Current Scheduling Status
None
Year(s) and type of review / ECDD meetings
Drug Class
Recommendation (from TRS)
Substance identification
Methylpentynol (INN, CAS 77-75-8); chemical name: 3-methyl-1-pentyn-3-ol, is also known as meparfynol and oblivon. Methylpentynol has a carbamate (l-ethyl-l-methyl-2 propynyl
carbamate CAS 302-66-9) and a phthalate derivative (CAS 131-67-9). Methylpentynol has one asymmetric centre and exists as a racemate with two stereoisomers.
Similarity to known substances and effects on the CNS
As a mild sedative and hypnotic, methylpentynol is similar in activity to ethchlorvynol. In higher doses the effects resemble those of acute alcohol intoxication. Methylpentynol possesses no antispasmodic or analgesic activity. Large doses are reported to have no significant depressant effects upon respiration. Only a small percentage of the substance is eliminated unchanged in the urine. At low doses methylpentynol has a mild sedative activity and at higher doses a mild hypnotic one. Chronic intoxication may induce a decrease in vitality, slurred speech, giddiness, and stupor. Fatigue, insomnia, and psychotic symptoms have been reported with methylpentynol. Little information specific to the carbamate derivative is available
but the pharmacology and toxicology of this derivative appear similar to methylpentynol. No information specific to the phthalate derivative is available. This compound is only known for its anthelmintic activity.
Dependence potential
Controlled animal studies with methylpentynol show that it partially supports pentobarbital dependence and produces physical dependence. In drug discrimination studies, pigeons and rhesus monkeys did not discriminate methylpentynol as pentobarbital. The substance was self-administered by rhesus monkeys. The carbamate showed a similar profile. No controlled human dependence studies have been reported.
Actual abuse and or/evidence of likelihood of abuse
Chronic abuse has been. reported to produce symptoms of intoxication and lead to dependence formation with a withdrawal syndrome. Available information reveals. few demonstrable public health or social problems associated with methylpentynol or its carbamate derivative. Only a few cases of abuse have been reported in recent years. The substance or its carbamate derivative is under national controlin two countries and requires prescription in 10 of the 60 reporting countries. No case of illicit manufacture or illicit traffic has been reported.
No information is available for the methylpentynol phthalate derivative.
Therapeutic usefulness
Methylpentynol has been used as a sedative-hypnotic and in a variety of comination products. It is available on the market in ten of the 60 countries reporting. The therapeutic use of this drug has been largely replaced by more effective drugs. The Committee rated the therapeutic usefulness of methylpentynol as low.
Recommendation
On the basis of the available data concerning its pharmacological profile, dependence potential and actual abuse, the Committee rated the likelihood of abuse of methylpentynol and its derivatives as moderate. The degree of seriousness of the public health and social problems associated with the drug and its derivatives was found to be low as was its therapeutic usefulness. Despite its close relationship to ethchlorvynol, the Committee found that there was insufficient evidence that methylpentynol and its derivatives are being, or are likely to be, abused so as to constitute a public health and social problem warranting the placing of the substance and its. derivatives under international control. In the light of this assessment, the Committee did not recommend scheduling of the drug.
Methylpentynol (INN, CAS 77-75-8); chemical name: 3-methyl-1-pentyn-3-ol, is also known as meparfynol and oblivon. Methylpentynol has a carbamate (l-ethyl-l-methyl-2 propynyl
carbamate CAS 302-66-9) and a phthalate derivative (CAS 131-67-9). Methylpentynol has one asymmetric centre and exists as a racemate with two stereoisomers.
Similarity to known substances and effects on the CNS
As a mild sedative and hypnotic, methylpentynol is similar in activity to ethchlorvynol. In higher doses the effects resemble those of acute alcohol intoxication. Methylpentynol possesses no antispasmodic or analgesic activity. Large doses are reported to have no significant depressant effects upon respiration. Only a small percentage of the substance is eliminated unchanged in the urine. At low doses methylpentynol has a mild sedative activity and at higher doses a mild hypnotic one. Chronic intoxication may induce a decrease in vitality, slurred speech, giddiness, and stupor. Fatigue, insomnia, and psychotic symptoms have been reported with methylpentynol. Little information specific to the carbamate derivative is available
but the pharmacology and toxicology of this derivative appear similar to methylpentynol. No information specific to the phthalate derivative is available. This compound is only known for its anthelmintic activity.
Dependence potential
Controlled animal studies with methylpentynol show that it partially supports pentobarbital dependence and produces physical dependence. In drug discrimination studies, pigeons and rhesus monkeys did not discriminate methylpentynol as pentobarbital. The substance was self-administered by rhesus monkeys. The carbamate showed a similar profile. No controlled human dependence studies have been reported.
Actual abuse and or/evidence of likelihood of abuse
Chronic abuse has been. reported to produce symptoms of intoxication and lead to dependence formation with a withdrawal syndrome. Available information reveals. few demonstrable public health or social problems associated with methylpentynol or its carbamate derivative. Only a few cases of abuse have been reported in recent years. The substance or its carbamate derivative is under national controlin two countries and requires prescription in 10 of the 60 reporting countries. No case of illicit manufacture or illicit traffic has been reported.
No information is available for the methylpentynol phthalate derivative.
Therapeutic usefulness
Methylpentynol has been used as a sedative-hypnotic and in a variety of comination products. It is available on the market in ten of the 60 countries reporting. The therapeutic use of this drug has been largely replaced by more effective drugs. The Committee rated the therapeutic usefulness of methylpentynol as low.
Recommendation
On the basis of the available data concerning its pharmacological profile, dependence potential and actual abuse, the Committee rated the likelihood of abuse of methylpentynol and its derivatives as moderate. The degree of seriousness of the public health and social problems associated with the drug and its derivatives was found to be low as was its therapeutic usefulness. Despite its close relationship to ethchlorvynol, the Committee found that there was insufficient evidence that methylpentynol and its derivatives are being, or are likely to be, abused so as to constitute a public health and social problem warranting the placing of the substance and its. derivatives under international control. In the light of this assessment, the Committee did not recommend scheduling of the drug.
ECDD Recommendation
Scheduling/control not currently recommended
Link to full TRS
who_trs_761.pdf1.41 MB