Drug Interactions between diltiazem and taletrectinib

Consumer information for this interaction is not currently available.

GENERALLY AVOID: Coadministration with grapefruit juice may increase the plasma concentrations of taletrectinib. The proposed mechanism for the interaction is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. Inhibition of hepatic CYP450 3A4 may also contribute. The interaction has not been studied with grapefruit juice but has been reported for other CYP450 3A4 inhibitors. In a clinical study, taletrectinib peak plasma concentration (Cmax) increased by 1.8-fold and systemic exposure (AUC) increased by 3.3-fold following concomitant administration of itraconazole, a potent CYP450 3A inhibitor. According to the product labeling, administration of taletrectinib with a moderate CYP450 3A inhibitor is predicted to increase taletrectinib Cmax and AUC by up to 1.5- and 2.6-fold, respectively. Increased exposure to taletrectinib may increase the risk and/or severity of adverse effects such as hepatotoxicity with liver enzyme elevations, lung toxicities, QT prolongation, hyperuricemia, myalgia with creatine phosphokinase elevation, and skeletal fractures.

ADJUST DOSING INTERVAL: Coadministration with high-fat food (1000 calories, 50% fat) increased taletrectinib Cmax and AUC by 1.5-fold, and the predicted increase in the QTc interval is 20.5 msec.

MANAGEMENT: The manufacturer recommends avoiding food or drink containing grapefruit during treatment with taletrectinib. In addition, taletrectinib should be administered on an empty stomach at about the same time each day, at least 2 hours before or 2 hours after food intake.

Alcohol can lower your blood pressure and add to the effects of dilTIAZem. You may experience dizziness, lightheadedness, fainting, or a rapid heartbeat if you drink alcohol with dilTIAZem, especially when you first start taking the medication or just after a dose increase. Grapefruit juice may also increase the effects of dilTIAZem in some people by increasing its levels in the blood. You may want to limit alcohol intake and avoid excessive consumption of grapefruit and grapefruit juice during treatment with dilTIAZem. However, if you have been regularly consuming grapefruit or grapefruit juice with dilTIAZem, do not alter the amounts of these products in your diet without first talking to your doctor or other healthcare professional. Contact your doctor if your condition changes or you experience increased side effects of dilTIAZem such as headache, irregular heartbeat, swelling, unexplained weight gain, or chest pain. Orange juice is not expected to interact.

Using dilTIAZem together with multivitamin with minerals can decrease the effects of dilTIAZem. Talk with your doctor before using dilTIAZem and multivitamin with minerals together. You may need a dose adjustment or need your blood pressure checked more often if you take both medications. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.