomplicated malaria caused by Plasmodium falciparum in 8 clinical trials. In these studies, treatment with atovaquone-proguanil led to a higher (87-100% vs. 72-88%) or equally effective (94-100% vs. 90-100%) cure rate than the comparator antimalarial agents. Atovaquone-proguanil has been evaluated for prophylaxis of malaria in 6 clinical trials. In the 4 placebo-controlled trials for semi-immune residents or nonimmune migrants, the prophylaxis success rates in the atovaquone-proguanil and placebo arms ranged from 98% to 100% and 48% to 82%, respectively. The prophylaxis with success rates were similar among the 2 arms when atovaquone-proguanil was compared with other antimalarial regimens in nonimmune travelers. Atovaquone-proguanil was well tolerated in these clinical trials., Conclusions: Atovaquone-proguanil is a safe and effective alternative to current recommended regimens for prophylaxis and treatment of malaria.

2-Hydroxy-1,4-naphthoquinone (HNQ; Lawsone; CAS 83-72-7) is the principal natural dye ingredient contained in the leaves of Henna (Lawsonia inermis). Published genotoxicity studies on HNQ suggested it was a weak bacterial mutagen for Salmonella typhimurium strain TA98 or was more clearly mutagenic for strain TA 2637, both in the presence of metabolic activation. HNQ was unable to induce sex-linked recessive lethal mutations in Drosophila melanogaster. However, a small increase in micronucleus frequency was reported in the bone marrow of mice at a single mid-range dose level, 24h after intraperitoneal injection. In view of the wide use of Henna hair dyes it was deemed necessary to conduct a thorough investigation, under Good Laboratory Practice conditions, of the genotoxicity of HNQ. HNQ was non-mutagenic in bacterial (Ames test) or mammalian (V79 hprt) assays. It was borderline positive in a mouse lymphoma tk mutation assay and a chromosome aberration test (CHO cells), results that may reflect a similar clastogenic mechanism. Negative in vivo genotoxicity results were noted in the rat hepatocyte in vivo/in vitro UDS test, in peripheral lymphocytes (chromosome aberrations) of rats receiving repeated oral doses of HNQ at the MTD for 28 days, and in mouse and hamster bone marrow chromosome aberration tests. However small, but statistically significant increases in the incidence of bone marrow micronuclei were observed in two out of five tests at 72 h after dosing, but not at 24 or 48 h. There was evidence of haematotoxicity at 72 h, which may have been enhanced by the vehicle (DMSO) used in the positive tests. As erythropoiesis and administration of haematotoxic agents are known to induce small increases in the frequency of bone marrow micronuclei, typically at delayed sampling times, the data suggest that the positive 72 h response produced by HNQ is consistent with stimulation of haematopoiesis subsequent to haematological toxicity of HNQ, and not due to a DNA-reactive mechanism. Overall, the weight of evidence suggests that Henna and HNQ pose no genotoxic risk to the consumer.

Published pharmacokinetic data indicate that after treatment of patients with therapeutic doses of atovaquone/proguanil hydrochloride (Malarone, GlaxoSmithKline Research Triangle Park, NC), the plasma half-lives of these drugs are 70h and 15h, respectively. However, using two biologic assays (mosquito transmission and in vitro asexual stage development), we demonstrate here that sera from volunteers treated with atovaquone/proguanil retained activity against Plasmodium falciparum up to 6 weeks after such treatment. This activity was due to atovaquone, as administration of this drug alone replicated the data obtained with the combination. Most notably, asexual stage development of an atovaquone-resistant strain (NGATV01) of P. falciparum was not inhibited by sera taken after atovaquone treatment. These data indicate that for atovaquone, biologic assays, though not quantitative, are more sensitive than the usual physicochemical assays. Also, persistence of atovaquone in plasma at low concentrations for long periods may increase the risk of resistant parasites arising.

The increasing prevalence of resistance to antimalarial drugs reduces options for malaria prophylaxis. Atovaquone/proguanil (Malarone; GlaxoSmithKline) has been >95% effective in preventing Plasmodium falciparum malaria in lifelong residents of areas of holoendemicity, but data from persons without clinical immunity or who are at risk for Plasmodium vivax malaria have not been described. We conducted a randomized, double-blinded study involving 297 people from areas of nonendemicity in Indonesia who migrated to Papua (where malaria is endemic) < or =26 months before the study period. Subjects received prophylaxis with 1 Malarone tablet (250 mg of atovaquone and 100 mg of proguanil hydrochloride; n=148) or placebo (n=149) per day for 20 weeks. Hematologic and clinical chemistry values did not change significantly. The protective efficacy of atovaquone/proguanil was 84% (95% confidence interval [CI], 44%-95%) for P. vivax malaria, 96% (95% CI, 72%-99%) for P. falciparum malaria, and 93% (95% CI, 77%-98%) overall. Atovaquone/proguanil was well tolerated, safe, and effective for the prevention of drug-resistant P. vivax and P. falciparum malaria in individuals without prior malaria exposure who migrated to Papua, Indonesia.

Naphthalene is an important industrial chemical, which has recently been shown to cause tumors of the respiratory tract in rodents. It is thought that one or more reactive metabolites of naphthalene, namely, naphthalene-1,2-oxide (NPO), 1,2-naphthoquinone (1,2-NPQ), and 1,4-naphthoquinone (1,4-NPQ) contribute to the tumorigenicity of this chemical. These electrophiles are all capable of covalent binding to macromolecules including DNA and proteins. The stability of cysteinyl adducts of NPO, 1,2-NPQ, and 1,4-NPQ were investigated in both hemoglobin (Hb) and albumin (Alb) of male F344 rats following a single administration of 2 different doses (400 or 800 mg naphthalene per kg body weight). To assess the stability of Alb adducts, we compared the rates of NPO-Alb turnover (half-life of approximately 2 days) and 1,2-NPQ-Alb (half-life of approximately 1 day) to the normal turnover rate of Alb in the rat (half-life = 2.5-3 days). Based on the rapid turnover of these adducts relative to Alb itself, we concluded that they were unstable. However, the stability of Alb adducts was not affected by the dose of naphthalene administered (400 or 800 mg/kg). In contrast, NPO-Hb adducts were relatively stable (rate constant of adduct instability