Comparative single-dose kinetics of oxazolam, prazepam, and clorazepate: three precursors of desmethyldiazepam

Synthesis of 1,3,5-Triazepines and Benzo[f][1,3,5]triazepines and Their Biological Activity: Recent Advances and New Approaches

This review article discusses the recent progress in synthesizing seven-membered ring 1,3,5-triazepine and benzo[f][1,3,5]triazepine derivatives. These derivatives can be either unsaturated, saturated, fused, or separated. This review covers strategies and procedures developed over the past two decades, including cyclo-condensation, cyclization, methylation, chlorination, alkylation, addition, cross-coupling, ring expansions, and ring-closing metathesis. This review discusses the synthesis of 1,3,5-triazepine derivatives using nucleophilic or electrophilic substitution reactions with various reagents such as o-phenylenediamine, 2-aminobenzamide, isothiocyanates, pyrazoles, thiazoles, oxadiazoles, oxadiazepines, and hydrazonoyl chloride. This article systematically presents new approaches and techniques for preparing these compounds. It also highlights the biological importance of benzo[f][1,3,5]triazepine derivatives, which have been used as drugs for treating nervous system diseases. This review aims to provide researchers with the necessary information to create and develop new derivatives of these compounds as quickly as possible.

Searching glycolate oxidase inhibitors based on QSAR, molecular docking, and molecular dynamic simulation approaches

Primary hyperoxaluria type 1 (PHT1) treatment is mainly focused on inhibiting the enzyme glycolate oxidase, which plays a pivotal role in the production of glyoxylate, which undergoes oxidation to produce oxalate. When the renal secretion capacity exceeds, calcium oxalate forms stones that accumulate in the kidneys. In this respect, detailed QSAR analysis, molecular docking, and dynamics simulations of a series of inhibitors containing glycolic, glyoxylic, and salicylic acid groups have been performed employing different regression machine learning techniques. Three robust models with less than 9 descriptors-based on a tenfold cross (Q² _CV) and external (Q² _EXT) validation-were found i.e., MLR1 (Q² _CV = 0.893, Q² _EXT = 0.897), RF1 (Q² _CV = 0.889, Q² _EXT = 0.907), and IBK1 (Q² _CV = 0.891, Q² _EXT = 0.907). An ensemble model was built by averaging the predicted pIC₅₀ of the three models, obtaining a Q² _EXT = 0.933. Physicochemical properties such as charge, electronegativity, hardness, softness, van der Waals volume, and polarizability were considered as attributes to build the models. To get more insight into the potential biological activity of the compouds studied herein, docking and dynamic analysis were carried out, finding the hydrophobic and polar residues show important interactions with the ligands. A screening of the DrugBank database V.5.1.7 was performed, leading to the proposal of seven commercial drugs within the applicability domain of the models, that can be suggested as possible PHT1 treatment.

Real-world evidence on the use of benzodiazepine receptor agonists and the risk of venous thromboembolism

BACKGROUND

Venous thromboembolism (VTE) is a life-threatening disease, and some studies reported that benzodiazepine receptor agonist (BZRA) use could increase the risk of VTE, but this association lacks population-based evidence.

OBJECTIVES

To investigate the association between BZRA use and the risk of VTE.

PATIENTS/METHODS

A nested case-control study analyzing Taiwan's claims database was conducted of patients with at least one new BZRA prescription on record from January 1, 2002, to December 31, 2012. We included new users who did not have any BZRA prescriptions in the preceding 2 years and identified cases with VTE and disease risk score matched control subjects. We used a logistic regression model to investigate the association between BZRA exposure and the risk of VTE. The exposure duration, dose, and classes of BZRAs were comprehensively evaluated.

RESULTS

We identified 2800 VTE cases and 2800 matched controls. Current BZRA prescription (≤90 days) was associated with VTE occurrence (adjusted odds ratio [aOR]: 1.83; 95% confidence interval [CI], 1.62-2.06). The point estimates of benzodiazepine hypnotics (aOR: 2.00; 95% CI, 1.45-2.76) had a marginally higher risk of VTE than nonbenzodiazepine hypnotics (aOR: 1.39; 95% CI, 1.07-1.81). The VTE risk was increased with combination BZRA use, number of BZRA used, and a higher dose of BZRA. On examination of individual BZRA, the risk of VTE was higher with flunitrazepam use (aOR: 2.99; 95% CI, 1.43-6.28) than other BZRAs.

