Diazepam and metabolites

High Pressure Liquid Chromatography. In blood, plasma or urine diazepam and metabolites, sensitivity 50 ng/ml in blood or plasma, 200 ng/ml in urine, UV detection—S. Cotier et al, J. Chromat., 1981, 222 Biomed. Appl., 11, 95-106. In plasma diazepam and desmethyldiazepam, comparison with a gas... 

Rapid Gas Chromatographic Method for the Determination of Diazepam and Metabolites in Body Fluids J. Chromatogr. 90(2) 325-329 (1974) CA 81 130733z... 

Cordero R, Paterson S (2007) Simultaneous quantification of opiates, amphetamines, cocaine and metabolites and diazepam and metabolite in a single hair sample using GC-MS. J Chromatogr B 850 423—431... 

For plasma and blood experiments, LC effluent was directed to waste for the first 1 min. Conventional blood analysis by drawing 1 mL samples from the saphenous catheter was used to validate SPME results. These samples were subjected to PPT with acetonitrile and the supernatant from centrifugation was analyzed. The SPME probes were also evaluated for pharmacokinetic analysis of diazepam and its metabolites, oxazepam and nordiazepam. Good correlation was obtained for conventional blood drawn from saphenous and cephalic sites of the animals, as shown in Figure 1.48. Although the analytical parameters for the automated study need improvement, the authors cite the study as a first demonstration of SPME technology for in vivo analysis. 

This section will illustrate the MIP technique for sample preparation by presenting examples of diazepam and its metabolites in hair samples.177 An anti-diazepam molecularly imprinted polymer... 

Diazepam and its nordiazepam, oxazepam, and temazepam metabolites are well retained by the MIP, while they are much less retained on NIP, also exhibiting large RSD. Other benzodiazepines of similar structures (Figure 1.50) were well retained on the MIP, showing that this template can be used for the general class of benzodiazepines. Two benzodiazepines studied, chlordiazepoxide and flunitrazepam, were poorly retained, indicating poor fit of these structures into the templated MIP. 

The relative contribution of the active metabolites of the benzodiazepines to the overall therapeutic effect of the parent compound will depend on the concentration of the metabolite formed, its agonist potency at central benzodiazepine receptors and its lipophilicity. For example, after the chronic administration of diazepam, desmethyldiazepam accumulates in the brain. As this metabolite has potency at the benzodiazepine receptors equal to diazepam, the metabolite probably plays an important part in the overall action of diazepam. In the case of clobazam, however, even though the active metabolite desmethylclobazam is present in higher concentrations than the parent compound after chronic administration, it has a lower potency than clobazam and therefore is of less importance than the parent compound with regard to the anxiolytic effect. 

Diazepam, oxazepam, and N-desmethyldiazepam have been determined under isocratic conditions (342) a somewhat more sensitive assay for diazepam and N-methyldiazepam has been reported (545). The closely related compounds, chlordiazepoxide and its N-demethyl metabolite, have also been determined (344). Analysis of the antidepressant amitriptyline, its metabolites and related drugs have been carried out using a four-component solvent (345, 346) and also aqueous acetonitrile (547). 

Eight BDZs among the most frequently encountered in forensic toxicology (clonazepam, desal-kylflurazepam, diazepam, flunitrazepam, lorazepam, midazolam, nordiazepam and oxazepam) were determined in whole blood after solvent extraction with butyl chloride and fast isocratic separation using a C18 (100 x 4.6 mm x 5 (tm) column [61]. The mobile phase was composed of phosphate buffer (35mM, pH 2.1) and acetonitrile (70 30, v/v) and the flow rate was 2mL/min. Within less than 4 min of analysis time, the analytes could be successfully determined starting from therapeutic concentrations. Using HPLC coupled with APCI-MS-MS, Rivera et al. [62] set up a method for the detection of 18 BDZ and metabolites after butyl chloride extraction at alkaline pH in 0.5mL... 

Cimetidine slows the metabolism of BZs. This slowing causes clinically significant increases in cognitive impairment when coadministerd with midazolam (Chouinard et ah, 1999). Cimetidine increases the levels of diazepam and its metabolite, but no pharmacodynamic effects have been demonstrated (Greenblatt et ah, 1984). 

The rates of oral absorption of sedative-hypnotics differ depending on a number of factors, including lipophilicity. For example, the absorption of triazolam is extremely rapid, and that of diazepam and the active metabolite of clorazepate is more rapid than other commonly used benzodiazepines. Clorazepate, a prodrug, is converted to its active form, desmethyldiazepam (nordiazepam), by acid hydrolysis in the stomach. Most of the barbiturates and other older sedative-hypnotics, as well as the newer hypnotics (eszopiclone, zaleplon, zolpidem), are absorbed rapidly into the blood following oral administration. 

The stability of diazepam and its metabolites (oxazepam, temazepam, and demeth-yldiazepam) when present in liver of treated bulls has been studied (108). Following boiling in water for 1 h, the oxazepam metabolite was the most unstable of the compounds studied, being degraded to an extent of approximately 50%. The parent drug and the other metabolites were more stable they were all present, after treatment, at levels corresponding to 79-89% of the initial concentrations. 

Polarographic methods have been extremely useful for the determination of the urinary excretion of the 1,4-benzodiazepines. An assay that employs selective solvent extraction and acid hydrolysis of diazepam and its major metabolites, iV-desmethyldiazepam and oxazepam, to their respective benzophe-nones has been employed to measure the urinary excretion of diazepam [183]. A pulse polarographic assay has been reported that will measure the urinary excretion of bromazepam following a single 12-mg dose [184]. The assay employs selective extraction of bromazepam and the 2-amino-5-bromobenzoyl-pyridine metabolite from the deconjugated metabolites, 3-hydroxybromazepam and 2-amino-3-hydroxy-5-bromobenzoylpyridine, into separate diethyl ether fractions. The residues of the respective extracts are dissolved in phosphate buffer (pH 5.4) and analyzed by pulse polarography, which yields two distinct... 

