Methocarbamol (MCB)

Methocarbamol is a central muscle relaxant used to treat skeletal muscle spasms. Methocarbamol produces its clinical effects through agonism of the GABAA receptor, resulting in an exaggerated effect of gamma-aminobutyric acid (GABA) which occurs naturally in the brain. Activation of the GABA receptor increases the amount of chloride ions that pass through the chloride channel of cells, resulting in a depressant effect by reducing the cells action potential. This mechanism is very similar to that of barbiturates, benzodiazepines, z-drugs, alcohol, and GABA analogues such as GHB. Most GABAergics require GABA as a co-factor in order to activate the chloride channel, however methocarbamol can activate the chloride channel even in the absence of GABA; this ability is called direct agonism and is relatively rare among GABAergic drugs, being shared only by other carbamate derivatives and a handful of other substances.