Drug Interaction Report

Concomitant use of ACE inhibitors and capsaicinoid topical products may potentiate the cough associated with these agents individually. In 16 healthy volunteers, pretreatment with oral captopril (25 mg) two hours before inhalation of nebulized incremental doses of capsaicin (0.5 to 20 micromol/L in normal saline) resulted in a significant shift of the dose-response curve to capsaicin compared to pretreatment with placebo. The geometric mean dose of capsaicin causing 20 coughs per minute was 1.3 micromol/L for captopril and 2.8 micromol/L for placebo. In a case report, a 53-year-old woman who had been treated with an ACE inhibitor for several years complained of cough each time she applied a 0.075% capsaicin cream to her lower extremities. The patient had not experienced a cough during treatment with the ACE inhibitor alone. However, capsaicin alone may also induce coughing.

GENERALLY AVOID: Moderate-to-high dietary intake of potassium can cause hyperkalemia in some patients who are using angiotensin converting enzyme (ACE) inhibitors. In some cases, affected patients were using a potassium-rich salt substitute. ACE inhibitors can promote hyperkalemia through inhibition of the renin-aldosterone-angiotensin (RAA) system.

MANAGEMENT: It is recommended that patients who are taking ACE inhibitors be advised to avoid moderately high or high potassium dietary intake. Particular attention should be paid to the potassium content of salt substitutes.