Which antiepileptic drug is known to accumulate in infants due to slower metabolism?

• A. Lamotrigine
• B. Levetiracetam
• C. Carbamazepine
• D. Valproate

Answer: (A)

Infants have immature drug-metabolizing enzymes, so how a drug is cleared can change a lot with age. Lamotrigine is cleared mainly through hepatic glucuronidation. In neonates, UDP-glucuronosyltransferase enzymes are underdeveloped, so lamotrigine is cleared more slowly and can accumulate to higher plasma levels for a given dose. This makes lamotrigine prone to accumulation in infants unless dosing is carefully adjusted.

Levetiracetam is mostly eliminated by the kidneys, so its clearance relates more to renal maturity than to glucuronidation. Carbamazepine relies on hepatic metabolism and autoinduction, which complicates dosing but isn’t the classic case of immature glucuronidation driving accumulation. Valproate is also hepatically metabolized, but the specific issue of slow glucuronidation in infants points most clearly to lamotrigine.