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Protein arginine methyltransferases (PRMTs) are important therapeutic targets, playing a crucial role in the regulation of many cellular processes and being linked to many diseases. Yet, there is still much to be understood regarding their functions and the biological pathways in which they are involved, as well as on the structural requirements that could drive the development of selective modulators of PRMT activity. Here we report a deconstruction-reconstruction approach that, starting from a series of type I PRMT inhibitors previously identified by us, allowed for the identification of potent and selective inhibitors of PRMT4, which regardless of the low cell permeability show an evident reduction of arginine methylation levels in MCF7 cells and a marked reduction of proliferation. We also report crystal structures with various PRMTs supporting the observed specificity and selectivity.

The bromodomain and extra-terminal (BET) family of proteins includes BRD2, BRD3, BRD4, and the testis-specific protein, BRDT, each containing two N-terminal tandem bromodomain (BRD) modules. Potent and selective inhibitors targeting the two bromodomains are required to elucidate their biological role(s), with potential clinical applications. In this study, we designed and synthesized a series of benzimidazole-6-sulfonamides starting from the azobenzene compounds MS436 (7 a) and MS611 (7 b) that exhibited preference for the first (BD1) over the second (BD2) BRD of BET family members. The most-promising compound (9 a) showed good binding potency and improved metabolic stability and selectivity towards BD1 with respect to the parent compounds.

An updated outlook on protein lysine methyltransferase-disclosed modulators is presented, reporting their potency, mechanism of action and eventual use in clinical and preclinical studies.

Inhibition of Carbonic Anhydrases (CAs) has been clinically exploited for many decades for a variety of therapeutic applications. Within a research project aimed at developing novel classes of CA inhibitors (CAIs) with a proper selectivity for certain isoforms, a series of derivatives featuring the 2-substituted-benzimidazole-6-sulfonamide scaffold, conceived as frozen analogs of Schiff bases and secondary amines previously reported in the literature as CAIs, were investigated. Enzyme inhibition assays on physiologically relevant human CA I, II, IX and XII isoforms revealed a number of potent CAIs, showing promising selectivity profiles towards the transmembrane tumor-associated CA IX and XII enzymes. Computational studies were attained to clarify the structural determinants behind the activities and selectivity profiles of the novel inhibitors., Graphical Abstract

Over the past years, growing interest toward post-translational modifications (PTMs) of histones and nonhistone proteins has prompted academia and industrial research groups to develop different approaches to better understand the link between PTMs and pathological states. Selective recognition of PTMs is carried out by reader modules, which mediate the biological readout of epigenetic mechanisms. Progress in medicinal chemistry and chemical biology has contributed to corroborate the role of reader domains in chromatin-binding proteins as potential therapeutic targets. Here, we review the state-of-the-art of the most important small molecules developed to date, with a particular attention on contemporary chemical biology approaches, including photoaffinity probes, cyclic peptides, bifunctional inhibitors, and PROTAC degraders.

Since the discovery of compound BIX01294 over 10 years ago, only a very limited number of nonquinazoline inhibitors of H3K9-specific methyltransferases G9a and G9a-like protein (GLP) have been reported. Herein, we report the identification of a novel chemotype for G9a/GLP inhibitors, based on the underinvestigated 2-alkyl-5-amino- and 2-aryl-5-amino-substituted 3 H-benzo[ e][1,4]diazepine scaffold. Our research efforts resulted in the identification 12a (EML741), which not only maintained the high in vitro and cellular potency of its quinazoline counterpart, but also displayed improved inhibitory potency against DNA methyltransferase 1, improved selectivity against other methyltransferases, low cell toxicity, and improved apparent permeability values in both parallel artificial membrane permeability assay (PAMPA) and blood-brain barrier-specific PAMPA, and therefore might potentially be a better candidate for animal studies. Finally, the co-crystal structure of GLP in complex with 12a provides the basis for the further development of benzodiazepine-based G9a/GLP inhibitors. Since the discovery of compound BIX01294 over 10 years ago, only a very limited number of nonquinazoline inhibitors of H3K9-specific methyltransferases G9a and G9a-like protein (GLP) have been reported. Herein, we report the identification of a novel chemotype for G9a/GLP inhibitors, based on the underinvestigated 2-alkyl-5-amino- and 2-aryl-5-amino-substituted 3H-benzo[e][1,4]diazepine scaffold. Our research efforts resulted in the identification 12a (EML741), which not only maintained the high in vitro and cellular potency of its quinazoline counterpart, but also displayed improved inhibitory potency against DNA methyltransferase 1, improved selectivity against other methyltransferases, low cell toxicity, and improved apparent permeability values in both parallel artificial membrane permeability assay (PAMPA) and blood-brain barrier-specific PAMPA, and therefore might potentially be a better candidate for animal studies. Finally, the co-crystal structure of GLP in complex with 12a provides the basis for the further development of benzodiazepine-based G9a/GLP inhibitors.

