A 55-year-old man is prescribed linezolid for vancomycin-resistant Enterococcus (VRE) bacteremia. He is also on sertraline for depression. The most serious potential drug interaction is:

• A QTc prolongation due to synergistic cardiac sodium channel blockade
• B Nephrotoxicity due to competition for organic anion transporter 3
• C Myelosuppression due to additive inhibition of mitochondrial protein synthesis
• D Serotonin syndrome due to linezolid's weak MAO-A inhibitory activity ✓

Explanation

Linezolid is a reversible, non-selective monoamine oxidase inhibitor (MAO-A and MAO-B). Combined with SSRIs (sertraline), it significantly elevates synaptic serotonin, causing serotonin syndrome manifest by hyperthermia, clonus, autonomic instability and altered consciousness. This is a recognised, potentially fatal interaction. Linezolid's myelosuppression is a concern with prolonged use but is not specifically enhanced by SSRIs.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.