Linezolid is used as a reserve drug for MRSA and VRE infections. Its most serious dose-limiting adverse effect with prolonged use (>2 weeks) is:

• A Nephrotoxicity due to proximal tubular accumulation
• B Hepatotoxicity from idiosyncratic metabolite formation
• C QTc prolongation with risk of torsades de pointes
• D Myelosuppression, particularly thrombocytopenia, due to inhibition of mitochondrial protein synthesis in hematopoietic cells ✓

Explanation

Linezolid inhibits the 50S ribosomal subunit by a unique mechanism (blocking initiation complex formation) and, because it also inhibits mammalian mitochondrial ribosomes (which are 70S-like), prolonged use causes mitochondrial protein synthesis inhibition in rapidly dividing cells, particularly platelets and their precursors. This manifests as reversible thrombocytopenia and, less commonly, anemia and peripheral/optic neuropathy. It is not primarily nephrotoxic, hepatotoxic, or a significant cause of QTc prolongation.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.