Pharmacology
Mechanism of action
Zaleplon is a high-affinity ligand of positive modulator sites of GABAA receptors, which enhances GABAergic inhibition of neurotransmission in the central nervous system. The ultrashort half-life gives zaleplon a unique advantage over other hypnotics because of its lack of next-day residual effects on driving and other performance-related skills. Unlike nonselective benzodiazepine drugs and zopiclone, which distort the sleep pattern, zaleplon appears to induce sleep without disrupting the natural sleep architecture.A meta-analysis of randomized, controlled clinical trials which compared benzodiazepines against zaleplon or other Z-drugs such as zolpidem, zopiclone, and eszopiclone has found few clear and consistent differences between zaleplon and the benzodiazepines in terms of sleep onset latency, total sleep duration, number of awakenings, quality of sleep, adverse events, tolerance, rebound insomnia, and daytime alertness.Zaleplon has a pharmacological profile similar to benzodiazepines, characterized by an increase in slow wave deep sleep (SWDS) with rapid onset of hypnotic action. Zaleplon is a full agonist for the benzodiazepine α1 receptor located on the GABAA receptor complex in the body, with lower affinity for the α2 and α3 subsites. It selectively enhances the action of GABA similar to, but more selectively than benzodiazepines. Zaleplon, although not a benzodiazepine, maintains a very similar pharmacological profile nonetheless, known for inducing hypnotic effects by α1 subreceptor sites, anxiolytic and muscle relaxant effects via α2 and α3 subsites, with negligible anticonvulsant properties (via α5 subsite), as zaleplon action is modulated at benzodiazepine receptor sites. The elimination half-life of zaleplon is about 1–1.5 hours.
Society and culture
Recreational use
Zaleplon has the potential to be a drug of recreational use, and has been found to have an addictive potential similar to benzodiazepine and benzodiazepine-like hypnotics. The mind- and judgment-altering effects of zaleplon are similar to those of many benzodiazepines, but the fast-acting nature and short half-life of the chemical mean high doses set on much more quickly and last for short periods of time (usually from 45 to 60 minutes). Some individuals use a different delivery method than prescribed, such as insufflation, to induce effects faster. A common effect of recreational zaleplon use is the occurrence of (typically short-lived) hallucinations. Fewer visual and auditory hallucinations/disruptions occur with the use of zaleplon than with other Z-drugs, like zolpidem. Anterograde amnesia can occur and can cause one to lose track of the amount of zaleplon already ingested, prompting the ingesting of more than originally planned. However, continuous ingestion is extremely unlikely precisely because of zaleplons quick onset of action.The combination of alcohol and zaleplon can result in fatal respiratory depression and asphyxiation from vomiting. Aviation use
The Federal Aviation Administration allows zaleplon with a 12-hour wait period and no more than twice a week, which makes it the sleep medication with the shortest allowed waiting period after use. The substances with the 2nd shortest period, which is of 24 hours, are zolpidem and ramelteon.