Related Experiment Video

Updated: Aug 14, 2026

Evaluation of Drug Sorption to PVC- and Non-PVC-based Tubes in Administration Sets Using a Pump
06:08

Evaluation of Drug Sorption to PVC- and Non-PVC-based Tubes in Administration Sets Using a Pump

Published on: March 11, 2017

Multiple-dose halazepam kinetics

M Chung, J M Hilbert, R P Gural

    Clinical Pharmacology and Therapeutics
    |June 1, 1984
    PubMed

    Halazepam is a benzodiazepine used in the management of anxiety disorders or short-term relief of anxiety. Our study was undertaken to evaluate its steady-state kinetics and those of its major active plasma metabolite N- desalkylhalazepam . Eleven healthy men aged 19 to 35 yr were given oral, 40-mg halazepam tablets every 8 hr for 14 days. Plasma samples were analyzed by gas chromatography to determine levels of halazepam and N- desalkylhalazepam . Halazepam kinetics can best be described by a two-compartment open model with first-order absorption kinetics. The elimination phase t1/2s of halazepam and N- desalkylhalazepam were 34.7 and 57.9 hr. Steady-state levels were predictable from kinetic data and were reached by the third day for halazepam and by the eleventh day for N- desalkylhalazepam .

    More Related Videos

    Microdialysis of Excitatory Amino Acids During EEG Recordings in Freely Moving Rats08:47

    Microdialysis of Excitatory Amino Acids During EEG Recordings in Freely Moving Rats

    Published on: November 8, 2018

    Behavioral Characterization of Pentylenetetrazole-induced Seizures: Moving Beyond the Racine Scale07:35

    Behavioral Characterization of Pentylenetetrazole-induced Seizures: Moving Beyond the Racine Scale

    Published on: July 8, 2025

    Related Concept Videos

    Nonlinear Pharmacokinetics: Overview01:19

    Nonlinear Pharmacokinetics: Overview

    Nonlinear or dose-dependent pharmacokinetics is a phenomenon that occurs when the pharmacokinetic parameters of certain drugs deviate from linear pharmacokinetics at higher doses. These drugs do not follow the expected first-order kinetics, where the rate of drug elimination is directly proportional to the drug concentration. Instead, they exhibit a nonlinear relationship, which can be attributed to several factors.
    Nonlinearity can arise due to the saturation of plasma protein-binding or...
    Nonlinear Pharmacokinetics: Dependence of Elimination Half-Life and Dose Clearance01:23

    Nonlinear Pharmacokinetics: Dependence of Elimination Half-Life and Dose Clearance

    The elimination half-life and drug clearance of drugs following nonlinear kinetics can vary with dosage. The Michaelis-Menten parameters and drug concentration influence these factors. As the dose increases, the elimination half-life tends to lengthen, resulting in a reduction in clearance and a disproportionately larger area under the curve. The total clearance can be derived from the Michaelis-Menten equation for drugs following a one-compartment model.
    A study on guinea pigs examined the...
    Dosage Regimens: Partial Pharmacokinetic Parameters01:01

    Dosage Regimens: Partial Pharmacokinetic Parameters

    It is not uncommon for complete drug pharmacokinetic profiles to remain elusive in pharmacokinetics. This necessitates certain educated assumptions by pharmacokineticists to determine appropriate dosage regimens without comprehensive pharmacokinetic data from animal or human studies. One prevalent assumption is setting the bioavailability factor, denoted as F, to 1 or 100%. This assumption caters to the scenario where a drug doesn't achieve full systemic absorption, resulting in the patient...
    Pharmacokinetic–Pharmacodynamic Relationship: Dose to Pharmacological Effect01:28

    Pharmacokinetic–Pharmacodynamic Relationship: Dose to Pharmacological Effect

    A drug’s dosage and pharmacokinetic properties determine how quickly it acts, how intense its effects are, and how long it lasts. Higher doses increase drug concentration at receptor sites, producing a hyperbolic curve when pharmacologic response is plotted against drug dose. Converting this scale to a log-linear format results in a sigmoidal curve, better representing dose–response relationships.For drugs following a one-compartment model, the pharmacologic response is directly proportional to...
    Pharmacokinetic–Pharmacodynamic Relationship: Duration of Dose-Effect Relationship01:14

    Pharmacokinetic–Pharmacodynamic Relationship: Duration of Dose-Effect Relationship

    For drugs producing a quantal response, onset occurs when plasma concentration reaches a minimum effective level (Cmin). The drug's action duration depends on how long the plasma concentration remains above Cmin.Two primary factors influence this duration: dose size and the rate of drug removal from the action site. Both depend on the drug's redistribution to poorly perfused tissues and elimination processes. A larger dose promotes rapid onset and prolongs the effect's duration.Consider a...
    Pharmacokinetic–Pharmacodynamic Relationship: Intensity of Dose-Effect Relationship01:23

    Pharmacokinetic–Pharmacodynamic Relationship: Intensity of Dose-Effect Relationship

    Pharmacodynamics explores the relationship between drug concentration and its effect. In a quantal response drug, the duration of action better correlates with drug concentration, while for graded effect drugs, the intensity of response is more relevant. This intensity depends on the dose, drug removal rate, and the region of the concentration–response curve.The concentration–response curve can be divided into three regions. Region 3 (80–100% maximum response) demonstrates that even as drug...