Determination of lorazepam in plasma from children by high-performance liquid chromatography with UV detection

Analytical methods for determination of benzodiazepines. A short review

Benzodiazepines (BDZs) are generally commonly used as anxiolytic and/or hypnotic drugs as a ligand of the GABAA-benzodiazepine receptor. Moreover, some of benzodiazepines are widely used as an anti-depressive and sedative drugs, and also as anti-epileptic drugs and in some cases can be useful as an adjunct treatment in refractory epilepsies or anti-alcoholic therapy. High-performance liquid chromatography (HPLC) methods, thin-layer chromatography (TLC) methods, gas chromatography (GC) methods, capillary electrophoresis (CE) methods and some of spectrophotometric and spectrofluorometric methods were developed and have been extensively applied to the analysis of number of benzodiazepine derivative drugs (BDZs) providing reliable and accurate results. The available chemical methods for the determination of BDZs in biological materials and pharmaceutical formulations are reviewed in this work.

Benzodiazepines: sample preparation and HPLC methods for their determination in biological samples

Benzodiazepines (BDZs) belong to a group of substances known for their sedative, antidepressive, muscle relaxant, tranquilizer, hypnotic and anticonvulsant properties. Their determination in biological fluids is essential in clinical assays as well as in forensics and toxicological studies. Researchers focus on the development of rapid, accurate, precise and sensitive methods for the determination of BDZs and their metabolites. A large number of analytical methods using different techniques have been reported, but none can be considered as the method of choice. BDZs are usually present at trace levels (microgram or nanogram per milliliter) in a complex biological matrix and the potentially interfering compounds must be isolated by various extraction techniques before analysis. An extended and comprehensive review is presented herein, focusing on sample preparation (pretreatment and extraction) and HPLC conditions applied by different authors. These methods enable bioanalysts to achieve detection limits down to 1-2 ng/ml using UV/diode array detection, readily available in most laboratories, and better than 1 ng/ml using electron capture detection, which is lower than that obtained using a nitrogen phosphorus detector. MS interfaced with electrospray ionization offered a similar sensitivity, while negative chemical ionization MS or sonic spray ionization MS provided sensitivity down to 0.1 ng/ml.

Pharmacokinetics and clinical efficacy of lorazepam in children with severe malaria and convulsions

AIM

To investigate the pharmacokinetics and clinical efficacy of intravenous (i.v.) and intramuscular (i.m.) lorazepam (LZP) in children with severe malaria and convulsions.

METHODS

Twenty-six children with severe malaria and convulsions lasting > or =5 min were studied. Fifteen children were given a single dose (0.1 mg kg(-1)) of i.v. LZP and 11 received a similar i.m. dose. Blood samples were collected over 72 h for determination of plasma LZP concentrations. Plasma LZP concentration-time data were fitted using compartmental models.

RESULTS

Median [95% confidence interval (CI)] LZP concentrations of 65.1 ng ml(-1) (50.2, 107.0) and 41.4 ng ml(-1) (22.0, 103.0) were attained within median (95% CI) times of 30 min (10, 40) and 25 min (20, 60) following i.v. and i.m. administration, respectively. Concentrations were maintained above the reported therapeutic concentration (30 ng ml(-1)) for at least 8 h after dosing via either route. The relative bioavailability of i.m. LZP was 89%. A single dose of LZP was effective for rapid termination of convulsions in all children and prevention of seizure recurrence for >72 h in 11 of 15 children (73%, i.v.) and 10 of 11 children (91%, i.m), without any clinically apparent respiratory depression or hypotension. Three children (12%) died.

CONCLUSION

Administration of LZP (0.1 mg kg(-1)) resulted in rapid achievement of plasma LZP concentrations within the reported effective therapeutic range without significant cardiorespiratory effects. I.m administration of LZP may be more practical in rural healthcare facilities in Africa, where venous access may not be feasible.