Increased plasma concentration of quetiapine induced by clarithromycin
Clinical Pharmacy Office, Linyi Municipal Mental Health Center, Shandong Province, Linyi 276005, China; Department of Psychiatry, Linyi Municipal Mental Health Center, Shandong Province, Linyi 276005, China
Abstract：A 29-year-old male patient was treated with quetiapine fumarate (maintenance dose: 0.2 g twice daily) and magnesium valproate sustained release tablets (maintenance dose: 0.5 g twice daily) for bipolar affective disorder. After 9 days of treatments, the patient′s psychiatric symptoms were improved, no adverse reactions occurred, and plasma concentration of quetiapine was 379-μg/L. Clarithromycin 0.25 g orally twice daily was added because of concurrent suppurative otitis media. The next morning, the patient developed lethargy and the blood concentration of quetiapine increased to 614-μg/L, which was considered to be caused by the interaction of clarithromycin and quetiapine. Quetiapine fumarate and clarithromycin were discontinued and intravenous fluids were given to accelerate drug metabolism rate. On the 2nd day, the patient′s lethargy disappeared. Quetiapine fumarate at the original dose was given, magnesium valproate sustained-release tablets were continued, and the antimicrobial drug was switched to cefdinir capsules 0.1 g orally thrice daily. Then the symptoms above-mentioned did not recur.
