Metabolism and disposition of zamicastat in rats.

The metabolism and disposition of zamicastat, a reversible dopamine β-hydroxylase (DβH) inhibitor, developed for treatment of Pulmonary Arterial Hypertension (PAH), were investigated in rats after oral and intravenous administration of [C]-zamicastat.Zamicastat was rapidly absorbed and widely distributed to peripheral tissues, with total radioactivity almost completely recovered 168 h post-dose. Its main route of excretion was via faeces, whilst urine and expired air had minor roles.

Third-Generation Solid Dispersion Through Lyophilization Enhanced Oral Bioavailability of Resveratrol.

Resveratrol (RES) is a biopharmaceutical classification system (BCS) class II compound with low solubility and high permeability. Several strategies have been explored to overcome the low bioavailability of RES, making the formation of solid dispersions (SDs) one of the most promising. This study aimed at the development of a RES third-generation SD prepared by lyophilization as a strategy to improve RES solubility, dissolution, and oral bioavailability.

Voltage-clamp evidence of GABA receptor subunit-specific effects: pharmacodynamic fingerprint of chlornordiazepam, the major active metabolite of mexazolam, as compared to alprazolam, bromazepam, and zolpidem.

Background: Anxiolytic benzodiazepines, due to their clinical effectiveness, are one of the most prescribed drugs worldwide, despite being associated with sedative effects and impaired psychomotor and cognitive performance. Not every GABA receptor functions in the same manner. Those containing α1 subunits are associated with sleep regulation and have a greater effect on the sedative-hypnotic benzodiazepines, whereas those containing α2 and/or α3 subunits are associated with anxiety phenomena and have a greater effect on the anxiolytic benzodiazepines.

Absorption, metabolism and excretion of opicapone in human healthy volunteers.

Aims: The absorption, metabolism and excretion of opicapone (2,5-dichloro-3-(5-[3,4-dihydroxy-5-nitrophenyl]-1,2,4-oxadiazol-3-yl)-4,6-dimethylpyridine 1-oxide), a selective catechol-O-methyltransferase inhibitor, were investigated.

Methods: Plasma, urine and faeces were collected from healthy male subjects following a single oral dose of 100 mg [ C]-opicapone. The mass balance of [ C]-opicapone and metabolic profile were evaluated.

Metabolism and disposition of opicapone in the rat and metabolic enzymes phenotyping.

Opicapone (2,5-dichloro-3-(5-(3,4-dihydroxy-5-nitrophenyl)-1,2,4-oxadiazol-3-yl)-4,6-dimethylpyridine 1-oxide) is a selective catechol-O-methyltransferase inhibitor that has been granted marketing authorization in Europe, Japan, and United States. The present work describes the metabolism and disposition of opicapone in the rat obtained in support to its development and regulatory filling. Plasma levels and elimination of total radioactivity were determined after oral and intravenous administration of [ C]-opicapone.

Opicapone enhances the reversal of MPTP-induced Parkinson-like syndrome by levodopa in cynomolgus monkeys.

Opicapone is a third generation nitrocatechol catechol-O-methyltransferase inhibitor that has received regional market approval for use as adjunctive therapy to levodopa in Parkinson's disease patients with motor fluctuations. This study evaluated the effects of opicapone as adjunct to levodopa in reversing a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induced Parkinson's-like syndrome in cynomolgus monkeys in during opicapone preclinical development program. A Parkinson's-like syndrome was induced in cynomolgus monkeys by daily administrations of MPTP.

Inhibition of catechol-O-methyltransferase in the cynomolgus monkey by opicapone after acute and repeated administration.

Introduction: The aim of the study was to clarify the dose response for inhibition of catechol-O-methyltransferase (COMT) by opicapone, a third generation COMT inhibitor, after acute and repeated administration to the cynomolgus monkey with pharmacokinetic evaluation at the higher dose.

Methods: Three cynomolgus monkeys were used in the study. In the first experiment, COMT inhibition was evaluated over 24 h after the first and at 24 h after the last of 14 daily oral administrations of vehicle, 1, 10 and 100 mg/kg opicapone using a crossover design.

Discovery of a Potent, Long-Acting, and CNS-Active Inhibitor (BIA 10-2474) of Fatty Acid Amide Hydrolase.

Fatty acid amide hydrolase (FAAH) can be targeted for the treatment of pain associated with various medical conditions. Herein we report the design and synthesis of a novel series of heterocyclic-N-carboxamide FAAH inhibitors that have a good alignment of potency, metabolic stability and selectivity for FAAH over monoacylglycerol lipase (MAGL) and carboxylesterases (CEs). Lead optimization efforts carried out with benzotriazolyl- and imidazolyl-N-carboxamide series led to the discovery of clinical candidate 8 l (3-(1-(cyclohexyl(methyl)carbamoyl)-1H-imidazol-4-yl)pyridine 1-oxide; BIA 10-2474) as a potent and long-acting inhibitor of FAAH.

