OBJECT DRUGS
Calcium Channel Blockers:
- Amlodipine (Norvasc)
- Bepridil (Vascor)
- Diltiazem (Cardizem, etc.)
- Felodipine (Plendil)
- Isradipine (DynaCirc, etc.)
- Nicardipine (Cardene, etc.)
- Nifedipine (Procardia, etc.)
- Nimodipine (Nimotop)
- Nisoldipine (Sular)
- Nitrendipine (Baypress)
- Verapamil (Isoptin, etc.)
PRECIPITANT DRUGS
Antidepressants:
- Fluvoxamine (Luvox, etc.)
- Nefazodone
Comment:
CYP3A4 inhibitors may substantially increase calcium channel blocker (CCB) serum concentrations. 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. Fluvoxamine appears to be a modest CYP3A4 inhibitor but may produce increased CCB concentrations.
Class 3: Assess Risk & Take Action if Necessary
- Consider Alternative: Sertraline (Zoloft), citalopram (Celexa), escitalopram (Lexapro), desvenlafaxine (Pristiq), venlafaxine (Effexor), and paroxetine (Paxil) appear less likely to inhibit CYP3A4 than fluvoxamine. Little is known about the effect of other antidepressants on CCBs.
- Monitor:If alternatives are not appropriate, consider reducing CCB dose and monitor for altered CCB response if inhibitor is initiated, discontinued, or changed in dosage. Watch for hypotension or other evidence of excessive CCB effect.