A patient with extensively drug-resistant tuberculosis has been on linezolid 600 mg daily for 10 weeks and develops easy bruising and a platelet count of 60,000 per microliter, along with new numbness of the feet. What is the appropriate action and rationale?
- A Continue the same dose since these effects are unrelated to linezolid
- B Reduce the dose to 300 mg daily or interrupt therapy, because hematologic and neurologic toxicity are time and dose dependent ✓
- C Add pyridoxine and continue unchanged, as these effects reverse spontaneously
- D Switch immediately to capreomycin, since linezolid has no role beyond 2 weeks
Correct answer: B. Reduce the dose to 300 mg daily or interrupt therapy, because hematologic and neurologic toxicity are time and dose dependent
Explanation
Linezolid inhibits mitochondrial protein synthesis as well as bacterial ribosomes, producing dose- and duration-dependent myelosuppression (especially thrombocytopenia), peripheral and optic neuropathy, and lactic acidosis. Toxicity risk rises sharply with use beyond about two weeks. In MDR-TB regimens the dose is therefore reduced to 300 mg daily or interrupted when toxicity appears. Pyridoxine does not prevent these mitochondrial effects reliably.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.