A single- and multiple-dose study to investigate the pharmacokinetics and pharmacodynamics of opicapone, a novel COMT inhibitor, in rat.

Opicapone is a novel catechol-O-methyltransferase (COMT) inhibitor that emerged to fulfil the need of a safer and more efficacious COMT inhibitor. The present study was carried out in order to assess and compare the pharmacokinetics and pharmacodynamics (COMT inhibition) of opicapone after single and multiple oral administrations (30 mg/kg) to Wistar rats. For this purpose, at predefined time points up to 72 h post-dosing, blood, liver and kidneys were collected and, then, the concentrations of opicapone and its active metabolite (BIA 9-1079) were determined in plasma and in liver and kidney tissues, as well as the erythrocyte, liver and kidney COMT activity.

Effect of opicapone multiple-dose regimens on levodopa pharmacokinetics.

Aims: To compare the levodopa/carbidopa (LC) and levodopa/benserazide (LB) pharmacokinetic profiles following repeated doses of opicapone (OPC) administered apart from levodopa.

Methods: Two randomized, double blind, sex-balanced, placebo-controlled studies in four groups of 12 or 18 healthy subjects each. In each group, enrolled subjects received a once-daily morning (5, 15 and 30 mg) or evening (5, 15 and 50 mg) administration of OPC or placebo for up to 28 days.

Carbamazepine aggravates absence seizures in two dedicated mouse models.

Background: The aim of this study was to evaluate the effect of carbamazepine (CBZ) upon chemically induced absence seizures and in a genetic absence seizures model in the mouse.

Methods: The γ-butyrolactone (GBL)-induced acute absence seizures and the stargazer spontaneous absence seizures mice models were used to characterize the aggravation of absence seizures induced by oral CBZ treatment. The effect of CBZ upon GABA inward-currents in Ltk cells expressing human recombinant α1β2γ2, α2β2γ2, α3β2γ2 and α5β2γ2 GABAA receptors was evaluated by means of patch clamp.

An artificial neural network for membrane-bound catechol-O-methyltransferase biosynthesis with Pichia pastoris methanol-induced cultures.

Background: Membrane proteins are important drug targets in many human diseases and gathering structural information regarding these proteins encourages the pharmaceutical industry to develop new molecules using structure-based drug design studies. Specifically, membrane-bound catechol-O-methyltransferase (MBCOMT) is an integral membrane protein that catalyzes the methylation of catechol substrates and has been linked to several diseases such as Parkinson's disease and Schizophrenia. Thereby, improvements in the clinical outcome of the therapy to these diseases may come from structure-based drug design where reaching MBCOMT samples in milligram quantities are crucial for acquiring structural information regarding this target protein.

Eslicarbazepine acetate for the treatment of focal epilepsy: an update on its proposed mechanisms of action.

Eslicarbazepine acetate (ESL) is a once daily antiepileptic drug (AED) approved by the European Medicines Agency (EMA), the Food and Drug Administration (FDA) and Health Canada as an adjunctive therapy in adults with partial-onset seizures (POS). In humans and in relevant animal laboratory species, ESL undergoes extensive first pass hydrolysis to its major active metabolite eslicarbazepine that represents ∼95% of circulating active moieties. ESL and eslicarbazepine showed anticonvulsant activity in animal models.

Role of P-glycoprotein and permeability upon the brain distribution and pharmacodynamics of etamicastat: a comparison with nepicastat.

1. This study explores the impact of permeability and P-glycoprotein (P-gp) efflux, upon brain exposure to etamicastat, a new dopamine-β-hydroxylase (DBH) inhibitor and consequently brain levels of catecholamines. 2.

Characterization of the interaction of the novel antihypertensive etamicastat with human dopamine-β-hydroxylase: comparison with nepicastat.

The interaction of etamicastat, a novel peripherally acting dopamine-β-hydroxylase (DBH) inhibitor, with the enzyme was studied using a classical kinetic approach and the pharmacodynamics effect of the compound upon administration to rats was also evaluated. SK-N-SH cell homogenates convert tyramine into octopamine with a Km value of 9 mM, and a Vmax of 1747 nmol/mg protein/h. The K(m) value for ascorbate was 3 mM.

Targeting pharmacoresistant epilepsy and epileptogenesis with a dual-purpose antiepileptic drug.

In human epilepsy, pharmacoresistance to antiepileptic drug therapy is a major problem affecting a substantial fraction of patients. Many of the currently available antiepileptic drugs target voltage-gated sodium channels, leading to a rate-dependent suppression of neuronal discharge. A loss of use-dependent block has emerged as a potential cellular mechanism of pharmacoresistance for anticonvulsants acting on voltage-gated sodium channels.

Blood pressure-decreasing effect of etamicastat alone and in combination with antihypertensive drugs in the spontaneously hypertensive rat.

