Drug Interaction Report

MONITOR: Coadministration with beta-2 adrenergic agonists may potentiate the hypokalemic effects of potassium-wasting diuretics. Beta-2 agonists can cause clinically significant but usually transient decreases in serum potassium concentrations. Since QT prolongation is a possible side effect of beta-2 agonists, exacerbation of hypokalemia may increase the risk of torsade de pointes and other serious arrhythmias. The interaction may be more likely with systemic or nebulized formulations of beta-2 agonists, high dosages of inhaled beta-2 agonists, or concomitant theophylline or corticosteroid therapy.

MANAGEMENT: Caution is advised when beta-2 agonists are used with potassium-wasting diuretics. Serum potassium level and cardiovascular status should be monitored, especially if the beta-2 agonist is administered systemically or by nebulizer. Patients should be advised to notify their physician if they experience potential signs and symptoms of hypokalemia such as fatigue, weakness, myalgia, muscle cramps, numbness, tingling, abdominal pain, constipation, palpitation, and irregular heartbeat.

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.