Amlodipine: Increased risk of hypotension w/ strong or moderate CYP3A4 inhibitors eg, PIs, azole antifungals, macrolides, verapamil, diltiazem. Different plasma conc w/ CYP3A4 inducers eg, rifampicin,
Hypericum perforatum. Increased BP-lowering effects w/ grapefruit or grapefruit juice. Lethal ventricular fibrillation & CV collapse associated w/ hyperkalemia w/ verapamil & IV dantrolene. Additive BP-lowering effects w/ other antihypertensives. Increased exposure to simvastatin. Increased tacrolimus blood levels. Monitor cyclosporine levels in renal transplant patients. Bisoprolol: Negative influence on contractility, AV conduction & BP w/ verapamil- & diltiazem-type Ca antagonists. Profound hypotension & AV block w/ IV verapamil. Reduced heart rate, cardiac output & vasodilation w/ centrally-acting antihypertensive drugs eg, clonidine, methyldopa, moxonidine, rilmenidine. Increased risk of hypotension & further deterioration of ventricular pump function w/ dihydropyridine-type Ca antagonists eg, nifedipine. Potentiated AV conduction time & negative inotropic effect w/ class I antiarrhythmics eg, disopyramide, quinidine, lidocaine, phenytoin, flecainide, propafenone. Potentiated AV conduction time w/ class III antiarrhythmics eg, amiodarone. Increased AV conduction time & risk of bradycardia w/ parasympathomimetic drugs. Additive systemic effects w/ topical β-blocker-containing prep eg, glaucoma treatment eye drops. Intensified blood sugar-lowering effect w/ insulin & oral antidiabetics. Attenuated reflex tachycardia & increased risk of hypotension w/ anaesth. Reduced heart rate, increased AV conduction time w/ digitalis glycosides. Reduced hypotensive effect w/ NSAIDs. Reduced effect w/ β-sympathomimetics eg, isoprenaline, dobutamine. Increased BP w/ norephinephrine, epinephrine. Increased risk of hypotension w/ antihypertensive agents & other drugs w/ BP-lowering potential eg, TCAs, barbiturates, phenothiazines. Increased risk of bradycardia w/ mefloquine. Enhanced hypotensive effect w/ MAOIs except MAO-B inhibitors.