Thiamylal sodium

Current Scheduling Status
Year(s) and type of review / ECDD meetings
Drug Class

Recommendation (from TRS)

Substance identification
Thiamylal- sodium (CAS-337-47-3), chemically 5-allyl-5-(1-methylbutyl)-2-thiobarbituric acid sodium, is also known as thiaseconal. It is a racemic mixture.

Similarity to known substances and effects on the CNS
Thiamylal has been classified pharmacologically as an ultrashort acting barbiturate used as an intravenous anaesthetic agent. Barbiturates of this type have not been scheduled. Dose-related drowsiness, vertigo, confusion, and incoordination do occur. The drug, like other barbiturates, is metabolized by hepatic microsomal enzymes and stimulates the production of these enzymes. Like the. other short-acting barbiturates, thiamylal sodium produces a dose-related depression of the central nervous system, ranging from mild sedation to general anaesthesia and coma. Tolerance, both natural and functional, can occur. Cross-tolerance may occur to other barbiturates, ethanol, and other sedative-hypnotic drugs.

Dependence potential
The substance has been found in one experiment to induce selfadministration by the intravenous route in rhesus monkeys with cross-reinforcement to other barbiturates. No information is available on the ability of: thiamylal to induce physical dependence in animals or in man.

Actual abuse and or/evidence of likelihood of abuse
There are no reports of abuse, and only the United States of America has reported a very small number of seizures. Six countries have reported that the substance is under national control.

Therapeutic usefulness
Thiamylal is used as an intravenous anaesthetic. It is available or registered in eight countries mainly for hospital use, although it is used much less extensively than thiopental (see section 3.29). The Committee rated the therapeutic usefulness of thiamylal as an intravenous anaesthetic agent as high.

The Committee found that there was: insufficient evidence that thiamylal sodium is. being, or is likely to be, abused so as to constitute a public health and social problem warranting the placing of the substance under international control. On the basis of the data concerning its pharmacological profile, dependence potential, and actual abuse, the Committee rated the

likelihood of abuse of thiamylal sodium as moderate. The degree of the public health and social problems associated with the drug was found to be low and its therapeutic usefulness high. In the light of this assessment, the Committee recommended against scheduling of the drug.

ECDD Recommendation

Scheduling/control not currently recommended