Hyperactivation of the sympathetic nervous system has an important role in the development and progression of arterial hypertension. This study evaluated the efficacy of etamicastat, a dopamine-β-hydroxylase (DβH) inhibitor, in controlling high blood pressure in the spontaneously hypertensive rat (SHR), either alone or in combination with other classes of antihypertensives. SHRs were administered with etamicastat by gavage, and its pharmacodynamic and pharmacokinetic properties were evaluated.

Eslicarbazepine and the enhancement of slow inactivation of voltage-gated sodium channels: a comparison with carbamazepine, oxcarbazepine and lacosamide.

This study aimed at evaluating the effects of eslicarbazepine, carbamazepine (CBZ), oxcarbazepine (OXC) and lacosamide (LCM) on the fast and slow inactivated states of voltage-gated sodium channels (VGSC). The anti-epileptiform activity was evaluated in mouse isolated hippocampal slices. The anticonvulsant effects were evaluated in MES and the 6-Hz psychomotor tests.

Etamicastat, a new dopamine-ß-hydroxylase inhibitor, pharmacodynamics and metabolism in rat.

Despite the importance of sympathetic nervous system in pathophysiological mechanisms of cardiac heart failure and essential hypertension, therapy specifically targeting the sympathetic nervous system is currently underutilized. Etamicastat is a novel dopamine-ß-hydroxylase (DBH) inhibitor that is oxidized into BIA 5-965 and deaminated followed by oxidation to BIA 5-998, which represents 13% of total etamicastat and quantified metabolites. However, the primary metabolic pathway of etamicastat in rats was found to be the N-acetylation (BIA 5-961), which represents 44% of total etamicastat and quantified metabolites.

N-acetylation of etamicastat, a reversible dopamine-β-hydroxylase inhibitor.

Etamicastat [(R)-5-(2-aminoethyl)-1-(6,8-difluorochroman-3-yl)-1H-imidazole-2(3H)-thione hydrochloride] is a reversible dopamine-β-hydroxylase inhibitor that decreases norepinephrine levels in sympathetically innervated tissues. After in vivo administration, N-acetylation of etamicastat was found to be a main metabolic pathway. The purpose of the current study was to characterize the N-acetylation of etamicastat by N-acetyltransferases (NAT1 and NAT2) and evaluate potential species differences in etamicastat N-acetylation using a sensitive and specific liquid chromatography-mass spectrometry assay.

Performance of hydrophobic interaction ligands for human membrane-bound catechol-O-methyltransferase purification.

Despite of membrane catechol-O-methyltransferase (MBCOMT, EC 2.1.1.

Opicapone: a short lived and very long acting novel catechol-O-methyltransferase inhibitor following multiple dose administration in healthy subjects.

Aims: The aim of this study was to assess the tolerability, pharmacokinetics and inhibitory effect on erythrocyte soluble catechol-O-methyltransferase (S-COMT) activity following repeated doses of opicapone.

Methods: This randomized, placebo-controlled, double-blind study enrolled healthy male subjects who received either once daily placebo or opicapone 5, 10, 20 or 30 mg for 8 days.

Results: Opicapone was well tolerated.

Pharmacokinetics, pharmacodynamics and tolerability of opicapone, a novel catechol-O-methyltransferase inhibitor, in healthy subjects: prediction of slow enzyme-inhibitor complex dissociation of a short-living and very long-acting inhibitor.

Background And Objectives: Opicapone is a novel catechol-O-methyltransferase (COMT) inhibitor. The purpose of this study was to evaluate the tolerability, pharmacokinetics (including the effect of food) and pharmacodynamics (effect on COMT activity) following single oral doses of opicapone in young healthy male volunteers.

Methods: Single rising oral doses of opicapone (10, 25, 50, 100, 200, 400, 800 and 1,200 mg) were administered to eight groups of eight subjects per group (two subjects randomized to placebo and six subjects to opicapone), under a double-blind, randomized, placebo-controlled design.

Computation of the binding affinities of catechol-O-methyltransferase inhibitors: multisubstate relative free energy calculations.

Alchemical free energy simulations are amongst the most accurate techniques for the computation of the free energy changes associated with noncovalent protein-ligand interactions. A procedure is presented to estimate the relative binding free energies of several ligands to the same protein target where multiple, low-energy configurational substates might coexist, as opposed to one unique structure. The contributions of all individual substates were estimated, explicitly, with the free energy perturbation method, and combined in a rigorous fashion to compute the overall relative binding free energies and dissociation constants.

Hepatic UDP-glucuronosyltransferase is responsible for eslicarbazepine glucuronidation.

Eslicarbazepine acetate (ESL) is a once-daily novel antiepileptic drug approved in Europe for use as adjunctive therapy for refractory partial-onset seizures with or without secondary generalization. Metabolism of ESL consists primarily of hydrolysis to eslicarbazepine, which is then subject to glucuronidation followed by renal excretion. In this study, we have identified that human liver microsomes (HLM) enriched with uridine 5'-diphosphoglucuronic acid give origin to a single Escherichia coli β-glucuronidase-sensitive eslicarbazepine glucuronide (most likely the O-glucuronide).