CONCLUSIONS

This study presents that current BZRA use may increase the risk of VTE. Also, benzodiazepine hypnotics, especially flunitrazepam, have a higher risk of VTE.

Slow Accumulation and Elimination of Diazepam and Its Active Metabolite With Extended Treatment in the Elderly

Age-related changes in disposition of diazepam and its principal active metabolite, desmethyldiazepam (DMDZ), during and after extended dosage with diazepam were studied in healthy volunteers. Eight elderly subjects (ages 61-78 years) and 7 young subjects (21-33 years) received 2.5 mg of diazepam twice daily for 15 days. Predose (trough) concentrations of diazepam and DMDZ were measured during the 15 days of dosing, and in the postdosage washout period. Kinetic properties were determined by nonlinear regression using a sequential drug-to-metabolite pharmacokinetic model. Steady-state plasma concentrations of diazepam and DMDZ were 30% to 35% higher in elderly subjects compared to young volunteers, and steady-state clearances correspondingly lower, though differences did not reach significance. Large and significant differences were found between young and elderly groups in mean half-life of diazepam (31 vs 86 hours; P < .005) and DMDZ (40 vs 80 hours; P < .02). Half-life values from the multiple-dose study were closely correlated with values from previous single-dose studies of diazepam (R² = 0.85) and DMDZ (R² = 0.94) in the same subjects. With extended dosing of diazepam in the elderly, slow accumulation and delayed washout of diazepam and DMDZ is probable. After discontinuation, withdrawal or rebound effects are reduced in likelihood, but delayed recovery from sedative effects is possible due to slow elimination of active compounds. Safe treatment of elderly patients with diazepam is supported by understanding of age-related changes in pharmacologic and pharmacokinetic properties.

Microsomal prediction ofin vivoclearance and associated interindividual variability of six benzodiazepines in humans

The intrinsic clearances (CLint) of midazolam, triazolam, diazepam, nordiazepam, flunitrazepam and alprazolam were determined from two liver banks (n=21) by formation kinetics of ten metabolites. A literature-collated database of in vivo CLint values (811 subjects) was used to assess predictions and variability. The in vivo clearance of six benzodiazepines was generally underpredicted by in vitro data and the degree of bias was in agreement with a database of structurally diverse compounds (n=37). The variability observed for in vitro clearances (11--19--fold for midazolam, diazepam and nordiazepam in liver bank 1; 101--269--fold for triazolam, flunitrazepam and alprazolam in liver bank 2) exceeded the in vivo variability for the same compounds (4--59 and 10--29, respectively). This mismatch may contribute to the bias in microsomal predictions and it highlights the need for careful selection of representative livers for human liver banks.

A method for screening for various sedative-hypnotics in serum by liquid chromatography/single quadrupole mass spectrometry

A screening method for the detection of sedative-hypnotics in serum is described. The target drugs, which include practically all the sedative-hypnotics distributed in Japan, consisted of 5 barbiturates, 30 benzodiazepine-related drugs and 11 other sedative-hypnotics (i.e., apronalide, bromisovalum, chloral hydrate, triclofos, chlorpromazine, promethazine, diphenhydramine, hydroxyzine, zopiclone, zolpidem and tandospirone). Thirty-nine analytes, selected in terms of the pharmacokinetics of the target drugs, in human serum were screened using a combination of mixed-mode solid-phase extraction and liquid chromatography/electrospray-ionization single-quadrupole mass spectrometry. The detection limits (non-basic analytes, 1-50 ng/ml; basic analytes, 0.1-5 ng/ml) were sufficient to permit the screening of a single therapeutic administration of a target drug.

Clinical pharmacokinetics of anxiolytics and hypnotics in the elderly. Therapeutic considerations (Part II)

Part I of this article, which appeared in the previous issue of the Journal, discussed the scope of and scientific basis for special pharmacokinetic studies of anxiolytic and hypnotic drugs in the elderly, and examined the methodology and results of such studies and the prediction of pharmacokinetic changes. In Part II the authors continue their review, focusing on age-related pharmacodynamic changes in the effects of these drugs, the attempts to correlate pharmacokinetic with pharmacodynamic findings, and the clinical applications of these data.

