In rats, it triggered the release of vasopressin into paraventricular nucleus of the hypothalamus and decreased the release of ACTH under stress. Pharmacokinetics
Oral administration of 15 to 45 mg of temazepam in humans resulted in rapid absorption with significant blood levels achieved in fewer than 30 minutes and peak levels at two to three hours.In a single- and multiple-dose absorption, distribution, metabolism, and excretion (ADME) study, using tritium-labelled drug, temazepam was well absorbed and found to have minimal (8%) first-pass drug metabolism. No active metabolites were formed and the only significant metabolite present in blood was the O-conjugate. The unchanged drug was 96% bound to plasma proteins. The blood-level decline of the parent drug was biphasic, with the short half-life ranging from 0.4 to 0.6 hours and the terminal half-life from 3.5 to 18.4 hours (mean 8.8 hours), depending on the study population and method of determination.Temazepam has very good bioavailability, with almost 100% being absorbed following being taken by mouth. The drug is metabolized through conjugation and demethylation prior to excretion. Most of the drug is excreted in the urine, with about 20% appearing in the faeces. The major metabolite was the O-conjugate of temazepam (90%); the O-conjugate of N-desmethyl temazepam was a minor metabolite (7%). Chemistry
Temazepam is a benzodiazepine. It is a white, crystalline substance, very slightly soluble in water, and sparingly soluble in alcohol. Synthesis
Pharmacologically active metabolite of diazepam, q.v. N-oxides are prone to undergo the Polonovski rearrangement when treated with acetic anhydride, and this was illustrated by the synthesis of oxazepam.
All test subjects consistently showed a strong preference for temazepam and triazolam over all the rest of the benzodiazepines included in the study. North America
In North America, temazepam misuse is not widespread. Other benzodiazepines are more commonly prescribed for insomnia. In the United States, temazepam is the fifth-most prescribed benzodiazepine, however there is a major drop off from the top four most prescribed (alprazolam, lorazepam, diazepam, and clonazepam in that order). Individuals abusing benzodiazepines obtain the drug by getting prescriptions from several doctors, forging prescriptions, or buying diverted pharmaceutical products on the illicit market. North America has never had a serious problem with temazepam misuse, but is becoming increasingly vulnerable to the illicit trade of temazepam. Australia
Temazepam is a Schedule 4 drug and requires a prescription. The drug accounts for most benzodiazepine sought by forgery of prescriptions and through pharmacy burglary in Victoria. Due to rife intravenous abuse, the Australian government decided to put it under a more restrictive schedule than it had been, and since March 2004 temazepam capsules have been withdrawn from the Australian market, leaving only 10 mg tablets available.Benzodiazepines are commonly detected by Customs at different ports and airports, arriving by mail, also found occasionally in the baggage of air passengers, mostly small or medium quantities (up to 200–300 tablets) for personal use. From 2003 to 2006, customs detected about 500 illegal importations of benzodiazepines per year, most frequently diazepam. Quantities varied from single tablets to 2,000 tablets.