Pharmacodynamics
In the central nervous system, zolpidem binds with high affinity to the α- and γ-subunit of the GABAA receptor, interacts with it, and enhances the sedative and sleep-promoting responses of the neurotransmitter GABA (gamma-amino-butyric acid). This triggers muscle relaxant and anticonvulsant effects and facilitates sleep onset and duration.
Pharmacokinetics
The hypnotic is rapidly absorbed from the gastrointestinal tract and acts quickly after oral administration. The bioavailability in this case is about 70%. In the blood, the maximum plasma concentration is reached after 0.5-3 hours and it circulates about 90% bound to proteins. The volume of distribution is 0.54-0.68 l/kg, decreasing in the elderly and increasing in patients with chronic renal insufficiency.
Zolpidem is metabolized in the liver by various cytochrome P450 isoenzymes into inactive metabolites, which are excreted mainly by the kidneys. The half-life averages 2.4 hours.
Drug Interactions
While taking zolpidem, interactions may occur with alcohol, centrally depressant drugs and antidepressants(bupropion, desipramine, venlafaxine, sertraline, fluoxetine), fluvoxamine, narcoanalgesics, ciprofloxacin, and drugs metabolized by CYP3A4 and CYP450.