Metabolites of demoxepam, a chlordiazepoxide metabolite, in man

Metabolic profile of oxazepam and related benzodiazepines: clinical and forensic aspects

Anxiolytic drugs, namely benzodiazepines, are the most commonly used psychoactive substances since anxiety disorders are prevalent mental disorders particularly in the Western world. Oxazepam is a short-acting benzodiazepine and one of the most frequently prescribed anxiolytic drugs. It is also the active metabolite of a wide range of other benzodiazepines, such as diazepam, ketazolam, temazepam, chlordiazepoxide, demoxazepam, halazepam, medazepam, prazepam, pinazepam, and chlorazepate. Therefore, relevant clinical and forensic outocomes may arise, namely those related to interference in driving performance. It is clinically available as a racemic formulation, with S-enantiomer being more active than R-enantiomer. In humans, it is mainly polimorphically metabolized by glucuronide conjugation at the 3-carbon hydroxyl group, yielding stable diastereomeric glucuronides (R- and S-oxazepam glucuronide). Relevant metabolic and stereoselective interspecies differences have been reported. In this work, the pharmacokinetics of oxazepam with particular focus on metabolic pathways is fully reviewed. Moreover, the metabolic profile of other prescribed benzodiazepines that produce oxazepam as a metabolite is also discussed. It is aimed that knowing the metabolism of oxazepam and related benzodiazepines may lead to the development of new analytical strategies for its early detection and help in further toxicological and clinical interpretations.

Biopharmacological data and high-performance liquid chromatographic analysis of 1,4-benzodiazepines in biological fluids: A review

A review with 123 references on the analysis of 1,4-benzodiazepines in biological samples using HPLC is presented. Some important physico-chemical and biopharmacological data for the development of analytical methods are collected. Different methods of sample pretreatment, chromatographic conditions and detection systems are discussed.

Chromatography of benzodiazepines

An overview of methods for the determination of benzodiazepines in biological media, based on the application of chromatographic techniques, is presented. A general discussion of the techniques in terms of stability, selectivity, validation, standardization, detection and sensitivity is given. No single technique can be claimed as the method of choice for benzodiazepines. Gas chromatography with electron-capture detection has some strong claims and shows generally good sensitivity and reproducibility. High-performance liquid chromatographic equipment is readily available in most laboratories. The ultimate choice of an assay method for benzodiazepines will be determined by the clinical application (routine monitoring, pharmacokinetics, overdose, forensic medicine) and by the characteristics of the benzodiazepine, the expertise of the analyst, the equipment available, the desired sensitivity and specificity and the time involved in method development or adaptation and validation.

Toxicity in a case of acute and massive overdose of chlordiazepoxide and its correlation to blood concentration

In previous studies no correlation between blood concentration and toxicity was found in acute chlordiazepoxide overdose. We describe a case of acute overdosage with 5.2 g chlordiazepoxide, in which toxicity correlated to blood concentration of the second metabolite of chlordiazepoxide, to demoxepam. Therefore, it is recommended to determine not only chlordiazepoxide, but also its active metabolites in cases of overdose. This can easily been achieved using the described method, HPLC with photodiode array detection.

Determination of diazepam and its pharmacologically active metabolites in blood by bond Elut column extraction and reversed-phase high-performance liquid chromatography

A rapid and quantitative analytical micro method for the determination of diazepam and its major pharmacologically active metabolites utilizing high-performance liquid chromatography (HPLC) is reported. The drug and its metabolites were extracted from 50-100 microliter samples of whole blood, serum or plasma using Bond Elut C 18 column and quantitated by high-performance liquid chromatography, using Technician Fast-LC-C-8 (RP 5 micrometers) bonded column and a mobile phase consisting of 53% methanol, 1% acetonitrile in KH2PO4 buffer and 10 microliters/l triethylamine. Methyl nitrazepam and medazepam were used as internal and external standards respectively. The extraction and recovery of diazepam and its major pharmacologically active metabolites, i.e., 3-hydroxydiazepam, desmethyldiazepam and oxazepam from blood were higher than 88% for all compounds. The minimum detection range of each compound was approximately 2.5 ng per 100-microliter sample. This micro method of simultaneous quantitation of diazepam and its major pharmacologically active metabolites provides a valuable technique for the study of diazepam pharmacokinetics in a small animal model without disturbance of normal hemodynamics from excess blood loss, as well as in clinical evaluation of pediatric patients.

