With the simultaneous use of verapamil with:
- antiarrhythmic drugs, beta-blockers and inhalation anesthetics, there is an increase in cardiotoxic effect (increased risk of atrioventricular blockade, a sharp decrease in the heart rate, the development of heart failure, a sharp fall in blood pressure);
- antihypertensive agents and diuretics - it is possible to strengthen the hypotensive effect of verapamil;
- digoxin may increase the level of digoxin concentration in the blood plasma due to the deterioration of its excretion by the kidneys (so it is necessary to monitor the level of digoxin in the blood plasma in order to determine its optimal dosage and prevent intoxication);
- cimetidine and ranitidine elevates the level of concentration of verapamil in blood plasma;
- rifampicin, phenobarbital may reduce the concentration in the blood plasma and weaken the action of verapamil;
- theophylline, prazosin, cyclosporin, an increase in the concentration of these substances in the blood plasma is possible;
- muscle relaxants may enhance the muscle relaxant effect; Acetylsalicylic acid increases the possibility of bleeding;
- quinidine increases the level of concentration of quinidine in blood plasma, the threat of lowering blood pressure increases, and in patients with hypertrophic cardiomyopathy, the occurrence of severe arterial hypotension is possible;
- carbamazepine and lithium, the risk of neurotoxic effects increases.