ABSTRACT
BACKGROUND: Neutropenia is one of the most important dose-limiting toxicities of docetaxel. Docetaxel is metabolized by cytochrome P450 3A4 (CYP3A4). Clarithromycin, a potent inhibitor of CYP3A4, is occasionally used in combination with docetaxel. The aim of this study was to evaluate whether the risk of severe neutropenia induced by docetaxel was increased by concomitant administration of clarithromycin. METHODS: Patients with advanced lung cancer receiving docetaxel were identified from an electronic medical record system and divided into 2 groups: concomitant administration of clarithromycin and no concomitant administration of clarithromycin. The proportion of patients experiencing grade 4 neutropenia between the 2 groups was compared. Potential risk factors associated with grade 4 neutropenia were also examined using univariate and multivariate logistic regression analyses. RESULTS: One hundred and fifty-eight patients were analysed. Grade 4 neutropenia was more frequently detected in the patients receiving clarithromycin than in those not receiving the drug (63.2 vs. 35.3%; p = 0.025). Multivariate analysis showed that co-administration of clarithromycin [odds ratio (OR) 4.98; p = 0.004], pre-treatment absolute neutrophil count (OR 2.62; p = 0.011) and female gender (OR 2.75; p = 0.029) resulted in an increase in the incidence of grade 4 neutropenia. CONCLUSIONS: This study shows that concomitant administration of clarithromycin potentiated docetaxel-induced myelosuppression.