Drug Interactions between Centrum Performance and nimodipine

GENERALLY AVOID: The consumption of grapefruit juice may be associated with significantly increased plasma concentrations of some calcium channel blockers (CCBs) when they are administered orally. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. The interaction has been reported with the dihydropyridine CCBs (in roughly decreasing order of magnitude) felodipine, nisoldipine, nifedipine, and nimodipine, often with a high degree of interindividual variability. Grapefruit juice caused more than twofold increases in felodipine, nifedipine, and nisoldipine AUCs.

MANAGEMENT: The manufacturers of nifedipine and nisoldipine recommend avoiding grapefruit juice. Patients treated orally with other calcium channel blockers should be advised to avoid consumption of large amounts of grapefruits and grapefruit juice to prevent any undue fluctuations in serum drug levels. Increased effects on blood pressure may persist for up to 4 days after the consumption of grapefruit juice. Monitoring for calcium channel blocker adverse effects (e.g., headache, hypotension, syncope, tachycardia, edema) is recommended.

MONITOR: Many psychotherapeutic and CNS-active agents (e.g., anxiolytics, sedatives, hypnotics, antidepressants, antipsychotics, opioids, alcohol, muscle relaxants) exhibit hypotensive effects, especially during initiation of therapy and dose escalation. Coadministration with antihypertensives and other hypotensive agents, in particular vasodilators and alpha-blockers, may result in additive effects on blood pressure and orthostasis.

MANAGEMENT: Caution and close monitoring for development of hypotension is advised during coadministration of these agents. Some authorities recommend avoiding alcohol in patients receiving vasodilating antihypertensive drugs. Patients should be advised to avoid rising abruptly from a sitting or recumbent position and to notify their physician if they experience dizziness, lightheadedness, syncope, orthostasis, or tachycardia. Patients should also avoid driving or operating hazardous machinery until they know how the medications affect them.

MONITOR: Calcium-containing products may decrease the effectiveness of calcium channel blockers by saturating calcium channels with calcium. Calcium chloride has been used to manage acute severe verapamil toxicity.

MANAGEMENT: Management consists of monitoring the effectiveness of calcium channel blocker therapy during coadministration with calcium products.

In general, calcium channel blockers (CCBs) should not be used in patients with hypotension (systolic pressure < 90 mm Hg) or cardiogenic shock. Due to potential negative inotropic and peripheral vasodilating effects, the use of CCBs may further depress cardiac output and blood pressure, which can be detrimental in these patients. The use of verapamil and diltiazem is specifically contraindicated under these circumstances.

In general, calcium channel blockers (CCBs) should not be used in patients with hypotension (systolic pressure < 90 mm Hg) or cardiogenic shock. Due to potential negative inotropic and peripheral vasodilating effects, the use of CCBs may further depress cardiac output and blood pressure, which can be detrimental in these patients. The use of verapamil and diltiazem is specifically contraindicated under these circumstances.

Increased frequency, duration, and/or severity of angina, as well as acute myocardial infarction, have rarely developed during initiation or dosage increase of calcium channel blockers (CCBs), particularly in patients with severe obstructive coronary artery disease and those treated with immediate-release formulations. The mechanism of this effect is not established. Therapy with CCBs should be administered cautiously in patients with significant coronary artery disease.

Calcium channel blockers (CCBs) are extensively metabolized by the liver. The half-lives of CCBs may be prolonged substantially in patients with severe hepatic impairment, with the potential for significant drug accumulation. In addition, the use of some CCBs has been associated with elevations in serum transaminases, both with and without concomitant elevations in alkaline phosphatase and bilirubin. While these effects may be transient and reversible, some patients have developed cholestasis or hepatocellular injury. Therapy with CCBs should be administered cautiously and often at reduced dosages in patients with significantly impaired hepatic function. Periodic monitoring of liver function is advised.

Calcium channel blockers (CCBs) may have varying degrees of negative inotropic effect. Congestive heart failure (CHF), worsening of CHF, and pulmonary edema have occurred in some patients treated with a CCB, primarily verapamil. Some CCBs have also caused mild to moderate peripheral edema due to localized vasodilation of dependent arterioles and small blood vessels, which can be confused with the effects of increasing left ventricular dysfunction. Although some CCBs have been used in the treatment of CHF, therapy with CCBs should be administered cautiously in patients with severe left ventricular dysfunction (e.g., ejection fraction < 30%) or moderate to severe symptoms of cardiac failure and in patients with any degree of ventricular dysfunction if they are receiving a beta-adrenergic blocker. Likewise, caution is advised in patients with acute myocardial infarction and pulmonary congestion documented by X-ray on admission, since associated heart failure may be acutely worsened by administration of a CCB.

Calcium channel blockers (CCBs) may have varying degrees of negative inotropic effect. Congestive heart failure (CHF), worsening of CHF, and pulmonary edema have occurred in some patients treated with a CCB, primarily verapamil. Some CCBs have also caused mild to moderate peripheral edema due to localized vasodilation of dependent arterioles and small blood vessels, which can be confused with the effects of increasing left ventricular dysfunction. Although some CCBs have been used in the treatment of CHF, therapy with CCBs should be administered cautiously in patients with severe left ventricular dysfunction (e.g., ejection fraction < 30%) or moderate to severe symptoms of cardiac failure and in patients with any degree of ventricular dysfunction if they are receiving a beta-adrenergic blocker. Likewise, caution is advised in patients with acute myocardial infarction and pulmonary congestion documented by X-ray on admission, since associated heart failure may be acutely worsened by administration of a CCB.