(British Approved Name, rINN)
International Nonproprietary Names (INNs) in main languages (French, Latin, and Spanish):
Pharmacopoeias. In US.
The United States Pharmacopeia 31, 2008 (Ethchlorvynol). A colourless to yellow, slightly viscous liquid having a characteristic pungent odour. It darkens on exposure to air and light. Immiscible with water miscible with most organic solvents. Store in airtight containers of glass or polyethylene, using polyethylene-lined closures. Protect from light.
Dependence and Withdrawal
Prolonged use of ethchlorvynol may lead to dependence similar to that with barbiturates (see Amobarbital).
Adverse effects of ethchlorvynol include gastrointestinal disturbances, dizziness, headache, unwanted sedation and other symptoms of CNS depression such as ataxia, facial numbness, blurred vision, and hypotension. Hypersensitivity reactions include skin rashes, urticaria, and occasionally, thrombocytopenia and chole-static jaundice. Idiosyncratic reactions include excitement, severe muscular weakness, and syncope without marked hypotension.
Acute overdosage is characterised by prolonged deep coma, respiratory depression, hypothermia, hypotension, and relative bradycardia. Pancytopenia and nystagmus have occurred. Pulmonary oedema has followed abuse by intravenous injection.
Treatment of Adverse Effects
Treatment is as for barbiturate overdose (see Amobarbital). Haemoperfusion may be of value in the treatment of severe poisoning with ethchlorvynol.
Ethchlorvynol should be used with caution in patients with hepatic or renal impairment or with depression, in patients with severe uncontrolled pain, and, as with all sedatives, in those with impaired respiratory function. It may cause drowsiness affected patients should not drive or operate machinery. Excessively rapid absorption of ethchlorvynol in some patients has been reported to produce giddiness and ataxia this may be reduced by giving it with food.
Porphyria. Ethchlorvynol has been associated with acute attacks of porphyria and is considered unsafe in porphyric patients.
The effect of ethchlorvynol may be enhanced by alcohol, barbiturates, and other CNS depressants. Ethchlorvynol has been reported to decrease the effects of coumarin anticoagulants.
Tricyclic antidepressants. Transient delirium has been reported from the use of ethchlorvynol with amitriptyline but details of such an interaction do not appear to have been published in the literature.
Ethchlorvynol is readily absorbed from the gastrointestinal tract, peak plasma concentrations usually occurring within 2 hours of ingestion. It is widely distributed in body tissues and is extensively metabolised in the liver, and possibly to some extent in the kidneys. It has a biphasic plasma half-life with a rapid initial phase and a terminal phase reported to last from 10 to 20 hours. Ethchlorvynol is excreted mainly in the urine as metabolites and their conjugates. Ethchlorvynol crosses the placenta.
Uses and Administration
Ethchlorvynol is a hypnotic and sedative with some anticonvulsant and muscle relaxant properties. It is given for the short-term management of insomnia but has been largely superseded by other drugs. Use for periods greater than one week is not recommended. The usual oral hypnotic dose is 500 mg at night but doses ranging from 200 mg to 1 g have been given. Taking doses with food has been recommended — see Precautions, above.
The United States Pharmacopeia 31, 2008: Ethchlorvynol Capsules