Buprenorphine transdermal delivery system (BTDS) applied once every 7 days is indicated for the management of pain that is severe enough to require daily, around-the-clock, long-term opioid treatment and for which alternative treatment options are inadequate. The 7-day flux of buprenorphine from BTDS to systemic circulation was investigated in a phase 1, 2-period crossover study with 3 randomized groups of healthy subjects receiving BTDS containing buprenorphine 5, 10, or 20 mg for 7 days preceded or followed by intravenous buprenorphine infusion (25 μg/h for 24 hours). Residual and absolute bioavailability methods were used to estimate 7-day flux of buprenorphine. Following BTDS administration, mean area under the curve of buprenorphine increased proportionally (12.6, 24.3, and 51.1 ng/[mL · h]), maximum mean plasma concentration rose with increasing dose (176, 191, and 471 pg/mL), and absolute bioavailability was 14% to 16%. Mean residual amount of buprenorphine in the BTDS after 7-day application was 4.50, 8.57, and 17.1 mg. Flux of buprenorphine was approximately 5, 10, and 20 μg/h for BTDS containing 5, 10, and 20 mg buprenorphine, respectively. BTDS was safe and well tolerated following a single 7-day application in healthy subjects. The results of this study demonstrated dose-dependent flux of buprenorphine delivered via transdermal system.

Purpose A single-entity, once-daily, extended-release formulation of hydrocodone bitartrate (HYD) has been developed for the management of moderate to severe chronic pain. Hydrocodone undergoes cytochrome P-450 (CYP)-mediated metabolism involving the CYP3A4 and CYP2D6 isozymes. CYP3A4 yields norhydrocodone, a major inactive metabolite, whereas CYP2D6 yields hydromorphone, a minor active metabolite. This study examined the influence of the coadministration of paroxetine, a strong selective CYP2D6 inhibitor, on the pharmacokinetic properties of hydrocodone (and hydromorphone) in healthy adults. Methods In this randomized, double-blind, 2-period, 2-treatment crossover study, 24 healthy subjects received paroxetine 20 mg or placebo once daily for 12 days and an HYD 20-mg tablet on day 10 of each period. Findings Hydrocodone mean C max and t ½ and median T max values were similar with paroxetine or placebo coadministration (16.8 vs 15.9 ng/mL, 8.5 vs 8.4 hours, and 18.0 vs 18.0 hours, respectively), as were mean AUC 0–t and AUC 0–∞ values (342.9 vs 325.3 ng · h/mL and 346.3 vs 328.5 ng · h/mL). The 90% CIs of the geometric mean ratios of the hydrocodone AUC and C max values were fully within the predetermined range of 80% to 125%, suggesting that there was no effect of multiple doses of paroxetine on systemic exposure to hydrocodone. Mean hydromorphone AUC 0–t and C max values were decreased with paroxetine versus placebo (0.64 vs 3.8 ng · h/mL and 0.06 vs 0.19 ng/mL), whereas T max values remained similar (18.0 vs 16.1 hours, respectively). The mean hydromorphone AUC 0–∞ value could not be calculated. Both regimens were well tolerated; after HYD administration, the numbers of adverse events were similar between the 2 treatment regimens, and all adverse events were mild. Implications In this study, the coadministration of single-dose HYD with paroxetine at steady state did not alter systemic exposure to hydrocodone, suggesting that HYD can be coadministered with CYP2D6 inhibitors at therapeutic doses, without dosage modification.

