OBJECT DRUGS

Vinca Alkaloids:

• Vinblastine (Velban)
• Vincristine (Oncovin)
• Vinorelbine (Navelbine)

PRECIPITANT DRUGS

Calcium Channel Blockers:

• Diltiazem (Cardizem, etc.)
• Nicardipine (Cardene, etc.)
• Nifedipine (Procardia, etc.)
• Verapamil (Isoptin, etc.)

Comment:

Vinca alkaloids appear to be metabolized by CYP3A4 and reports have described severe toxicity in patients receiving CYP3A4 inhibitors such as verapamil. P-glycoprotein inhibition may also be involved in these interactions.

Class 2: Use Only if Benefit Felt to Outweigh Risk

• Use Alternative: Use an alternative to the enzyme inhibitor if possible.
• Calcium channel blockers: Calcium channel blockers other than diltiazem, nicardipine, nifedipine, and verapamil are unlikely to inhibit the metabolism of vinca alkaloids.
• Monitor: Monitor for toxicity from vincristine (primarily peripheral neuropathy symptoms: paresthesias, neuritic pain, muscle pain, constipation sometimes progressing to paralytic ileus) or vinblastine and vinorelbine (primarily bone marrow suppression).