Alpha-methylthiofentanyl

Year(s) and type of review / ECDD meetings
Drug Class
ECDD Recommendation
Inclusion in Schedule I and Schedule IV of the 1961 Convention on Narcotic Drugs
Recommendation (from TRS)
Substance identification
(CAS 103963-66-2), chemically N-[1-[l-methyl-2-(2-thienyl)ethyl]-4-piperidyl}propionanilide, is also known as NIH 10538 and MCV 4583. There is one chiral carbon atom in the molecule, so that two stereoisomers and one racemate are possible.

Similarity to known substances and effects on the CNS
Alpha-methylthiofentany/ has been classified pharmacologically as a relatively selective mu-type opioid-receptor agonist with a profile similar to that of fentanyl. Its analgesic potency in rodents is at least the same as that of fentanyl and 450-600 times that of morphine. Its analgesic effect has a rapid onset but a longer duration than that of fentanyl.

Dependence potential
Alpha-methylthiofentanyl substitutes completely for morphine in morphine-dependent withdrawn monkeys and is about 100 times more potent than morphine in this regard. No human studies are available concerning the dependence potential of alpha-methylthiofentanyl.

Actual abuse and or/evidence of likelihood of abuse
Alpha-methylthiofentanyl is one of the fentanyl analogues that have appeared in the illicit drug traffic since late 1979. It has been identified in drug seizures in the USA by a Drug Enforcement Administration laboratory, and clandestine production has been demonstrated.

Therapeutic usefulness
At present, alpha-methylthiofentanyl has no known therapeutic use.

Recommendation
The Committee found that there was

sufficient evidence to indicate that alpha-methylthiofentanyl is liable

to similar abuse to, and produces ill-effects similar to those seen

with, drugs in Schedule I of the Single Convention on Narcotic

Drugs, 1961, and that Convention as amended by the 1972 protocol.

The Committee rated the abuse liability of the substance as high. The public health and social problems associated with the substance are extremely serious and there is no known therapeutic use. Therefore, the Committee recommended that alpha-methylthiofentanyl be controlled in Schedules I and IV of the Single Convention on Narcotic Drugs, 1961, and that Conventioans amended by the 1972 protocol.