A convulsant is a drug which induces convulsions and/or epileptic seizures, the opposite of an anticonvulsant. These drugs generally act as stimulants at low doses, but are not used for this purpose due to the risk of convulsions and consequent excitotoxicity. Most convulsants are antagonists (or inverse agonists) at either the GABAA or glycine receptors, or ionotropic glutamate receptor agonists. Many other drugs may cause convulsions as a side effect at high doses (e.g. bupropion, tramadol, pethidine, dextropropoxyphene, clomipramine) but only drugs whose primary action is to cause convulsions are known as convulsants. Nerve agents such as sarin which were developed as chemical weapons, produce convulsions as a major part of their toxidrome, but also produce a number of other effects in the body and are usually classified separately.
Some convulsants such as pentetrazol and flurothyl were previously used in shock therapy in psychiatric medicine, as an alternative to electroconvulsive therapy. Others such as strychnine and tetramethylenedisulfotetramine are used as poisons for exterminating pests. Bemegride and flumazenil are used to treat drug overdoses (of barbiturates and benzodiazepines respectively), but may cause convulsions if the dose is too high. Convulsants are also widely used in scientific research, for instance in the testing of new anticonvulsant drugs. Convulsions are induced in captive animals, then high doses of anticonvulsant drugs are administered.
- GABAA receptor antagonists, inverse agonists or negative allosteric modulators
- GABA synthesis inhibitors
- Glycine receptor antagonists
- RU-5135 (also GABA antagonist)
- Ionotropic glutamate receptor agonists
- Acetylcholine receptor agonists
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