Etizolam

Etizolam is a thienotriazolodiazepine with pharmacological effects similar to those of benzodiazepines. It has been used medically in countries including Japan, South Korea and Italy for anxiety and related conditions, but it is also encountered as a non-medical drug and in illicitly manufactured tablets. Its effects include anxiolysis, sedation, muscle relaxation and memory impairment. Most serious harms reported in recent years have involved illicit products or combinations with other depressants.

Chemistry and medical history

Etizolam differs from conventional benzodiazepines because a thiophene ring replaces the fused benzene ring, while a triazole ring is fused to the diazepine structure. This makes it a thienotriazolodiazepine rather than a classical 1,4-benzodiazepine, although its pharmacological action is similar.

Etizolam was developed in Japan and marketed there under the name Depas from 1984. It has also been authorised in some other countries, including South Korea and Italy. Outside these medical markets, it has appeared as a new psychoactive substance and in counterfeit tablets sold as pharmaceutical benzodiazepines.

Pharmacology

Etizolam is a positive allosteric modulator at the benzodiazepine site of the GABA_A receptor. It increases the effect of GABA, reducing neuronal excitability. Its clinical effects include anxiolysis, sedation, muscle relaxation and anticonvulsant activity.

Etizolam is metabolised mainly through hydroxylation. Two major metabolites, α-hydroxyetizolam and 8-hydroxyetizolam, have been identified in biological samples. The CYP3A4 enzyme is involved in its metabolism, and drugs that inhibit or induce this enzyme can alter etizolam exposure (Al Bahri and Hamnett, 2023).

Subjective effects

The PsychonautWiki profile of etizolam includes user accounts of relatively rapid sedation and anxiety relief. Relaxation, disinhibition and euphoria appear alongside sleepiness, impaired coordination and memory suppression.

Physical effects

Sedation and muscle relaxation are prominent. Some users describe a rapid reduction in physical tension, while others report dizziness, reduced coordination and heavy sleepiness. Respiratory depression is a recognised risk, particularly when etizolam is combined with other central nervous system depressants.

Cognitive effects

Anxiety suppression is one of the main reported effects. Disinhibition and a feeling of emotional relief may occur, sometimes accompanied by mild euphoria. Memory suppression, slowed thinking and reduced alertness can also appear. Some users report compulsive redosing, especially when the initial subjective effects seem to have worn off before impairment has fully resolved.

Clinical use and non-medical harms

Etizolam has a longer history of medical use than most designer benzodiazepines. A rapid review of its pharmacology and harms found relatively few adverse effects associated with regulated therapeutic use. The harms reported in recent years were more often linked to illicitly manufactured tablets, uncertain contents and combinations with other substances (Nielsen and colleagues, 2020).

Forensic reports have identified etizolam in impaired-driving cases, emergency presentations and post-mortem investigations. In many fatal cases, other drugs were also present, making it difficult to attribute the outcome to etizolam alone. The risk is particularly concerning when it is combined with opioids or alcohol, which can intensify respiratory and central nervous system depression.

Tolerance and dependence

Etizolam can produce tolerance and physical dependence, as can other benzodiazepines. Withdrawal after regular use may involve rebound anxiety, insomnia, agitation and, in severe cases, seizures. Abrupt discontinuation can be dangerous for a dependent person and requires medical advice.

Related compounds

Etizolam is related to Deschloroetizolam and Metizolam, which share the thienodiazepine framework. It is pharmacologically similar to conventional benzodiazepines such as alprazolam, despite its different ring structure.