Context Transdermal formulations of buprenorphine offer controlled delivery of buprenorphine for sustained analgesic efficacy with reduced adverse events (AEs) compared with the other modes of administration. A buprenorphine transdermal system (BTDS) delivering 5, 10, or 20 mcg/hour for seven days is now marketed in the U.S. as Butrans ® (Lohmann Therapie-System AG, Andernach Germany), a Schedule III single-entity opioid analgesic indicated for the management of moderate and chronic pain in patients requiring continuous around-the-clock analgesia for an extended period. Objectives This was a randomized open-label study in healthy subjects to characterize the steady-state buprenorphine pharmacokinetics after the delivery of three consecutive seven-day BTDS applications. Methods Thirty-seven subjects were randomized to receive three consecutive BTDS 10 mcg/hour (BTDS 10) patches applied to the deltoid or upper back for seven days each. Blood samples for buprenorphine concentration measurements were taken. Safety was assessed using recorded AEs, clinical laboratory test results, vital signs, pulse oximetry, physical examinations, and electrocardiograms. Patch adhesion assessments were taken. Results Analysis of C min demonstrated that steady state was reached during the first BTDS 10 application. No significant difference in C min was observed across the three applications. Total and peak plasma buprenorphine exposures were similar after each of the seven-day administrations of BTDS. Conclusion Three consecutive once-weekly applications of BTDS 10 provided consistent and sustained delivery of buprenorphine. Steady-state plasma concentrations were reached within 48 hours of the first application of BTDS 10. Patch adhesion analysis confirmed the appropriateness of the seven-day application period. Overall, BTDS 10 was safe and well tolerated.

Background and Objective: Buprenorphine is extensively metabolized by cytochrome P450 (CYP) 3A4. This study evaluated the effect of ketoconazole, a CYP3A4 inhibitor, on the metabolism of buprenorphine following the administration of a buprenorphine transdermal system 10μg/hour (BTDS 10). Methods: This single-centre study enrolled 20 healthy subjects who had demonstrated ketoconazole-mediated CYP3A4 inhibition via an erythromycin breath test. Subjects were randomized into a placebo-controlled, two-treatment, two-period crossover study. Subjects participated in a 7- to 14-day screening period, two baseline evaluations (day 0 [period 1] and day 16 [period 2]), two 12-day treatment periods (periods 1 and 2) separated by a 4-day washout period, and a study completion visit. Subjects received one BTDS 10 for 7 days per treatment period, administered concomitantly with either ketoconazole 200 mg twice daily or matching placebo. The main outcome measures were the ratios of geometric means for area under the plasma drug concentration versus time curve (AUC) from time zero to time of last measurable concentration (AUClast), AUC from time zero to infinity (AUC∞), and maximum plasma drug concentration (Cmax). Results: The ratio of geometric means (BTDS 10 with ketoconazole/BTDS 10 with placebo) was 99.4 (90% confidence interval [CI] 87.2, 113.3) for AUClast and 97.8 (90% CI 87.7, 109.1) for Cmax. The ratio of geometric means for AUC∞ was 86.7 (90% CI 70.7, 106.2). The plasma concentrations of the metabolites norbuprenorphine and norbuprenorphine-3β-glucuronide were slightly elevated following ketoconazole administration. BTDS 10 with ketoconazole was well tolerated and no apparent safety concerns were noted. Conclusion: The lack of a clinically significant CYP3A4 interaction with ketoconazole following transdermal delivery of buprenorphine is consistent with the parenteral administration of a high clearance drug bypassing exposure to gut wall and hepatic CYP3A4 first-pass effects. Metabolism of buprenorphine during therapy with BTDS is also not expected to be affected by co-administration of other CYP3A4 inhibitors.

