Betac Drug Interactions

Numerous medicines can induce bradycardia. These include beta-blockers, class Ia antiarrhythmics (quinidine, disopyramide), amiodarone and sotalol in the class III antiarrhythmis, diltiazem and verapamil in the class IV antiarrhythmics, and digitalis glycosides, clonidine, guafancine, mefloquine and anticholinesterase agents indicated in the treatment of Alzheimer's disease.
Contraindicated combinations: Floctafenine: In case of shock or hypotension due to floctafenine, there is a reduction of the compensatory cardiovascular reactions by beta-blockers.
Sultopride: Automatism disorders (excessive bradycardia) due to additive bradycardiac effects.
Inadvisable combinations: Calcium antagonists (bepridil, diltiazem and verapamil): Automatism disorders (excessive bradycardia, sinus arrest), sinoatrial and atrioventricular conduction disturbances and cardiac failure (synergistic effects). Such a combination should only be carried out under close clinical and electrocardiographic monitoring, particularly in elderly patients or at the start of treatment.
Amiodarone: Contractility, automatism and conduction disorders (suppression of the compensatory sympathetic mechanisms).
Combinations requiring precautions for use: Volatile halogenated anaesthetics: Reduction of compensatory cardiovascular reactions by beta-blockers (the beta-adrenergic inhibition may be alleviated during the intervention with beta-stimulants). As a general rule, do not discontinue beta-blocker treatment, and in any case, do not withdraw it abruptly. Inform the anaesthetist of this treatment.
Medicines which may cause torsades de pointes (apart from sultopride): Class Ia (quinidine, hydroquinidine, disopyramide) and class III (amiodarone, dofetilide, sotalol) antiarrhythmics, some phenothiazine neuroleptics (chlorpromazine, cyamemazine, levopromazine, thioridazine), benzamides (amisulpride, sulpride, tiapride), butyrophenone (droperidol, haloperidol), other neuroliptics (pimozide), and other medicines (cisapride, diphemanil, erythromycin IV, halofantrine, mizolastine, moxifloxacin, pentamidine, spiramycin IV, vincamine IV).
Increased risk of ventricular rhythm disturbances, particularly torsades de pointes (hypokalemia is a contributing factor).
Clinical and electrocardiographic monitoring.
Propafenone: Contractility, automatism and conduction disorders (suppression of compensatory sympathetic mechanisms).
Clinical and electrocardiographic monitoring.
Baclofen: Increased antihypertensive effect.
Blood pressure monitoring and dosage adjustment of the antihypertensive agent, if necessary.
Insulin, sulfonylurea hypoglycaemic agents: All beta-blockers may mask certain symptoms of hypoglycaemia, particularly palpitations and tachycardia.
Instruct the patient and reinforce self-monitoring of blood glucose, especially at the start of treatment.
Anticholinesterase agents (ambenomium, donepezil, galantamine, neostigmine, pyridostigmine, rivastigmine, tacrine): Risk of excessive bradycardia (additive bradycardia effects).
Regular clinical monitoring is needed.
Centrally-acting antihypertensive agents (clonidine, apraclonidine, alphamethyldopa, guanfancine, moxonidine, rilmenidine): Significant blood pressure increase in case of sudden withdrawal of the centrally-acting antihypertensive treatment.
Avoid sudden withdrawal of the central antihypertensive treatment.
Clinical monitoring is needed.
Lidocaine by IV route: Increased plasma levels of lidocaine with possible increase of adverse neurological and cardiac effects (reduced hepatic clearance of lidocaine).
Clinical and electrocardiographic monitoring of lidocaine plasma concentrations while receiving the combination and after discontinuation of the beta-blocker.
Adjustment, if necessary of the lidocaine dosage.
Iodine contrast media: In case of shock or hypotension due to iodine contrast media, beta-blockers induce a reduction of the cardiovascular compensatory reactions.
The beta-blocker therapy must be discontinued whenever possible prior to radiological investigation. If continuation of the treatment is essential, the physician must have appropriate resuscitation methods at his/her disposal.
Combinations to be taken into account: NSAIDS (systemic route), including selective COX-2 inhibitors: Reductions of the antihypertensive effect (inhibition of vasodilating prostaglandins by the NSAIDS and sodium and water retention with the pyrazole NSAIDS).
Calcium antagonists (dihydropyridine): Hypotension, cardiac deficiency in patients with latent or uncontrolled cardiac insufficiency. The beta-blocker may also minimise the reflex sympathetic response which occurs in case of excessive hemodynamic alterations.
Imipramine antidepressants, neuroliptics: Increase in antihypertensive effect and risk of orthostatic hypotension (additive effect).
Corticosteroids, tetracosactide: Diminished antihypertensive effect (water and sodium retention of corticosteroids).
Mefloquine: Risk of bradycardia (additive bradycardia effects).
Dipyridamole (IV route): Increased antihypertensive effect.
Alpha-blockers, for urological use (alfuzocin, doxazosin, prazosin, tamsulosin, terazosin): Increased antihypertensive effect.