Recommendation (from TRS)
ECDD Technical summary
Substance identification
Carisoprodol (IUPAC name: 2-[(carbamoyloxy)methyl]-2-methylpentyl(1-methylethyl)carbamate) is a
centrally-acting skeletal muscle relaxant sold as a single-ingredient preparation and in combination
products. Carisoprodol is available as a pharmaceutical product in tablet form, has been detected in
falsified pharmaceuticals and is also found as a white powder.
WHO review history
Carisoprodol was pre-reviewed at the 32nd ECDD meeting in 2000. The Committee did not
recommend critical review of carisoprodol at that time, noting that sporadic nonmedical use of
carisoprodol was not a new phenomenon and there was no indication of significantly increasing
nonmedical use. A new pre-review was initiated in 2023 after information received from an
international agency that suggested a significant increase in the reported number of trafficking cases
and seizures involving carisoprodol.
Similarity to known substances and effects on the central nervous system
Carisoprodol is an analogue of meprobamate and has effects similar to those of other central nervous
system depressants such as meprobamate, pentobarbital, diazepam and chlordiazepoxide that are
listed under schedules III and IV of the Convention on Psychotropic Substances of 1971.
Meprobamate is also a metabolite of carisoprodol. Although its exact mechanism of action is not
known, the therapeutic effects of carisoprodol appear to be due to modulation of GABAA receptors
similar to the action of barbiturates. The sedative effects of carisoprodol can be potentiated when it is
combined with benzodiazepines, opioids or alcohol.
Dependence potential
Tolerance and withdrawal have been documented in experimental animals, and the potential for
dependence on carisoprodol is considered to be similar to that of barbiturates and benzodiazepines.
Tolerance, withdrawal and craving have been documented in humans, and increasing numbers of
cases of carisoprodol dependence have been documented in pharmacovigilance reporting systems.
Actual abuse and/or evidence of likelihood of abuse
In animal models indicative of abuse liability, the effects of carisoprodol were similar to those of
pentobarbital, chlordiazepoxide and meprobamate in a dose-dependent manner. In humans,
carisoprodol produces central nervous system depressant effects, including drowsiness, sedation,
confusion and coma.
Public health harm associated with use of carisoprodol has included cases of driving under the
influence of the drug.
Nonmedical use of carisoprodol is widely documented in multiple countries and regions, including in
combination with opioids and/or benzodiazepines. The incidence of poisoning and other public health
harm has been reported to have decreased in some countries after increased restrictions on
carisoprodol prescription or removal of the drug from the market.
Therapeutic use
Carisoprodol is a centrally acting muscle relaxant used in some countries in the short term as an
adjunct in symptomatic treatment of acute musculoskeletal disorders associated with painful muscle
spasms. It is not on the 2023 WHO Essential Medicines List or the WHO Essential Medicines List for
Children. It has been withdrawn from use in some countries because of concern about increased rates
of diversion, nonmedical use, dependence, intoxication and psychomotor impairment.
Rationale and recommendation
The increasing evidence of misuse and abuse of carisoprodol in a number of countries is a growing
cause for concern. Carisoprodol has been shown to produce a state of dependence and central
nervous system depression. It has only limited medical use.
The Committee recommended that carisoprodol be subject to a future critical review.