Adults

Initial dose 250 mg twice daily, increasing to 500 mg twice daily after 2 weeks. Dosage can be increased by 250 mg twice daily increments every 2 weeks to a maximum of 1500 mg twice daily.

Elderly

No specific dosage adjustment based solely on age, but renal function should be assessed, and dosage adjusted accordingly.

Renal_impairment

Dosage reduction is required. For moderate renal impairment (CrCl 30-50 mL/min), initial dose 250 mg twice daily, maximum 750 mg twice daily. For severe renal impairment (CrCl < 30 mL/min), initial dose 250 mg once daily, maximum 500 mg once daily.

Onset

Within hours of the first dose, full therapeutic effect may take several days of consistent dosing.

Excretion

Mainly (95%) excreted via the kidneys, with approximately 66% excreted as unchanged drug and 24% as the inactive carboxylic acid metabolite.

Half life

Approximately 6-8 hours in adults and 4-5 hours in children. It increases with impaired renal function.

Absorption

Rapid and almost complete absorption after oral administration, with peak plasma concentrations occurring within 1 hour. Bioavailability is nearly 100%.

Metabolism

Minimal metabolism in humans (less than 3%). It is primarily hydrolyzed by enzymes to an inactive carboxylic acid derivative. No significant involvement of hepatic cytochrome P450 isoenzymes.

Alcohol and CNS depressants

Concurrent use with alcohol or other CNS depressants may increase CNS side effects such as drowsiness and dizziness.

No significant pharmacokinetic interactions

Levetiracetam does not appear to interact with other antiepileptic drugs (e.g., carbamazepine, phenytoin, valproate) or oral contraceptives in a clinically significant way.