A patient receiving IV linezolid for MRSA nosocomial pneumonia has baseline hemoglobin 13 g/dL and platelet count 240,000/mm3. Beyond which cumulative duration of therapy does weekly complete blood count monitoring become mandatory because of the principal dose-related hematologic toxicity?
- A More than 3 days
- B More than 14 days ✓
- C More than 7 days
- D More than 28 days
Correct answer: B. More than 14 days
Explanation
Linezolid causes reversible myelosuppression, most commonly thrombocytopenia and anemia, which is time and dose dependent and appears predominantly when therapy exceeds 14 days. Product labeling mandates weekly CBC monitoring in patients who receive the drug beyond two weeks, in those with preexisting cytopenias, or with severe renal impairment. Shorter courses carry minimal hematologic risk, so options A and C are too conservative.
Reference: Katzung Basic and Clinical Pharmacology, 16th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.