Pharmacokinetics and metabolism of halazepam in naive and dependent dogs

The pharmacokinetic profiles of halazepam (HL) and its metabolites, desmethyldiazepam (DMDZ), oxazepam (OX), 3-hydroxyhalazepam (OH-HL), and conjugates of oxazepam (OX-CONJ) and 3-hydroxyhalazepam (OH-HL-CONJ) were studied in 4 naive dogs following single intravenous (2 mg/kg) and oral (112.5 mg/kg) administrations of HL and in 5 dependent dogs chronically dosed with HL (450 mg/kg/day q.i.d.). HL is rapidly metabolized to DMDZ as the principal metabolite but appreciable levels of HL, OX and OH-HL were measured in plasma and the brain tissue. High levels of conjugated metabolites were measured in plasma. The steady-state plasma concentrations of HL and its unconjugated metabolites can be predicted from the single dose study. Halazepam does not serve as a simple prodrug for DMDZ in producing physical dependence in dogs.

Physiological modeling of drug and metabolite: disposition of oxazepam and oxazepam glucuronides in the recirculating perfused mouse liver preparation

The disposition of tracer doses of 3H-oxazepam was studied in the recirculating perfused mouse liver preparation. 3H-Oxazepam was biotransformed primarily to the diastereomeric 3H-oxazepam glucuronides, which either effluxed into the circulation or underwent biliary excretion. Three additional, unknown metabolites constituted a small fraction (5-10%) of the total radioactivity recovered in bile (7% of dose); no other metabolite was detected in perfusate. A physiologically based model, comprising the reservoir, liver blood and tissue, and bile, was fitted to reservoir concentrations of 3H-oxazepam and 3H-oxazepam glucuronides, and the cumulative amount excreted into bile. The model allowed for consideration of elimination pathways other than glucuronidation and the presence of a transport barrier for the oxazepam glucuronides across the hepatocyte membrane. The fitted results suggest a slight barrier existing for the transport of metabolites across the sinusoidal membrane, inasmuch as the transmembrane clearance was comparable to liver blood flow rate. Upon further comparison of estimates of formation, biliary, and transmembrane clearances for the oxazepam glucuronides, the rate-limiting step in the overall (biliary) clearance appears to be a poor capacity for biliary excretion. The influence of the cumulative volume loss that a recirculating perfused organ system incurs upon repeated sampling was discussed, and a compartmental method of correcting the observed concentrations of drug and generated metabolite was presented.

Primary, secondary, and tertiary metabolite kinetics

Because of the propensity of nascently formed metabolites towards sequential metabolism within formation organs, theoretical and experimental treatments that achieve mass conservation must recognize the various sources contributing to primary, secondary, and tertiary metabolite formation. A simple one-compartment open model, with first-order conditions and the liver as the only organ of drug disappearance and metabolite formation, was used to illustrate the metabolism of a drug to its primary, secondary, and tertiary metabolites, encompassing the cascading effects of sequential metabolism. The concentration-time profiles of the drug and metabolites were examined for two routes of drug administration, oral and intravenous. Formation of the primary metabolite from drug in the gut lumen, with or without further absorption, and metabolite formation arising from first-pass metabolism of the drug and the primary metabolite during oral absorption were considered. Mass balance equations, incorporating modifications of the various absorption and conversion rate constants, were integrated to provide the explicit solutions. Simulations, with and without consideration of the sources of metabolite formation other than from its immediate precursor, were used to illustrate the expected differences in circulating metabolite concentrations. However, a simple relationship between the area under the curve of any metabolite, M, or [AUC (m)], its clearance [CL(m)], and route of drug administration was found. The drug dose, route, fraction absorbed into the portal circulation, Fabs, fraction available of drug from the liver, F, availabilities of the metabolites F(m) from formation organs, and CL(m) are determinants of the AUC(m)'s. After iv drug dosing, the area of any intermediary metabolites is determined by the iv drug dose divided by the (CL(m)/F(m] of that metabolite. When a terminal metabolite is not metabolized, its area under the curve becomes the iv dose of drug divided by the clearance of the terminal metabolite since the available fraction for this metabolite is unity. Similarly, after oral drug administration, when loss of drug in the gut lumen does not contribute to the appearance of metabolites systematically, the general solution for AUC(m) is the product of Fabs and oral drug dose divided by [CL(m)/F(m)]. A comparison of the area ratios of any metabolite after po and iv drug dosing, therefore, furnishes Fabs. When this fraction is divided into the overall systemic availability or Fsys, the drug availability from the first-pass organs, F, may be found.(ABSTRACT TRUNCATED AT 400 WORDS)

