What is Ambien?
Ambien (or zolpidem) – is an organic chemical compound, a short-acting hypnotic of the imidazopyridine group. It is used in the immediate treatment of insomnia. It works quickly (usually within 15-30 minutes of administration) and has a short biological half-life (2-3 hours). Its hypnotic properties and action are similar to those of benzodiazepines, but they work much more selectively.
In case of overdose, flumazenil is used, which is an antagonist of benzodiazepine receptors, and also reverses the soporific and intoxicating effects of zolpidem. High doses of zolpidem can cause memory problems, complete amnesia or even hallucinations.
Zolpidem has a characteristic high selective affinity for the α1-subunit of the GABA A receptor. The selectivity is about 10-fold against the α2 and α3 subunits . This partially explains the unusual properties of zolpidem:
the dominant hypnotic effect with a significantly weaker anti-anxiety and almost imperceptible anti-convulsive effect – in therapeutic doses, side effects like sleepwalking in some patients or perceptual changes compared to benzodiazepines, which bind to all three subunits much less selectively and with similar affinities. This is why, for example, the above-mentioned lunatism almost never occurs, even in the elderly, after the use of benzo-1,4-diazepine derivatives (such as midazolam or estazolam.)
Zolpidem is sold in the form of a salt with tartaric acid. In Poland, this drug is issued only on the basis of a medical prescription with the written total amount of active substance on which no other medicines are prescribed.
In the body, zolpidem undergoes metabolism, and 3 main inactive metabolites are formed, resulting from the oxidation of methyl to carboxyl groups in the imidazopyridine system.
Metabolism occurs with the participation of the cytochrome P450 hepatic system; substances modifying the activity of this cytochrome may strongly affect the rate of metabolism of zolpidem, rifampicin (a strong cytochrome P450 inducer) may reduce the plasma zolpidem concentration by up to 60%, significantly weakening the therapeutic effect.
These metabolites are excreted from the body by the kidneys.
Like benzodiazepines, zolpidem is occasionally misused to cause intoxication; the effects are difficult to predict and the amnesia most often ends.
The narcotic properties of zolpidem are weakening with each subsequent dose, usually at the 3rd or 4th dose adopted in a short space of time (usually shorter than two months) only hypnotic effects are noticeable.
The following may occur:
- post-secondary amnesia,
- nausea and vomiting (especially if the standard dose of 10 mg is exceeded),
- lunatism (the mind then remains in the slow-wave sleep phase, but the body is not dormant),
- daytime sleepiness (very rare).
Zolpidem is an extremely safe medicine when it comes to the possibility of overdose, eg for suicide. No persistent sequelae after a 400 mg dose (40 times the standard sleeping dose) – these amounts must actually cause nausea and vomiting, making a fatal overdose with highly unlikely zolpidem. Nevertheless, consciousness disorders were observed up to coma (in extreme cases). There is no specific antidote and haemodialysis and hemoperfusion are ineffective. If necessary, intravenous flumazenil may be administered to suppress excessive effects.