Vigabatrin was withdrawn from general use despite good efficacy in infantile spasms and refractory focal seizures. The limiting toxicity and its mechanistic basis are:

• A Aplastic anemia due to bone marrow progenitor apoptosis
• B Progressive multifocal leukoencephalopathy from JC virus reactivation
• C Concentric visual field constriction caused by retinal ganglion cell and photoreceptor toxicity ✓
• D Fatal hepatotoxicity from mitochondrial beta-oxidation failure

Explanation

Vigabatrin irreversibly inhibits GABA transaminase, raising CNS GABA, but up to one third of patients develop bilateral concentric constriction of visual fields from cumulative retinal toxicity. Baseline and serial visual field testing or ophthalmologic assessment is mandatory where the drug is used. Aplastic anemia limits felbamate, and fatal hepatotoxicity with microvesicular steatosis is the classic idiosyncratic risk of valproate.

Reference: Katzung Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.