Drug Interactions between amoxicillin / clarithromycin / vonoprazan and cobimetinib

GENERALLY AVOID: Coadministration with potent inhibitors of CYP450 3A4 may significantly increase the plasma concentrations of cobimetinib, which is primarily metabolized by the isoenzyme. In 15 healthy volunteers given a single 10 mg dose of cobimetinib with the potent CYP450 3A4 inhibitor itraconazole (200 mg once daily for 14 days), mean cobimetinib peak plasma concentration (Cmax) and systemic exposure (AUC) increased by 3.2- and 6.7-fold, respectively, compared to cobimetinib administered alone. The risk and/or severity of adverse effects such as diarrhea, nausea, vomiting, stomatitis, hemorrhage, cardiomyopathy, rash, photosensitivity, retinopathy, retinal vein occlusion, liver enzyme abnormalities, and rhabdomyolysis may be increased.

MANAGEMENT: Concomitant use of cobimetinib with potent CYP450 3A4 inhibitors should generally be avoided. Some authorities recommend avoiding concomitant use of cobimetinib during and for 2 weeks after treatment with itraconazole.

MONITOR: Coadministration with inhibitors of CYP450 3A4 and/or P-glycoprotein (P-gp) may increase the plasma concentrations of cobimetinib, which is a substrate of both the isoenzyme and the efflux transporter. In 15 healthy volunteers given a single 10 mg dose of cobimetinib with the potent CYP450 3A4 and P-gp inhibitor itraconazole (200 mg once daily for 14 days), mean cobimetinib peak plasma concentration (Cmax) and systemic exposure (AUC) increased by 3.2- and 6.7-fold, respectively, compared to cobimetinib administered alone. Simulations using physiologically-based pharmacokinetic (PBPK) models suggest that steady-state concentrations of cobimetinib given at a reduced dose of 20 mg with short-term (less than 14 days) use of a moderate CYP450 3A4 inhibitor would be similar to steady-state concentrations observed following a 60 mg dose given alone.

MANAGEMENT: Caution is advised when cobimetinib is prescribed with CYP450 3A4 and/or P-gp inhibitors. Patients should be monitored for adverse effects such as diarrhea, nausea, vomiting, stomatitis, hemorrhage, cardiomyopathy, rash, photosensitivity, retinopathy, retinal vein occlusion, liver enzyme abnormalities and rhabdomyolysis, and the cobimetinib dosage adjusted accordingly or treatment discontinued as necessary.

Although some in vitro data indicate synergism between macrolide antibiotics and penicillins, other in vitro data indicate antagonism. When these drugs are given together, neither has predictable therapeutic efficacy. Data are available for erythromycin, although theoretically this interaction could occur with any macrolide. Except for monitoring of the effectiveness of antibiotic therapy, no special precautions appear to be necessary.