The determination of diazepam in plasma with detection limits of 0.03-0.2 fjLg/mh by cathode ray [189] and pulse polarography [174,190] has been described. The first reported pulse assay [174] differs from the other polarographic assays [189,190] in that a more polar solvent is employed to ensure quantitative extraction, followed by TLC separation and determination of diazepam and its major blood metabolite, N-desmethyldiazepam, to ensure specificity. 

Most muscle relaxants are absorbed fairly easily from the gastrointestinal tract, and the oral route is the most frequent method of drug administration. In cases of severe spasms, certain drugs such as methocarbamol and orphenadrine can be injected intramuscularly or intravenously to permit a more rapid effect. Likewise, diazepam and dantrolene can be injected to treat spasticity if the situation warrants a faster onset. As discussed earlier, continuous intrathecal baclofen administration may be used in certain patients with severe spasticity, and local injection of botulinum toxin is a possible strategy for treating focal dystonias and spasticity. Metabolism of muscle relaxants is usually accomplished by hepatic microsomal enzymes and the metabolite or intact drug is excreted through the kidneys. 

The pharmacokinetic properties of the benzodiazepines in part determine their clinical use. In general, the drugs are well absorbed, widely distributed, and extensively metabolized, with many active metabolites. The rate of distribution of benzodiazepines within the body is different from that of other antiseizure drugs. Diazepam and lorazepam in particular are rapidly and extensively distributed to the tissues, with volumes of distribution between 1 L/kg and 3 L/kg. The onset of action is very rapid. Total body clearances of the parent drug and its metabolites are low, corresponding to half-lives of 20-40 hours. 

Patients with hepatic insufficiency may not tolerate the drug at usual doses, however, because of increased area under the concentration curve of both parent drugs and metabolites. This may necessitate a dose reduction to 7.5 mg/kg every 12 hours or 5 mg/kg every 8 hours in some patients. Quinupristin and dalfopristin are not metabolized by cytochrome P450 enzymes but significantly inhibit CYP 3 A4, which metabolizes warfarin, diazepam, astemizole, terfenadine, cisapride, nonnucleo- side reverse transcriptase inhibitors, and cyclosporine, among others. Dosage reduction of cyclosporine may be necessary. 

The short-term effects are mainly those of sedation but following longer-term use accumulation may occur, particularly in the case of drugs like diazepam and chlordiazepoxide that have long half-lives due to their active metabolites. After long-term administration (weeks to months) tolerance develops. While most patients rapidly become tolerant to the sedative side effects of these drugs, some patients, particularly the elderly, experience excessive sedation, poor memory and concentration, motor incoordination and muscle weakness. In extreme cases in the elderly, an acute confusional... 

A 54-year-old man took 2 g of laboratory-grade diazepam and was treated with activated charcoal, diuresis, and flumazenil infusion (32). He wakened, but had drowsiness, dysarthria, diplopia, and dizziness for 9 days. Blood concentrations of diazepam and its main metabolite, TV-desmcthyldiazcpam, remained high for over 4 weeks. 

N-(l-naphthyl)ethylenediamine solution Chlordiazepoxide, oxazepam, and the metabolites of diazepam and medazepam are hydrolysed to 2-amino-5-chlorobenzophenone, which forms a violet dye with the reagents. The test does not distinguish, therefore, between these drugs. The test will detect benzodiazepines in urine at therapeutic concentrations but it is not specific. Any compound that yields an aryl amino group on hydrolysis, e.g. phenylbutazone, will respond to the test. 

Diazepam is a metabolite of ketazolam and medazepam. Therapeutic Concentration. In plasma, usually in the range 0.1 to 2.5 pg/ml. After discontinuation of chronic therapy, concentrations of desmethyldiazepam may be substantially higher than diazepam and both unchanged drug and metabolite are still detectable 7 days after cessation of dosing. 

Following a single oral dose of 30 mg of C-labelled ketazolam, peak plasma concentrations of about 0.004 pg/ml of ketazolam, 0.017 pg/ml of diazepam, and 0.127 ig/ml of A -demethylated metabolites were attained in 2, 10, and 14 hours respectively (F. S. Ebertsjun. etal.. Pharmacologist, 1977,19,165). 

The antianxiety effects of chlordiazepoxide (165) were described in 1960 and this compound was followed by diazepam (135). These two drugs have captured 75% of the market for sedatives in the USA. Other benzodiazepines used as antianxiety agents include oxazepam (166 R = H), a metabolite of diazepam that is better tolerated, lorazepam (166 R = Cl) and potassium clorazepate (167). Prazepam is the iV-cyclopropylmethyl analogue of diazepam. The benzodiazepines have other therapeutic applications, many being used for inducing sleep, diazepam and nitrazepam are anticonvulsants and flurazepam (168) is both an antianxiety agent and a potent hypnotic. Thieno- and pyrazolo-1,4-diazepinones isosteric with diazepam have similar pharmacological properties (B-81 Ml 10604). 

Hydroxybenzodiazepines represent active metabolites of many clinically useful benzodiazepines (e.g., diazepam), and consequently a large number of 3-substituted derivatives have been prepared and evaluated as anxiolytics in their own right. These compounds often show comparable potency to that of the parent benzodiazepines, but have a dramatically different metabolic profile. In hu-... 

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