SEVERE HYPOTENSION AND/OR INCREASED FLUID VOLUME REQUIREMENTS HAVE BEEN REPORTED IN PATIENTS RECEIVING NIFEDIPINE TOGETHER WITH A BETA BLOCKING AGENT WHO UNDERWENT CORONARY ARTERY BYPASS SURGERY USING HIGH DOSE FENTANYL ANESTHESIA. IT MAY ELEVATE SERUM CONC. OF DIGOXIN SO CARE SHOULD BE TAKEN FOR DIGOXIN TOXICITY. MAY EFFECT GLUCOSE LEVELS IN DIABETICS. RANITIDINE AND CIMETIDINE INCREASES BIOAVAILABILITY OF NIFEDIPINE AND ITS EFFECT. ADALAT® AND BETA BLOCKING AGENTS IS USUALLY WELL TOLERATED, BUT BEEN OCCASIONAL LITERATURE REPORTS SUGGEST THAT THE COMBINATION MAY INCREASE THE LIKELIHOOD OF CONGESTIVE HEART FAILURE, SEVERE HYPOTENSION OR EXACERBATION OF ANGINA. CO-ADMINISTRATION OF NIFEDIPINE WITH GRAPEFRUIT JUICE RESULTS IN UP TO A 2-FOLD INCREASE IN AUC AND C MAX , DUE TO INHIBITION OF CYP3A4 RELATED FIRST-PASS METABOLISM. EFFECTS OF CALCIUM CHANNEL BLOCKERS IS REDUCED BY PHENYTOIN, CARBAMAZEPINE & PHENOBARBITONES. ITRACONAZOLE, FLUCONAZOLE, CYCLOSPORIN REDUCE ITS METABOLISM. CONCURRENT USE WITH MAGNESIUM SALTS MAY CAUSE PROFOUND HYPOTENSION OR NEUROMUSCULAR BLOCK.
THE DEPRESSION OF CARDIAC CONTRACTILITY, CONDUCTIVITY, AND AUTOMATICITY, AS WELL AS THE VASCULAR DILATION ASSOCIATED WITH ANESTHETICS, MAY BE POTENTIATED BY CALCIUM CHANNEL BLOCKERS. WHEN USED CONCOMITANTLY, ANESTHETICS AND CALCIUM BLOCKERS SHOULD BE TITRATED CAREFULLY. . CONCURRENT USED WITH OTHER CARDIAC DEPRESSANTS SUCH AS AMIODARONE, BETA BLOCKERS, DIGOXIN, AND MEFLOQUINE THERE MAY BE RISK OF BRADYCARDIA AND ATRIOVENTRICULAR BLOCK.