Oxazepam

Oxazepam is a benzodiazepine tranquilliser. It is used in the short-term treatment of anxiety.

Oxazepam is rapidly and almost completely absorbed from the GI tract and is highly protein bound (approximately 90%). It has been reported to have a half-life ranging from about 6-20 hours. It is the ultimate pharmacologically active metabolite of diazepam and is metabolised by a simple one-step process to a pharmacologically inert compound, glucuronide. Peak serum levels are reached in 1-5 hours.

Oxazepam crosses the placental barrier and is excreted in breast milk; lethargy and weight loss may occur in breast fed infants.

Acute oral LD50 in mice is greater than 5000 mg/kg.

Fatty metamorphosis of the liver has been noted in six-week toxicity studies in rats given this product at 0.5% of the diet. Such accumulations of fat are considered reversible, since no liver necrosis or fibrosis is seen.

In vitro mutagenicity reports on Oxazepam are inconclusive.

In a carcinogenicity study, oxazepam was administered with diet to rats for two years. Male rats receiving 30 times the maximum human dose showed a statistical increase, when compared to controls, in benign thyroid follicular cell tumours, testicular interstitial cell adenomas, and prostatic adenomas. An earlier published study reported that mice fed dietary dosages of 35 or 100 times the human daily dose of oxazepam for 9 months developed a dose-related increase in liver adenomas. In an independent analysis of some of the microscopic slides from this mouse study, several of these tumours were classified as liver carcinomas. At this time, there is no evidence that clinical use of oxazepam is associated with tumours.