Drug Interactions
A study was conducted in 30 patients with advanced breast cancer to determine the potential for drug-drug-interactions between Taxotere® (docetaxel) (75 mg/m2), doxorubicin (50 mg/m2), and cyclophosphamide (500 mg/m2) when administered in combination.1
The coadministration of Taxotere® had no effect on the pharmacokinetics of doxorubicin and cyclophosphamide when the three drugs were given in combination compared to coadministration of doxorubicin and cyclophosphamide only. In addition, doxorubicin and cyclophosphamide had no effect on Taxotere® plasma clearance when the three drugs were given in combination compared to historical data for Taxotere® monotherapy.1
In vitro studies showed that Taxotere® is about 94% protein bound, mainly to 1-acid glycoprotein, albumin, and lipoproteins. In three cancer patients, the in vitro binding to plasma proteins was found to be approximately 97%. Dexamethasone does not affect the protein binding of Taxotere.1
In vitro drug interaction studies suggest that Taxotere® is metabolized by the CYP3A4 isoenzyme, and its metabolism can be inhibited by CYP3A4 inhibitors, such as the following:
- Ketoconazole
- Erythromycin
- Troleandomycin
- Nifedipine1
Based on in vitro findings, it is likely that CYP3A4 inhibitors and/or substrates may lead to substantial increases in Taxotere® blood concentrations. No clinical studies have been performed to evaluate this finding.1
References
- Taxotere® Prescribing Information. Bridgewater, NJ: sanofi-aventis U.S. LLC; November 2007.