Valium

Generic name of Valium — Diazepam

Diazepam first marketed as Valium by Hoffmann-La Roche, is a drug which is a benzodiazepine derivative. It possesses anxiolytic, anticonvulsant, sedative, skeletal muscle relaxant and amnestic properties. This makes it a useful drug for treating anxiety, insomnia, seizures, alcohol withdrawal, and muscle spasms. It is also used before certain medical procedures (such as endoscopies) to reduce tension and anxiety, and in some surgical procedures to induce amnesia.

Diazepam can be administered orally, intravenously, intramuscularly, or as a suppository.

When diazepam is administered orally, it is rapidly absorbed and has a fast onset of action. The onset of action is 1-5 minutes for IV administration and 15-30 minutes for IM administration. The duration of the diazepam’s main pharmacological effects is 15 minutes to 1 hour for both routes of administration.

Peak plasma levels are achieved 30 minutes to 2 hours after oral administration. When diazepam is administered as an intramuscular injection, absorption is slow, erratic and incomplete.

Diazepam is highly lipid-soluble, and is widely distributed throughout the body after administration. It easily crosses both the blood-brain barrier and the placenta, and is excreted into breast milk. After absorption, diazepam is redistributed into muscle and adipose tissue. Continual daily doses of diazepam will quickly build up to a high concentration in the body (mainly in adipose tissue), which will be far in excess of the actual dose for any given day.

There is preferential storage of diazepam in some organs including the heart. Absortion by any administered route and the risk of accumulation is significantly increased in the neonate and there are clinical justification to recommend the withdrawal of diazepam during pregnancy and breast feeding.

Diazepam is metabolised in the liver via the cytochrome P450 enzyme system. It has a biphasic half-life of 1-2 and 2-5 days, and has several pharmacologically active metabolites. The main active metabolite of diazepam is desmethyldiazepam (also known as nordazepam or nordiazepam). Diazepam’s other active metabolites include temazepam and oxazepam. These metabolites are conjugated with glucuronide, and are excreted primarily in the urine. Because of these active metabolites, the serum values of diazepam alone are not useful in predicting the effects of the drug.

Diazepam has a half-life (t1/2?) of 20-50 hours, and desmethyldiazepam has a half-life of 30-200 hours.

Most of the drug is metabolised; very little diazepam is excreted unchanged.

In humans, the protein binding of diazepam is around 98.5%.

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