NIMODIPINE Drug Interactions: What You Need to Know

INTERACTIONS

• Anti-Hypertensives : May increase risk of hypotension. Monitor blood pressure. (7.1)
• CYP3A4 Moderate and Weak Inhibitors: May increase risk of hypotension. Monitor blood pressure. Dose reduction of nimodipine may be needed. Avoid grapefruit juice. (7.2)
• CYP3A4 Moderate and Weak Inducers: May reduce efficacy of nimodipine. Dose increase may be needed. (7.3)

7.1 Blood Pressure Lowering Drugs Nimodipine may increase the blood pressure lowering effect of concomitantly administered anti-hypertensives such as diuretics, beta-blockers, ACE inhibitors, angiotensin receptor blockers, other calcium channel blockers, α-adrenergic blockers, PDE5 inhibitors, and α-methyldopa.

In

Europe, nimodipinewas observed to occasionally intensify the effect of antihypertensive drugs taken concomitantly by hypertensive patients; this phenomenon was not observed in North American clinical trials. Blood pressure should be carefully monitored, and dose adjustment of the blood pressure lowering drug(s) may be necessary.

7.2 CYP3A4 Inhibitors Nimodipine plasma concentration can be significantly increased when concomitantly administered with strong CYP3A4 inhibitors. As a consequence, the blood pressure lowering effect may be increased. Therefore, the concomitant administration of nimodipine and strong CYP3A4 inhibitors should generally be avoided <span class="opacity-50 text-xs">[see Warnings and Precautions (5.3) ]</span>. Strong CYP3A4 inhibitors include some members of the following classes: - macrolide antibiotics (e.g., clarithromycin, telithromycin), - HIV protease inhibitors (e.g., indinavir, nelfinavir, ritonavir, saquinavir), - HCV protease inhibitors (e.g., boceprevir, telaprevir), - azole antimycotics (e.g., ketoconazole, itraconazole, posaconazole, voriconazole), - conivaptan, delavirdine, nefazodone Nimodipine plasma concentration can also be increased in the presence of moderate and weak inhibitors of CYP3A4. If nimodipine is concomitantly administered with these drugs, blood pressure should be monitored, and a reduction of the nimodipine dose may be necessary. Moderate and weak CYP3A4 inhibitors include alprozalam, ameprenavir, amiodarone, aprepitant, atazanavir, cimetidine, cyclosporine, diltiazem, erythromycin, fluconazole, fluoxetine, isoniazid, oral contraceptives, quinuprestin/dalfopristin, valproic acid, and verapamil. A study in eight healthy volunteers has shown a 50% increase in mean peak nimodipine plasma concentrations and a 90% increase in mean area under the curve, after a one-week course of cimetidine at 1,000 mg/day and nimodipine at 90 mg/day. This effect may be mediated by the known inhibition of hepatic cytochrome P-450 (CYP) by cimetidine, which could decrease first-pass metabolism of nimodipine. Grapefruit juice inhibits CYP3A4. Ingestion of grapefruit/grapefruit juice is not recommended while taking nimodipine.

7.3 CYP3A4 Inducers Nimodipine plasma concentration and efficacy may be significantly reduced when concomitantly administered with strong CYP3A4 inducers. Therefore, concomitant use of nimodipine with strong CYP3A4 inducers (e.g., carbamazepine, phenobarbital, phenytoin, rifampin, St. John’s wort) should generally be avoided <span class="opacity-50 text-xs">[see Warnings and Precautions (5.4) ]</span>. Moderate and weak inducers of CYP3A4 may also reduce the efficacy of nimodipine. Patients on these should be closely monitored for lack of effectiveness, and a nimodipine dosage increase may be required. Moderate and weak CYP3A4 inducers include, for example: amprenavir, aprepitant, armodafinil, bosentan, efavirnenz, etravirine, Echinacea, modafinil, nafcillin, pioglitazone, prednisone, rufinamide, and vemurafenib.

CONTRAINDICATIONS The concomitant use of nimodipine with strong inhibitors of CYP3A4 such as some macrolide antibiotics (e.g., clarithromycin, telithromycin), some anti-HIV protease inhibitors (e.g., delaviridine, indinavir, nelfinavir, ritonavir, saquinavir), some azole antimycotics (e.g., ketoconazole, itraconazole, voriconazole) and some antidepressants (e.g., nefazadone) is contraindicated because of a risk of significant hypotension (see PRECAUTIONS, Drug Interactions ).

AND PRECAUTIONS Hypotension: Monitor blood pressure. (5.1)

• Patients with Cirrhosis: Higher risk of adverse reactions. Monitor blood pressure and pulse. (5.2)
• CYP3A4 Strong Inhibitors: May significantly increase risk of hypotension. Concomitant use with nimodipine should generally be avoided. (5.3)
• CYP3A4 Strong Inducers: May significantly reduce efficacy of nimodipine. Concomitant use with nimodipine should generally be avoided. (5.4)

5.1 Hypotension Blood pressure should be carefully monitored during treatment with nimodipine. In clinical studies of patients with subarachnoid hemorrhage, about 5% of nimodipine-treated patients compared to 1% of placebo-treated patients had hypotension and about 1% of nimodipine-treated patients left the study because of this <span class="opacity-50 text-xs">[see Adverse Reactions (6) ]</span>.

5.2 Possible Increased Risk of Adverse Reactions in Patients with Cirrhosis Given that the plasma levels of nimodipine are increased in patients with cirrhosis, these patients are at higher risk of adverse reactions. Therefore, monitor blood pressure and pulse rate closely and administer a lower dosage <span class="opacity-50 text-xs">[see Dosage and Administration (2.4) , Clinical Pharmacology (12.3) ]</span>.

5.3 Possible Increased Risk of Hypotension with Strong CYP3A4 Inhibitors Concomitant use of strong inhibitors of CYP3A4, such as some macrolide antibiotics (e.g., clarithromycin, telithromycin), some HIV protease inhibitors (e.g., indinavir, nelfinavir, ritonavir, saquinavir), some HCV protease inhibitors (e.g., boceprevir, telaprevir), some azole antimycotics (e.g., ketoconazole, itraconazole, posaconazole, voriconazole), conivaptan, delavirdine, and nefazodone with nimodipine should generally be avoided because of a risk of significant hypotension <span class="opacity-50 text-xs">[see Drug Interactions (7.2) ]</span>.

5.4 Possible Reduced Efficacy with Strong CYP3A4 Inducers Concomitant use of strong CYP3A4 inducers (e.g., carbamazepine, phenobarbital, phenytoin, rifampin, St. John’s wort) and nimodipine should generally be avoided, as nimodipine plasma concentration and efficacy may be significantly reduced <span class="opacity-50 text-xs">[see Drug Interactions (7.3) ]</span>.