Drug Interaction Report

GENERALLY AVOID: Some beta-blockers may antagonize the bronchodilatory, hypotensive, and tachycardic effects of isoproterenol. The mechanism is blockade of beta-adrenergic receptors, which leads to bronchoconstriction, vasodilation, and increased heart rate. Beta-blockers have been used successfully to treat catecholamine or isoproterenol-induced tachyarrhythmias.

MANAGEMENT: This combination should generally be avoided. Patients who are receiving isoproterenol for cardiac conditions should be closely monitored for adequate therapeutic effect if a beta blocker is added. If no alternative exists, small doses of a B-1 selective beta-blocker (e.g., acebutolol, atenolol, betaxolol, bisoprolol, or metoprolol) may be preferable; however, respiratory status should be closely monitored in patients with obstructive pulmonary disease.

GENERALLY AVOID: Moderate-to-high dietary intake of potassium, especially salt substitutes, may increase the risk of hyperkalemia in some patients who are using angiotensin II receptor blockers (ARBs). ARBs can promote hyperkalemia through inhibition of angiotensin II-induced aldosterone secretion. Patients with diabetes, heart failure, dehydration, or renal insufficiency have a greater risk of developing hyperkalemia.

MANAGEMENT: Patients should receive dietary counseling and be advised to not use potassium-containing salt substitutes or over-the-counter potassium supplements without consulting their physician. If salt substitutes are used concurrently, regular monitoring of serum potassium levels is recommended. Patients should also be advised to seek medical attention if they experience symptoms of hyperkalemia such as weakness, irregular heartbeat, confusion, tingling of the extremities, or feelings of heaviness in the legs.

MONITOR: Coadministration of two or more sympathomimetic agents may increase the risk of adverse effects such as nervousness, irritability, and increased heart rate. Central nervous system (CNS) stimulants, particularly amphetamines, can potentiate the adrenergic response to vasopressors and other sympathomimetic agents. Additive increases in blood pressure and heart rate may occur due to enhanced peripheral sympathetic activity.

MANAGEMENT: Caution is advised if two or more sympathomimetic agents are coadministered. Pulse and blood pressure should be closely monitored.