Methsuximide

Methsuximide is an anticonvulsant in the succinimide class used to treat absence seizures. It is structurally and pharmacologically related to ethosuximide and is sometimes employed when ethosuximide is ineffective, not tolerated, or in specific seizure-management regimens.

Mechanism of action: Methsuximide is thought to reduce neuronal excitability associated with absence seizures by inhibiting T-type calcium channels in thalamic neurons, thereby diminishing the abnormal thalamocortical rhythms underlying these seizures.

Administration and pharmacokinetics: The drug is administered orally and undergoes hepatic metabolism with renal excretion of metabolites. It typically requires regular dosing, with adjustments based on response and tolerance.

Adverse effects: Common adverse effects include gastrointestinal upset, drowsiness, dizziness, and headaches. Weight loss, hiccups, and rash can occur. Rare but serious effects may include hypersensitivity reactions or blood dyscrasias; patients should be monitored clinically.

Interactions and safety: Methsuximide may interact with other anticonvulsants and central nervous system depressants, affecting efficacy or tolerability. As with other antiepileptics, use should be guided by clinicians with consideration of comorbidities and concurrent medications.

History and status: Methsuximide, marketed historically under brand names such as Celontin, is an older anticonvulsant. It is less commonly used today, with ethosuximide and other agents preferred for many patients, though it may be selected in certain circumstances.