Commonly known by the brand names Soma and Dolaren; Carisoprodol is a centrally acting depressant-type drug known for its skeletal muscle relaxant properties. Its pharmacology has not been well defined; but being an closely related analogue of the sedative drug meprobamate (which is also its main metabolite), it is believed to have central GABAergic properties similar to those of meprobamate - which modulates GABA-a receptor activity in areas such as the thalamus, limbic system and spinal cord. Aside from general sedative-hypnotic properties (similar to benzodiazepines or barbiturates), carisoprodol and its major metabolite produce skeletal muscle relaxation, specifically by suppressing neuronal activity in the reticular formulation and spinal cord.
Carisoprodol is licensed for use in the US as a muscle relaxant and adjunct analgesic, available alone or as a compound analgesic + muscle relaxant. Within the last year, the drug has been listed by the DEA in schedule V of US drug law, effective on January 1st of this year (2012). Up until now it had managed to evade this classification. The drug is sold as a single entity product under the trade name Soma, in combination with aspirin, or in combination with a weak opioid such as codeine (trade name "Soma compound w/ codeine").
Meprobamate is a major metabolite of carisoprodol. It is a CNS depressant with sedative-hypnotic, anticonvulsant, and anxiolytic properties. Exhibits barbiturate-like modulatory effects on the GABA-a receptor, and therefore produces many of the same effects. Meprobamate also acts as an adenosine reuptake inhibitor. This drug falls under the purview of US drug law; it is a schedule IV controlled substance.