Drug Interaction Report

MONITOR: Some beta-blockers may increase lidocaine levels and risk of toxicity. This interaction may also apply to topical formulations of lidocaine. The proposed mechanism is inhibition of CYP450 metabolism and/or decreased cardiac output and hepatic blood flow resulting in decreased hepatic metabolism of lidocaine. In addition, beta-blockers and lidocaine may also have additive negative inotropic effects on the heart. Data have been conflicting and variable. The degree of systemic absorption of topical lidocaine may be dependent on the duration of application and the applied surface area.

MANAGEMENT: Patients receiving concurrent therapy should be monitored for drowsiness, mental status changes, bradycardia, and hypotension. Lidocaine levels should be obtained when clinically necessary. If toxicity is suspected, the lidocaine infusion should be decreased, as possible or the topical formulation of lidocaine should be discontinued.

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.