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. Increased tacrolimus blood levels. Monitor cyclosporine levels in renal transplant patients. Increased exposure to simvastatin. Bisoprolol: Negative influence in contractility, AV conduction & BP w/ verapamil- & diltiazem-type Ca antagonists. Reduced heart rate, cardiac output & vasodilation w/ centrally-acting antihypertensive drugs eg, clonidine, methyldopa, moxonodine, rilmenidine. Increased risk of hypotension & deterioration of ventricular pump function w/ dihydropyridine-type Ca antagonists eg, nifedipine. Potentiated AV conduction time & -ve 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. Intensification of 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).