Buprenorphine transdermal delivery system (BTDS) applied once every 7 days is indicated for the management of pain that is severe enough to require daily, around-the-clock, long-term opioid treatment and for which alternative treatment options are inadequate. The 7-day flux of buprenorphine from BTDS to systemic circulation was investigated in a phase 1, 2-period crossover study with 3 randomized groups of healthy subjects receiving BTDS containing buprenorphine 5, 10, or 20 mg for 7 days preceded or followed by intravenous buprenorphine infusion (25 μg/h for 24 hours). Residual and absolute bioavailability methods were used to estimate 7-day flux of buprenorphine. Following BTDS administration, mean area under the curve of buprenorphine increased proportionally (12.6, 24.3, and 51.1 ng/[mL · h]), maximum mean plasma concentration rose with increasing dose (176, 191, and 471 pg/mL), and absolute bioavailability was 14% to 16%. Mean residual amount of buprenorphine in the BTDS after 7-day application was 4.50, 8.57, and 17.1 mg. Flux of buprenorphine was approximately 5, 10, and 20 μg/h for BTDS containing 5, 10, and 20 mg buprenorphine, respectively. BTDS was safe and well tolerated following a single 7-day application in healthy subjects. The results of this study demonstrated dose-dependent flux of buprenorphine delivered via transdermal system.

Hydromorphone hydrochloride extended release (HHER) is a multiparticulate melt-extrusion pellet capsule formulation administered q24h. Study 1 investigated the bioavailability of 24-mg HHER fed, as well as 24-mg and 12-mgHHER and 8-mg hydromorphone hydrochloride immediate-release (HHIR) tablets fasting. No clinically significant food effect was observed on hydromorphone C m a x orAUCfor the 24-mg HHER, and dose proportionality (AUC) was demonstrated between 12- and 24-mg HHER. Study 2 demonstrated dose strength proportionality for 3×12-mg HHER versus 1 x 32-mg HHER. Study 3 evaluated 12-mg HHER q24h versus 3-mg HHIR q6h at steady state. HHER produced relatively constant steady-state concentrations over 24 hours. HHER and HHIR were equivalent for AUC s s . C s s m a x was 26% lower for HHER than HHIR, C s s m i n was 43% higher for HHER, and peak-to-trough fluctuation was 126% for HHER versus 328% for HHIR, which are ideal attributes of a once-daily oral extended- release dosage form. HHER administration resulted in fewer adverse events than HHIR in study 3.

Incremental lines in dental cementum of museum specimens of 11 free-ranging great apes were compared to the respective structures in 5 captive specimens of known age-at-death, and with many known life-history parameters. While the dental cementum of the free-ranging apes was regularly structured into alternating dark and light bands, 4 out of 5 captive animals showed marked irregularities in terms of hypomineralized bands which could all be dated to the year 1963. Cementum preservation was insufficient in the fifth specimen and did not permit such a differentiation. All 4 captive apes had been kept in a zoo located in the northern hemisphere, where 1963 was characterized by an extremely cold winter. Since cold stress is a calcium-consuming process, the lack of available calcium in newly forming cementum could be responsible for the observed hypomineralization. The appositional growth characteristics of dental cementum serve as a record for such life-history events.

