Which of the following antiepileptic drugs is associated with a DOSE-DEPENDENT worsening of tremor and pancreatitis, and requires monitoring of serum levels due to non-linear pharmacokinetics?
- A Valproic acid ✓
- B Levetiracetam
- C Lamotrigine
- D Topiramate
Correct answer: A. Valproic acid
Explanation
Valproic acid (valproate) causes essential tremor as a dose-dependent side effect, pancreatitis (idiosyncratic but rare), hepatotoxicity (particularly in children under 2 on polytherapy), and teratogenicity (neural tube defects). Its pharmacokinetics are non-linear at higher doses due to saturation of plasma protein binding. Levetiracetam has linear kinetics; lamotrigine's main concern is Stevens-Johnson syndrome with rapid titration; topiramate causes cognitive slowing and renal stones.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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