Angiotensin II is a potent vasopressor chemical formed from angiotensin I, in the blood by the enzyme angiotensin. It causes the contraction of muscles surrounding the blood vessels and hence, constricts the blood vessels. This increases the pressure within the blood vessels, and causes high blood pressure or hypertension. Ace inhibitors helps in reducing the blood pressure by enlarging or dilating blood vessels. These inhibitors subdue the action of angiotensin converting enzymes, and prevent the conversion of angiotensin to angiotensin II. The reduced blood pressure makes the heart pump blood properly and improve the functionality of a sinking heart. It also helps in reducing the risks of strokes, kidney diseases, diabetes, especially in people suffering from hypertension. The inhibitors reduce the symptoms of peripheral arterial disease (PAD), in which one or more of the blood vessels supplying blood to the legs, become narrow due to atherosclerosis. Ace inhibitors can be taken as a tablet, capsule, liquid, or intravenous (IV) injection. The medicine usually starts affecting the body within one to two hours after each oral dose, and immediately after an IV injection. The inhibitors include medications like benazepril, captopril, cilazapril, fosinopril, perindopril, moexipril, trandolapril, etc. Recent studies have shown that the patients suffering from cardiovascular diseases, who were treated with an Ace inhibitor, lived longer than patients who weren't administered the medication. Some patients do not respond sufficiently to this medication alone, hence it can also be used in combination with other drugs. Side Effects The most common side effect linked with these inhibitors, is a dry and persistent cough which occurs in nearly 20 percent of the patients. It tends to affect women more than men, and starts within one to two weeks after the intake of the medicine. Another severe side effect is hyperkalemia, which is an abnormal increase of the potassium level in the blood. Patients suffering from existing kidney diseases may experience acute renal or kidney failure, or a decline in kidney function. This typically occurs in patients who have existing kidney diseases. Some of the common side effects are:

• Edema (swelling) in the face, mouth, hands, or feet
• Difficulty in swallowing or breathing
• Allergic reaction (sneezing, respiratory congestion, itching, or skin rashes)
• Abdominal pain or swelling
• Fainting (syncope), drowsiness, weakness or fatigue
• Tachycardia (abnormally fast heartbeat)
• Headache, nausea, or upset stomach, vomiting
• Diarrhea
• Abdominal cramps, pain, or distention
• Joint and chest pain
• Abnormal taste (metallic or salty taste)
• Jaundice (rare, but serious)

Ace inhibitors sometimes cause a decrease in the white blood cells, and leave the patient prone to infections. Children under the age of 6 years and pregnant women are advised not to take these inhibitors, especially during the first three trimesters. After the first dose of the medicine, there are possibilities of a 'first dose effect'. Usually the patient's blood pressure drops rapidly, thereby causing dizziness, nausea, and fainting. Therefore, it is recommended to take the medicine around bedtime, and under proper supervision of a doctor or a physician.