Current Scheduling Status
Year(s) and type of review / ECDD meetings
Drug Class
ECDD Recommendation
Scheduling/control not currently recommended
Recommendation (from TRS)
Substance identification
Paraldehyde (INN, CAS 123-63-7), chemically 2,4,6-trimethyl-strioxane, is also known as paracetaldehyde, paraidehydum or paral. It has two stereoisomeric forms (cis and trans),

Similarity to known substances and effects on the CNS
Paraldehyde has been classified as a non-barbiturate sedative-hypnotic. In addition to its sedative and hypnotic effects, it also has some analgesic and anticonvulsant properties. Overdose of the drug produces headache, tachycardia, hypotonia, nausea and vomiting as well as symptoms similar to those of- alcohol intoxication. Chronic paraldehyde use may result in chronic poisoning characterized by hallucinations, delusions, impairment of memory and intellect, anxiety, impaired speech, unsteady gait, paraesthesias and tremors. It is metabolized in the liver to acetaldehyde, which is then metabolized to carbon dioxide and water. Some of the ingested paraldehyde is exhaled.

Dependence potential
In dogs, acute tolerance to paraldehyde and cross-tolerance between paraldehyde and barbiturates can occur. In humans, in the case of chronic intoxication, an alcohol-like physical dependence is observed, with withdrawal signs on cessation of use. An unpleasant taste and associated burning sensation probably tend to prevent paraldehyde abuse. Notwithstanding these unpleasant effects, psychological and physical dependence on the drug has been observed after prolonged and excessive use.

Actual abuse and or/evidence of likelihood of abuse
In the past, paraldehyde was abused by many former alcohol abusers, particularly when they were abstaining completely from alcohol. No significant public health problems resulting from such abuse have ever been reported.

Therapeutic usefulness
Although paraldehyde has been used for the treatment of alcoholic delirium tremens, status epilepticus, excitement states in psychiatry, eclampsia and tetanus, it is currently a drug of limited therapeutic usefulness and has been replaced by other drugs in clinical practice in many countries.

On the basis of the available data concerning its pharmacological profile, dependence potential and actual abuse, the Committee rated the likelihood of abuse of paraldehyde as moderate and the therapeutic usefulness as low. Very few public health and social problems have been found to be associated with the substance, and the Committee considered. that they were not serious enough to warrant placing it under international control. The Committee did not recommend scheduling of paraldehyde.