Captopril Interactions

Drug Interactions: Captopril : Hypotension—Patients On Diuretic Therapy : Patients on diuretics and especially those in whom diuretic therapy was recently instituted, as well as those on severe dietary salt restrictions or dialysis, may occasionally experience a precipitous reduction of blood pressure usually within the first hour after receiving the initial dose of captopril. The possibility of hypotensive effects with captopril can be minimized by either discontinuing the diuretic or increasing the salt intake approximately one week prior to initiation of treatment with captopril or initiating therapy with small doses (6.25 or 12.5 mg). Agents Having Vasodilator Activity : Data on the effect of concomitant use of other vasodilators in patients receiving captopril for heart failure are not available; therefore, nitroglycerin or other nitrates (as used for management of angina) or other drugs having vasodilator activity should, if possible, be discontinued before starting captopril.

Source: FDA drug label - captopril and hydrochlorothiazide

For example, diuretics (e.g., thiazides) may activate the renin-angiotensin-aldosterone system. Agents Increasing Serum Potassium Since captopril decreases aldosterone production, elevation of serum potassium may occur.

Source: FDA drug label - captopril

Captopril 58% 39% Clarithromycin NA 70% Dronedarone NA 150% Gentamicin 129-212% NA Erythromycin 100% NA Itraconazole 80% NA Lapatinib NA 180% Propafenone NA 60-270% Quinidine 100% NA Ranolazine 50% NA Ritonavir NA 86% Telaprevir 50% 85% Tetracycline 100% NA Verapamil 50-75% NA Digoxin concentrations increased less than 50% Atorvastatin 22% 15% Carvedilol 16% 14% Measure serum digoxin concentrations before initiating concomitant drugs.

Source: FDA drug label - digoxin

Loop Diuretics Furosemide administered concurrently with captopril does not alter the pharmacokinetics of captopril in renally impaired hypertensive patients.

Source: FDA drug label - captopril

In a study (n = 6) where terazosin and captopril were administered concomitantly, plasma disposition of captopril was not influenced by concomitant administration of terazosin and terazosin maximum plasma concentrations increased linearly with dose at steady-state after administration of terazosin plus captopril (see DOSAGE AND ADMINISTRATION ).

Source: FDA drug label - terazosin