section name header

Interacting Drugs

OBJECT DRUGS

Calcium Channel Blockers:

PRECIPITANT DRUGS

Antimicrobials:


Comment:

Calcium channel blockers (CCBs) are metabolized by CYP3A4, so CYP3A4 inhibitors may substantially increase their serum concentrations, thus increasing the risk of hypotension and other adverse cardiovascular effects. Not all combinations of CCBs and CYP3A4 inhibitors have been studied; assume they interact until proven otherwise. Note, however, that the magnitude of interaction can vary considerably depending on the CCB involved. For example, felodipine undergoes extensive first pass metabolism by CYP3A4 and is markedly affected by CYP3A4 inhibition, while amlodipine undergoes considerably less first pass metabolism by CYP3A4 and is much less affected by CYP3A4 inhibition. Short-term use of an azole antifungal (1-2 days) is unlikely to result in a clinically important interaction. Erythromycin and clarithromycin may also have intrinsic effects on cardiac conduction that may increase the risk of hypotension.


Class 3: Assess Risk & Take Action if Necessary