A patient receiving second-line therapy for MDR-TB develops paranoia, hallucinations and seizures. The drug responsible is a structural analogue of D-alanine that blocks incorporation of D-alanine into the bacterial cell wall peptidoglycan. Its major limiting toxicity is:
- A Central nervous system toxicity including psychosis and seizures ✓
- B Hepatotoxicity
- C Optic neuritis
- D QT prolongation
Correct answer: A. Central nervous system toxicity including psychosis and seizures
Explanation
The drug is cycloserine, a D-alanine analogue that inhibits D-alanine:D-alanine ligase and alanine racemase, blocking peptidoglycan synthesis. It penetrates the CSF well, which explains its use in TB meningitis, but this same property underlies its principal toxicity: headache, psychosis, depression and seizures. Pyridoxine is given to reduce neurotoxicity. Epilepsy and psychiatric illness are relative contraindications.
Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 13th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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