Etizolam

DEA NFLIS-Drug Category -> Benzodiazepines

DEA Schedule I Controlled Substance -> Depressants

Pharmaceuticals -> Synthetic Cannabinoids or Psychoactive Compounds

Pharmaceuticals -> Listed in ZINC15

Danger

H315 (60%): Causes skin irritation [Warning Skin corrosion/irritation]

P203, P264, P264+P265, P280, P302+P352, P305+P351+P338, P318, P321, P332+P317, P337+P317, P362+P364, P405, and P501 (click each P-code to see the statement)

Aggregated GHS information provided per 65 reports by companies from 4 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

General supportive measures should be employed, along with intravenous fluids, and an adequate airway maintained. Hypotension may be combated by the use of norepinephrine or metaraminol. Dialysis is of limited value. Flumazenil (Anexate) is a competitive benzodiazepine receptor antagonist that can be used as an antidote for benzodiazepine overdose. In particular, flumazenil is very effective at reversing the CNS depression associated with benzodiazepines but is less effective at reversing respiratory depression. Its use, however, is controversial as it has numerous contraindications. It is contraindicated in patients who are on long-term benzodiazepines, those who have ingested a substance that lowers the seizure threshold, or in patients who have tachycardia or a history of seizures. As a general rule, medical observation and supportive care are the mainstay of treatment of benzodiazepine overdose. Although benzodiazepines are absorbed by activated charcoal, gastric decontamination with activated charcoal is not beneficial in pure benzodiazepine overdose as the risk of adverse effects often outweigh any potential benefit from the procedure. It is recommended only if benzodiazepines have been taken in combination with other drugs that may benefit from decontamination. Gastric lavage (stomach pumping) or whole bowel irrigation are also not recommended.

Benzodiazepines bind nonspecifically to benzodiazepine receptors BNZ1, which mediates sleep, and BNZ2, which affects affects muscle relaxation, anticonvulsant activity, motor coordination, and memory. As benzodiazepine receptors are thought to be coupled to gamma-aminobutyric acid-A (GABAA) receptors, this enhances the effects of GABA by increasing GABA affinity for the GABA receptor. Binding of the inhibitory neurotransmitter GABA to the site opens the chloride channel, resulting in a hyperpolarized cell membrane that prevents further excitation of the cell.

Drug-Induced Liver Injury Severity and Toxicity (DILIst)

Etizolam

DILI Positive

DOI:10.1016/j.drudis.2019.09.022

N - Nervous system

QN - Nervous system

Etizolam is a CNS depressant with anxiolytic, anticonvulsant, sedative-hypnotic and muscle relaxant effects. It acts on the benzodiazepine site of the GABA-A receptor as an agonist to increase inhibitory GABAergic transmission throughout the central nervous system. Studies indicate that etizolam mediates its pharmacological actions with 6 to 10 times more potency than that of diazepam. Clinical human studies performed in Italy showed clinical effectiveness of etizolam in relieving symptoms in patients with generalized anxiety disorders with depressive symptoms. Etizolam also mediates imipramine-like neuropharmacological and behavioral effects, as well as minor effects on cognitive functioning. It is shown to substitute the actions of a short-acting barbiturate, pentobarbitol, in a drug discrimination study. Etizolam is an antagonist at platelet-activating-factor (PAF) receptor and attenuates the recurrence of chronic subdural hematoma after neurosurgery in clinical studies. It is shown to inhibit PAF-induced bronchoconstriction and hypotension.

Etizolam is selectively a full agonist at GABA-A receptors to increase GABAergic transmission and enhance GABA-induced Cl- currents. It is reported to bind to the benzodiazepine binding site which is located across the interface between the alpha and gamma subunits. Benzodiazapines are reported to only bind to receptors that contain gamma 2 and alpha 1/2/3/5 subunits. Alpha-1-containing receptors mediate the sedative effects of etizolam whereas alpha-2 and alpha-3 subunit-containing receptors mediate the anxiolytic effect. Etizolam shows high potency and affinity towards GABA-A receptor with alpha 1 beta 2 gamma 2S subunit combination. By binding to the regulatory site of the receptor, etizolam potentiates GABA transmission by facilitating the opening of GABA-induced chloride channels. Etizolam is a specific antagonist at PAFR. It inhibits PAF-induced platelet aggregation by inhibiting PAF binding to the receptors located on the surface of platelets with an IC50 of 22nM.

The average elimination half life of etizolam following a single oral dose of 0.5mg is 3.4 hours but may be increased up to 17 hours depending on the rate of metabolism. The main metabolite α-hydroxyetizolam displays a longer elimination half life of 8.2 hours.

Biotransformation of etizolam is extensive and involves hydroxylation and conjugation. The main metabolite formed via 1'-hydroxylation is α-hydroxyetizolam which retains pharmacological activity comparable to that of the parent drug, indicating that the action of metabolites may contribute to the clinical effects of etizolam. CYP3A4 is predicted to be the main CYP enzyme responsible for mediating etizolam metabolism. CYP2C18 and CYP2C19 are also involved in the metabolic pathways.

Etizolam has known human metabolites that include alpha-Hydroxyetizolam and 7-(2-chlorophenyl)-4-ethyl-13-methyl-3-thia-1,8,11,12-tetrazatricyclo[8.3.0.02,6]trideca-2(6),4,7,10,12-pentaen-9-ol.

A traditional grouping of drugs said to have a soothing or calming effect on mood, thought, or behavior. Included here are the ANTI-ANXIETY AGENTS (minor tranquilizers), ANTIMANIC AGENTS, and the ANTIPSYCHOTIC AGENTS (major tranquilizers). These drugs act by different mechanisms and are used for different therapeutic purposes.

Etizolam is well absorbed from the intestines with a biological bioavailability of 93% following oral administration. After a single oral dosing of 0.5mg etizolam, it takes approximately 0.9 hours to reach the peak plasma concentration of 8.3 ng/mL.

In a rat study, the amounts of etizolam excreted was 30% in urine was 70% in feces, while the values in a mouse study were 40% in urine and 60% in feces.

Apparent distribution volume was 0.9 ± 0.2 L/kg following a single oral doing of 0.5mg etizolam.