Desmethyldiazepam pharmacokinetics: studies following intravenous and oral desmethyldiazepam, oral clorazepate, and intravenous diazepam

After single 10-mg intravenous (IV) doses of desmethyldiazepam (DMDZ) to 12 healthy human volunteers, (mean age, 62 years) blood samples were obtained over the next 14 or more days. Mean kinetic variables were volume of distribution (Vd), 90 liters; elimination half-life (t1/2), 93 hours; and clearance, 12.3 mL/min. Vd was significantly correlated with body weight (r = .73, P less than .01) and with percent ideal body weight (r = .91, P less than .001). Eleven of the same subjects also received 5- to 15-mg doses of IV diazepam (DZ). Mean kinetic variables were Vd, 180 liters; t1/2, 83 hours; and clearance, 28 mL/min. Clearances of DZ and DMDZ were significantly correlated (r = .73, P less than .02). Based on area analysis, the extent of conversion of DZ to systemic DMDZ averaged 53%. After oral administration of DMDZ in tablet form (10 mg), or of clorazepate dipotassium in capsule form (15 mg), systemic availability of DMDZ from each of the oral dosage forms was not significantly different from 100%.

Influence of propranolol coadministration or cigarette smoking on the kinetics of desmethyldiazepam following intravenous clorazepate

The influence of propranolol coadministration or of cigarette smoking on the kinetics of desmethyldiazepam following a single 20-mg intravenous dose of clorazepate dipotassium was evaluated in healthy volunteers. In Study One, intravenous clorazepate was given once in the control condition, and again during coadministration of propranolol, 80 mg twice daily. Compliance with the prescribed propranolol regimen was verified by measurement of serum propranolol concentrations (mean, 37 ng/ml). In control vs propranolol treatment conditions, there was no significant difference in desmethyldiazepam volume of distribution (1.27 vs 1.23 liters/kg) or in free fraction in serum (1.83 vs 1.80% unbound). There was a small although statistically significant prolongation of desmethyldiazepam half-life (55 vs 61 h, P less than 0.05) and reduction in clearance (0.281 vs 0.247 ml/min/kg, P less than 0.02) attributable to propranolol. In Study Two, desmethyldiazepam kinetics were compared in eight cigarette smokers (mean, 19 cigarettes/day) and in 11 nonsmoking controls matched for age, sex, and body weight. There was no significant difference between controls and cigarette smokers in desmethyldiazepam volume of distribution (1.29 vs 1.34 liters/kg), elimination half-life (55 vs 59 h), clearance (0.284 vs 0.276 ml/min/kg), or free fraction in serum (1.96 vs 1.92% unbound). Thus, propranolol slightly although significantly impairs the clearance of desmethyldiazepam and prolongs its half-life. Cigarette smoking has no apparent influence on desmethyldiazepam kinetics.

Hypnotics. Their place in therapeutics

Sleep disturbance has become a subject of serious study only over the past few years, but even so there is already an increasing awareness of the nature of insomnia and a greater understanding of the role which hypnotics should play in clinical medicine. An hypnotic may be used to shorten sleep onset when there is difficulty in falling asleep, to reduce nocturnal wakefulness, or to provide an anxiolytic effect during the next day when insomnia is accompanied by a marked element of anxiety. The purpose of an hypnotic is to meet one or more of these clinical problems; to ensure that the patient is given the most useful medication, consideration must be given to duration of activity. This depends on the absorption, distribution and elimination characteristics of the drug. It is now appreciated that the most appropriate use of hypnotics is in the individual with insomnia of recent origin. An hypnotic with the most relevant pharmacokinetic profile should be used for the shortest period of time and then only as required, while low doses will ensure freedom from adverse effects. The place of hypnotics in chronic insomnia remains less certain. Their careful use may well be of benefit, though it must be part of a well defined clinical strategy. Assessment of the patient is essential to identify any specific conditions which would impair sleep.