Estazolam

Estazolam (marketed under the brand names ProSom, Eurodin) is a drug which is a benzodiazepine derivative. It possesses anxiolytic, anticonvulsant, sedative and skeletal muscle relaxant properties. Estazolam is an intermediate-acting oral benzodiazepine.

It is commonly prescribed for short-term treatment of insomnia.

Pharmacology
Estazolam is classed as a "triazolo" benzodiazepine drug. An animal study demonstrated that estazolam induces a drowsy pattern of spontaneous EEG including high voltage slow waves and spindle bursts increase in the cortex and amygdala, while the hippocampal theta rhythm is desynchronized. Also low voltage fast waves occur particularly in the cortical EEG. The EEG arousal response to auditory stimulation and to electric stimulation of the mesencephalic reticular formation, posterior hypothalamus and centromedian thalamus is significantly suppressed. The photic driving response elicited by a flash light in the visual cortex is significantly suppressed by estazolam. Estazolam at high doses decreases histamine turnover via it's action at the benzodiazepine-GABA receptor complex.

Estazolam and other benzodiazepines may influence neurosteroid metabolism which in turn may influence the functions of the brain and reproductive system. The pharmacological actions of benzodiazepines at the GABAa receptor are similar to those of neurosteroids. Neuroactive steroids are positive allosteric modulators of the GABAa receptor, enhancing GABA function. Many hypnotic benzodiazepines (nimetazepam, temazepam, estazolam, flunitrazepam and nitrazepam) potently inhibit the enzymes involved in the metabolism of neurosteroids. Long-term administration of benzodiazepines may influence the concentrations of endogenous neurosteroids, and thereby would modulate the emotional state. Factors which effects benzodiazepines ability to alter neurosteroid levels depend on the molecular make up of the individual benzodiazepine. Presence of a substituent at N1 position of the diazepine ring and/or the chloro or nitro group at position 7 of the benzene ring contribute to potent inhibition of the isoenzymes, and in turn a bromo group at position 7 (for bromazepam) and additional substituents (3-hydroxy group for oxazepam and tetrahydroxazole ring for cloxazolam and oxazolam) decrease the inhibitory potency.

Abuse
Estazolam became notorious in 1998 when a large amount of a 'herbal sleeping mix' called Sleeping Buddha was recalled from the shelves after the FDA descovered that it contained estazolam (as well as some heavy metal salts).