Captopril is a white to off-white crystalline powder that may have a slight sulfurous odor; it is soluble in water, methanol, and ethanol and sparingly soluble in chloroform and ethyl acetate. Captopril is a blood pressure-lowering medication which belongs to the class of agents known as angiotensin converting enzyme (or ACE) inhibitors. It blocks the effects of the enzyme which forms angiotensin, the end-product of renin.
Angiotensin converting enzyme inhibitor is an enzyme in the body which is important for the formation of angiotensin II. Angiotensin II causes constriction of arteries in the body, thereby elevating blood pressure. ACE inhibitors such as captopril lower blood pressure by inhibiting the formation of angiotensin II, thus relaxing the arteries. Relaxing the arteries not only lowers blood pressure, but also improves the pumping efficiency of a failing heart and improves cardiac output in patients with heart failure.
Captopril is used to treat high blood pressure and heart failure. It decreases certain chemicals that tighten the blood vessels, so blood flows more smoothly and the heart can pump blood more efficiently. Combining captopril with potassium supplements, potassium containing salt substitutes, and potassium-conserving diuretics such as amiloride (Moduretic), spironolactone (Aldactone), and triamterene (Dyazide, Maxzide), can lead to dangerously high blood levels of potassium. Indomethacin (Indocin) and possibly other anti-inflammatory medications may decrease the blood pressure lowering effect of captopril.