High-pressure liquid chromatographic determination of chloridazepoxide and its major metabolites in biological fluids

A simple, isocratic, reversed-phase, high-pressure liquid chromatographic procedure was developed for the determination of chlordiazepoxide and its major metabolites in plasma and urine. The within-run coefficient of variation was 3.4-8.0%, and the day-to-day variation was 4.0-8.0%. Recoveries of 80-91% with sensitivity limits of 50 ng/ml were obtained for the parent drug and its metabolites. Plasma and urine samples collected after single intravenous and single oral doses were analyzed using this procedure.

The episodic nature of anxiety and its treatment with oxazepam

The presentation of anxiety in clinical practice is examined, and it is concluded that many patients, perhaps a majority, experience fluctuating levels of anxiety. It is therefore suggested that therapy should be intermittent, according to this waxing and waning of symptoms. Most benzodiazepines are long-acting, and are therefore unsuitable for this type of therapy, but oxazepam, which is short-acting and has no active metabolites, is ideal for this purpose. It is proposed that such a regimen would minimize the problems of over-sedation, psychological habituation, and a reluctance, due to a permanently tranquillized state, to deal with the root causes of the anxiety.

Thin-layer detection of diazepam and/or chilordiazepoxide alone or in combination with major drugs of abuse in drug abuse urine screening programs

Three extraction procedures for the detection of diazepam, oxazepam, chlorazepate and/or chlordiazepoxide in human urines are presented. All three procedures are based on the acid hydrolysis of benzodiazepines and/or their conjugated metabolites to give the corresponding benzophenones. Procedure I involves the direct acid hydrolysis of raw urine and is recommended when the aim is to test the abuse of benzodiazepine derivatives only. Procedure II Is a two-step extraction method in which a wide variety of drugs of abuse including cocaine (test based on the detection of benzoylecgonine) are extracted by the first step using paper loaded with cation-exchange resin and the benzodiazepines are tested in the second step by the acid hydrolysis of the spent urine left after removing the ion-exchange paper. Procedure III involves the use of inert fibrous matrix and then its acid hydrolysis. The detection procedure is based on the identification of methylaminochlorobenzophenone (MACB) and aminochlorobenzophenone (ACB). MACB is detected as a yellow-colored compound while ACB is detected by spraying with Bratton-Marshall reagent. Specificity of detection of ACB has been achieved by the selection of a thin-layer developing solvent system in which sulfonamides with primary aromatic amino groups remain at the origin.

Determination of chlordiazepoxide, diazepam, and their major metabolites in blood or plasma by spectrophotodensitometry

An analytical procedure was developed for the determination of chlordiazepoxide, diazepam and their major metabolites in blood or plasma. Demoxepam, a metabolite of chlordiazepoxide, is determined by spectrofluorometry after extraction. The remaining compounds are determined by spectrophotodensitometry after thin-layer chromatographic separation. The sensitivity limit of the spectrofluorometric determination of demoxepam is 0.1 to 0.2 microgram while that of the spectrophotodensitometric determination of chlordiazepoxide, diazepam and their N-desmethyl metabolites is 0.05 to 0.2 microgram. The sensitivity and specificity of the assay renders it suitable for monitoring plasma levels of chlordiazepoxide and its major metabolites following single or chronic oral administration of chlordiazepoxide hydrochloride. The sensitivity limit for diazepam and nordiazepam, its major metabolite, renders the assay useful only for the determination of plasma concentrations resulting from high dosage of diazepam. The assay was used to determine chlordiazepoxide and its metabolites following oral administration of Librium. The data showed a significant correlation to those obtained on the same specimens by differential pulse polarography and by radioimmunoassay.