Quantification of chlordesmethyldiazepam by liquid chromatography-tandem mass spectrometry: application to a cloxazolam bioequivalence study.

A rapid, sensitive and specific LC-MS/MS method was developed and validated for quantifying chlordesmethyldiazepam (CDDZ or delorazepam), the active metabolite of cloxazolam, in human plasma. In the analytical assay, bromazepam (internal standard) and CDDZ were extracted using a liquid-liquid extraction (diethyl-ether/hexane, 80/20, v/v) procedure. The LC-MS/MS method on a RP-C18 column had an overall run time of 5.0 min and was linear (1/x weighted) over the range 0.5-50 ng/mL (R > 0.999). The between-run precision was 8.0% (1.5 ng/mL), 7.6% (9 ng/mL), 7.4% (40 ng/mL), and 10.9% at the low limit of quantification-LLOQ (0.500 ng/mL). The between-run accuracies were 0.1, -1.5, -2.7 and 8.7% for the above mentioned concentrations, respectively. All current bioanalytical method validation requirements (FDA and ANVISA) were achieved and it was applied to the bioequivalence study (Cloxazolam -- test, Eurofarma Lab. Ltda and Olcadil -- reference, Novartis Biociências S/A). The relative bioavailability between both formulations was assessed by calculating individual test/reference ratios for Cmax, AUClast and AUC0-inf. The pharmacokinetic profiles indicated bioequivalence since all ratios were as proposed by FDA and ANVISA.

Effect of orally administered misoprostol and cimetidine on the steady state pharmacokinetics of diazepam and nordiazepam in human volunteers.

The effects of misoprostol and cimetidine on diazepam pharmacokinetics were evaluated in order to determine whether the kinetic variables for diazepam and nordiazepam alone differ with the repeated oral administration of misoprostol and cimetidine to healthy adult volunteers. The trial was conducted as an open crossover study in 12 normal subjects, divided into two groups with all subjects receiving both regimens. Total study duration was 5 weeks. An initial clinical assessment, including blood biochemistry and assessment of subject oxidation status was carried out on study day 1. On this day, subjects began taking diazepam (10 mg) orally for one week, with pharmacokinetic studies performed at day 8, when steady state levels of diazepam were reached. This was followed by one week with active drug, misoprostol to Group I and cimetidine to Group II, with pharmacokinetic studies performed at the end of a 1-week treatment. After a 2-week wash-out period, both groups took for one week, the alternate drug, i.e. cimetidine plus diazepam to Group I and misoprostol plus diazepam to Group II. On days 8, 15 and 36, subjects were admitted to the hospital for 12 h, during which time a clinical examination was carried out and blood samples were taken at time zero and at 4, 8, 12, 24, and 36 h post-dosing for the measurement of serum diazepam and nordiazepam. The main parameters measured and evaluated were diazepam and nordiazepam pharmacokinetics at steady state (days 8, 15 and 36). These were areas under the curve in the dose intervals (AUC0-24h), maximum plasma concentrations (Cmax), time to peak concentrations (Tmax), elimination half-life (t1/2), elimination constant (Kel), distribution volume (Vd), total body clearance (ClB) and clearance after oral administration (Cloral). The results demonstrated that plasma diazepam and nordiazepam concentrations had a significant increase after steady states have been reached with the simultaneous administration of 800 mg of cimetidine daily for one week. The simultaneous administration of 800 micrograms of misoprostol did not cause any significant change in diazepam and nordiazepam plasma levels after steady states had been reached. Comparing the pharmacokinetic parameters of Groups A and B as well as within groups on days 8, 15 and 36, a significant increase in plasma diazepam and nordiazepam levels was detected. This was due to a cimetidine-induced impairment in microsomal oxidation of diazepam and nordiazepam, which caused a decrease in total metabolic clearance and increased mean steady state plasma concentrations. A more prolonged half-life was observed for both groups taking cimetidine as well as an increase of mean maximum plasma concentrations.(ABSTRACT TRUNCATED AT 400 WORDS)

Determinaçäo de diazepam e de N-desmetildiazepam em sangue humano "post-mortem" por cromatografia em fase gasosa com detector de captura de elétrons / Determination of diazepam and N-desmethyldiazepam in post-mortem human blood by electron-capture gas-liquid chromatography

Os autores descrevem um método para determinaçäo simultânea de diazepam e de N-desmetildiazepam em sangue humano "post-morten" por cromatografia em fase gasosa. Após adiçäo de medazepam como padräo interno, 0,5ml de amostra de sangue säo estraídas a pH 9,0 com igual volume de acetato de etila. Alíquotas do sobrenadante säo submetidas a cromatolgrafia em fase gasosa com dectetor de captura de elétrons, usando-se uma coluna de vidro contendo Chromosorb (HP) 80-100 "mesh" silanisado como suporte sólido e OV-17 3% como fase estacionária. O método além de simples, rápido, sensível e preciso (CV%<5), apresentou uma linearidade de 31,25 a 1.000ng/ml e uma recuperaçäo da ordem de 97 e 94% para dizepam e N-desmetildiazepam, respectivamente

[Treatment of epileptic crisis with chlorazepate dipotassium. Clinical study of 48 patients with the determination of serum levels of nordiazepam]. / Tratamiento de las crisis epilépticas con clorazepato dipotásico. Estudio clinico de 48 pacientes con determinación de niveles séricos de nordiazepam.

48 patients with several types of seizures (following the international classification of epileptic seizures), were studied. Dipotassium chlorazepate was administered as a secondary antiepileptic drug. The cases were selected due to the severity of their seizures. The therapeutic results were evaluated with a daily record of seizures and attempt was made to correlate the serum levels of nordiazepam with the clinical results.