The pharmacology of antimyoclonic drugs.

The molecular mechanisms of myoclonus are unknown. Drugs used in the symptomatic treatment of myoclonus were developed for other indications, such as epilepsy. Antimyoclonic drugs are not a single family of compounds but rather constitute a heterogeneous group of agents that act at various sites along the metabolic pathway of neurotransmitters or as receptor agonists or antagonists. For some drugs, the mechanism of antimyoclonic action is obscure despite many known actions. Myoclonus is affected by manipulation of more than one neurotransmitter system, and the neurotransmitters most linked to myoclonus are gamma-aminobutyric acid (GABA), glutamate, glycine, and serotonin. This is a review of the pharmacology of drugs acting on those neurotransmitters that are known or potential antimyoclonic drugs. A time of continuing advances in molecular biology and drug development is propitious for the pharmacotherapy of disorders that historically have been so refractory to conventional drug treatment.