The pharmacokinetics and bioavailability of nitroglycerin (GTN) and its metabolites, 1,2-glyceryl dinitrate (1,2-GDN) and 1,3-glyceryl dinitrate (1,3-GDN), were compared after a single 14-hour application of Transderm-Nitro (Ciba-Geigy, Summit, NJ), Nitrodisc (GD Searle, Chicago, IL), and Nitro-Dur II (Key Pharmaceuticals, Kenilworth, NJ) systems to 18 healthy male subjects on 3 separate occasions. A 14-hour intravenous infusion of 15N-labeled GTN was given simultaneously to correct for changes in systemic clearance during the application of each system. Plasma concentrations of 15N-labeled GTN, unlabeled GTN, and their corresponding dinitrate metabolites were measured using a gas chromatography/mass spectrometry method. Results showed that the plasma concentration profiles of nitroglycerin and its metabolites for the three systems were similar during and after system removal. Mean (SD) total amounts (AUCp x CLiv) of GTN transdermally available after adjustment for 15N-labeled GTN clearance were 5.3 (2.1), 5.3 (2.0), and 5.4 (2.6) mg for Transderm-Nitro, Nitrodisc, and Nitro-Dur II, respectively. Mean (SD) AUC values for 1,2-GDN were 44.6 (15.8), 44.3 (16.1), and 42.8 (19.3) ng.h/mL for the 3 systems. Corresponding AUC values for 1,3-GDN were 9.3 (2.9), 9.7 (2.9), and 8.7 (3.0) ng.h/mL. Statistical analysis of the log-transformed data based on 90% conventional confidence interval showed that all 3 systems delivered equivalent amounts of nitroglycerin into the systemic circulation. The AUC ratios for 1,3-GDN to GTN, but not 1,2-GDN to GTN, were statistically different for the intravenous and transdermal routes during all 3 system applications, indicating that the formation and metabolism of 1,3-GDN was dependent on route of administration.

Objectives. A once-daily, extended-release hydrocodone bitartrate tablet with abuse-deterrent properties (Hysingla ER® [HYD]) is available for the treatment of chronic pain in appropriate patients. This study evaluated the intranasal abuse potential and pharmacokinetics of HYD coarse and fine particles vs hydrocodone powder or placebo. Design. Single-center, double-blind, positive- and placebo-controlled, randomized, four-treatment crossover study. Subjects. Healthy adult, nondependent, recreational opioid users with a history of intranasal abuse. Methods. During four treatment periods, subjects (N = 31) received hydrocodone powder 60 mg, HYD coarse particles 60 mg, HYD fine particles 60 mg, or placebo, with five-to-seven-day washouts between treatments. Measures over 36 hours postdose included drug-liking and willingness to take drug again, assessed using visual analog scales (VASs), pupillometry, intranasal irritation, and pharmacokinetics. Results. Insufflation of both HYD coarse and fine particles led to lower “At this Moment” Drug Liking VAS peak values compared with hydrocodone powder, but higher values compared with placebo (P

Purpose The purpose of this study was to evaluate the pharmacokinetics (PK) and 24-hour analgesic effectiveness of once-daily, single-entity, extended-release hydrocodone (HYD) with abuse-deterrent properties. Methods Four studies were included. Three open-label PK studies had the following designs: single-dose, 5-treatment, 4-period, crossover, dose-proportionality study; HYD 120 mg for 5 days (steady-state study 1); 2-treatment, 2-period, multiple-dose crossover study assessing the relative bioavailability of HYD 30 mg and hydrocodone 7.5 mg/ibuprofen 200 mg administered every 6 hours (steady-state study 2). A long-term, open-label study assessed the safety and effectiveness of HYD 20 to 120 mg in patients during a 52-week maintenance period. Findings Thirty-one, 25, and 22 healthy subjects completed the dose-proportionality study, steady-state study 1, and steady-state study 2, respectively, while 410 patients with moderate to severe chronic nonmalignant and non-neuropathic pain completed the long-term effectiveness study. Mean systemic exposure and peak plasma concentration were dose proportional after administration of single doses of HYD 20 to 120 mg. Pharmacokinetic profiles were comparable at day 1 and day 5 after administration of HYD 120 mg once daily. Once-daily HYD 30 mg was associated with lower-fluctuating plasma hydrocodone concentrations compared with immediate-release hydrocodone 7.5 mg/ibuprofen 200 mg administered every 6 hours. In the long-term study, pain control was consistent over the 24-hour dosing interval. Implications Once-daily HYD exhibits linear, dose-proportional PK properties and is associated with a lower variability in plasma hydrocodone concentrations when compared with an immediate-release hydrocodone combination product. Notably, analgesia provided by HYD is sustained during the 24-hour dosing interval. ClinicalTrials.gov identifier: NCT01400139 (Study 4).