Drug Interaction Report

Coadministration with CYP450 3A4 inhibitors is not expected to have clinically significant effects on the plasma concentrations of cabazitaxel, a narrow therapeutic index drug, which is primarily metabolized via the isoenzyme. A drug interaction study in patients with advanced cancers (n=13), revealed repeated administration of the moderate CYP450 3A4 inhibitor aprepitant (125 mg or 80 mg once daily) did not modify the exposure to cabazitaxel (15 mg/m2 intravenous). Clinical data with less potent CYP450 3A4 inhibitors are not available.

MONITOR: Due to their gastrointestinal pharmacologic effects, somatostatin analogs (e.g., octreotide, lanreotide) may variously affect the absorption of dietary nutrients and concomitantly administered oral medications. Somatostatin analogs have been shown to prolong gastrointestinal transit time and inhibit intestinal absorption of some nutrients such as fat. Clinical data are limited, however. In case reports, octreotide has been reported to reduce the relative bioavailability of cyclosporine. Transplant rejection and significant reductions in cyclosporine levels, sometimes to undetectable levels, have been reported in association with the interaction. Vitamin K absorption was not affected when concomitantly administered with lanreotide according to the manufacturer.

MANAGEMENT: Clinicians should be aware of the potential for altered absorption of concomitantly administered oral medications during treatment with somatostatin analogs. Blood levels and clinical response should be monitored, particularly for drugs that have a narrow therapeutic index, and the dosages adjusted as necessary.