Betacard Drug Interactions

Pharmacodynamics interactions may occur with drugs whose actions enhance or antagonize the various effects of beta blockers at beta₁ and beta₂ receptors, including their antihypertensive effect, cardiodepressant effect, effect on carbohydrate metabolism, or effect on bronchial beta₂ receptors.
Drugs that enhance the antihypertensive effects of beta blockers, such as ACE inhibitors, calcium-channel blocker, and clonidine may be useful in controlling hypertension.
Drugs that cause hypotension such as aldesleukin and general anaesthetics also enhance the antihypertensive effects of beta blockers while other drugs, for example NSAIDs, antagonize the antihypertensive effects. Use of beta blockers with other cardiac depressants such as antiarrhythmics and rate-limiting calcium-channel blockers can precipitate bradycardia and heart block. Beta blockers may potentiate bradycardia due to digoxin. In diabetic patients beta blockers can reduce the response to insulin and oral hypoglycaemics through their effects on pancreatic beta receptors. Blockade of peripheral beta receptors interferes with the effects of sympathomimetics, patients on beta blocker, especially non-selective beta blockers, may develop elevated blood pressure if they are given adrenaline [epinephrine] and the bronchodilator effects of adrenaline [epinephrine] are also inhibited. The response to adrenaline [epinephrine] given for anaphylaxis may be reduced in patients on long-term treatment with beta blockers.
Pharmacokinetic interactions occur with drugs that alter the absorption or metabolism of beta blockers. Although these interactions may alter the beta blocker plasma concentrations, they are not usually clinically significant since there is no association between plasma concentrations and therapeutic effect or toxicity and there are wide interindividual differences in steady-state plasma concentrations of beta blockers. Drugs that reduce absorption include aluminum salts and bile acid binding resins such as colestyramine. Metabolism of some beta blocker can be increased by concomitant treatment with drugs such as barbiturates and rifampicin and decreased with drugs such as cimetidine, erythromycin, fluvoxamine, and hydralazine. Drugs that alter hepatic blood flow also affect metabolism of some beta blocker. Since systemic absorption can occur following ocular use of beta blocker the possibility of interactions with concomitant drugs should be considered.