Automated solid-phase extraction and liquid chromatography-electrospray ionization-mass spectrometry for the determination of flunitrazepam and its metabolites in human urine and plasma samples.

A sensitive and specific method using reversed-phase liquid chromatography coupled with electrospray ionization-mass spectrometry (LC-ESI-MS) has been developed for the quantitative determination of flunitrazepam (F) and its metabolites 7-aminoflunitrazepam (7-AF), N-desmethylflunitrazepam (N-DMF) and 3-hydroxyflunitrazepam (3-OHF) in biological fluids. After the addition of deuterium labelled standards of F,7-AF and N-DMF, the drugs were isolated from urine or plasma by automated solid-phase extraction, then chromatographed in an isocratic elution mode with a salt-free eluent. The quantification was performed using selected ion monitoring of protonated molecular ions (M+H(+)). Experiments were carried out to improve the extraction recovery (81-100%) and the sensitivity (limit of detection 0.025 ng/ml for F and 7-AF, 0.040 ng/ml for N-DMF and 0.200 ng/ml for 3-OHF). The method was applied to the determination of F and metabolites in drug addicts including withdrawal urine samples and in one date-rape plasma and urine sample.

Compared efficacy of diazepam or avizafone to prevent soman-induced electroencephalographic disturbances and neuropathology in primates: relationship to plasmatic benzodiazepine pharmacokinetics.

We performed an experiment to characterize the toxicity of soman in cynomolgus monkeys in which organophosphorus intoxication was followed by treatment with either the current three-drug therapy atropine/pralidoxime/diazepam or a combination of atropine/pralidoxime/avizafone, avizafone being the water soluble prodrug of diazepam. Clinical, electrophysiological, and histological approaches were combined. When benzodiazepines were injected at the similar molar dose of 0.7 micromol/kg, the protection against soman toxicity was better with the atropine/ pralidoxime/diazepam combination than with the atropine/pralidoxime/avizafone one. Pharmacokinetic studies demonstrated that this difference of efficacy could be explained by a lower plasmatic load of diazepam obtained after injection of avizafone at 0.7 micromol/kg, compared to the administration of diazepam at the same molar dose. Moreover, after injection of avizafone, plasmatic levels of diazepam were achieved faster and declined more rapidly than after administration of diazepam. Compared to diazepam given at a dose of 0.7 micromol/kg, injection of 1 micromol avizafone/kg gave a similar plasmatic load of benzodiazepine, but with a lower time to maximum plasma concentration (tmax) and a higher maximum plasma concentration (Cmax) for plasmatic diazepam. We therefore went on to demonstrate that administration of the atropine/pralidoxime/avizafone combination at a dose 1 micromol benzodiazepine/kg to intoxicated monkeys afforded electrophysiological and histological protection similar to that obtained after administration of atropine/pralidoxime/diazepam at a dose of 0.7 micromol diazepam/kg. Reflections on the possible incorporation of avizafone in three-drug emergency treatment are presented.

Direct analysis of fluoxetine and norfluoxetine in plasma by gas chromatography with nitrogen-phosphorus detection.

A quantitative method for the simultaneous GC resolution and detection of fluoxetine and his metabolite norfluoxetine in human plasma was developed. The procedure required 1.0 ml of plasma, extraction with a mixed organic solvent and injection into a capillary gas chromatograph with an OV-1 fused-silica column coupled to a nitrogen-phosphorus detector. The calibration curves were linear over the range 5-3000 ng/ml. The detection limits were 0.3 and 2 ng/ml for fluoxetine and norfluoxetine, respectively. The assay is suitable for routine analysis.

Simultaneous determination of zolpidem and zopiclone in human plasma by gas chromatography-nitrogen-phosphorus detection.

A simple, specific and selective method for the simultaneous determination of zolpidem and zopiclone in human plasma is described. After a liquid-liquid extraction, the extract is injected into a capillary gas chromatograph with an OV-1 fused-silica column coupled to a nitrogen-phosphorus detector. The detection limits are 1 and 2 ng/ml for zolpidem and zopiclone, respectively. The method described is reproducible and linear over a range of concentrations, rendering it suitable for use for pharmacokinetic studies or toxicological evaluations. Absolute identification of the chromatographed compounds is accomplished by gas chromatography--mass spectrometry in both electron-impact and positive-ion chemical ionisation modes.

Simultaneous determination of trimipramine and desmethyl- and hydroxytrimipramine in plasma and red blood cells by capillary gas chromatography with nitrogen-selective detection.

A simple procedure is described that permits the simultaneous determination of trimipramine and its two major metabolites, desmethyl- and hydroxytrimipramine, in human plasma or red blood cells (RBCs) at therapeutic concentrations. The extracted biological fluids are injected into a capillary gas chromatograph with an OV-1 fused-silica column coupled to a nitrogen-phosphorus-selective detector. The limit of determination for trimipramine is 3 ng/ml and for that desmethyl- and hydroxytrimipramine is 4 ng/ml. The method permits the RBC/plasma ratios to be determined and to be correlated with the clinical response.

Intrarectal diazepam in epileptic adults.

Intrarectally (i.r.) administered diazepam (DZP) solution at doses of 20 and 30 mg in the treatment of serial seizures was studied in 39 adult patients with refractory partial epilepsy. Patients were randomly distributed into two groups (20 mg, n = 21; 30 mg, n = 18). Plasma levels of DZP were assessed over 24 h following i.r. injection. The efficacy of i.r. DZP in the treatment of serial seizures in adults was confirmed; onset of effect was noted approximately 10 min after the injection, and the effective dose was 0.50 mg/kg. Tolerance and acceptability were good. Intrarectal injection of DZP can be performed even by unskilled personnel and may be recommended in patients with serial seizures in the hope of preventing development of status epilepticus.