Effect on AV conduction time may be potentiated & -ve inotropic effect increased w/ class I antiarrhythmics (eg, quinidine, disopyramide; lidocaine, phenytoin; flecainide, propafenone). Effect on AV conduction time may be potentiated w/ class III antiarrhythmics (eg, amiodarone). Risk of profound hypotension & AV block w/ IV verapamil. Risk of worsened heart failure w/ centrally-acting antihypertensives (eg, clonidine, methyldopa, moxonodine, rilmenidine). Abrupt w/drawal of centrally-acting antihypertensives, particularly if prior to β-blocking agent discontinuation, may increase risk of rebound HTN. Increased risk of hypotension w/ Ca antagonists of the dihydropyridine type eg, felodipine & amlodipine; other antihypertensive agents & other medicinal products w/ BP-lowering potential (eg, TCAs, barbiturates, phenothiazines). Topical β-blocking agents (eg, eye drops for glaucoma treatment) may add to the systemic effects of bisoprolol. Increased AV conduction time & risk of bradycardia w/ parasympathomimetics. Increased blood sugar lowering effect of 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. Combination w/ β-sympathomimetic agents (eg, isoprenaline, dobutamine) may reduce effect of both bisoprolol & the co-administered drug. May unmask the α-adrenoceptor-mediated vasoconstrictor effects of sympathomimetics that activate both β- & α-adrenoceptors (eg, noradrenaline, adrenaline). Increased risk of bradycardia w/ mefloquine. Enhanced hypotensive effect & risk for hypertensive crisis w/ MAOIs (except MAO-B inhibitors). Slight t
1/2 reduction w/ rifampicin. Exacerbation of peripheral circulatory disturbances w/ ergotamine derivatives.