- Type of Drug: Antihypertensive; angiotensimconverting-eozyme (ACE) inhibitor.
- Prescribed for: High blood pressure and congestive heart failure. Low doses may be used to treat mild to moderate high blood pressure. It is also used for the treatment of diabetic kidney disease, as well as high blood pressure associated with some other medical conditions (scleroderma and Takayasu’s disease). Captopril also has been studied as a treatment for rheumatoid arthritis, diagnosis of certain kidney diseases and of primary aldosteronism, swelling and fluid accumulation, Bartter’s syndrome (corrects low blood potassium), relief of Raynaud’s disease, and post-heart-attack treatment when the function of the left ventricle is affected.
Captopril belongs to the class of drugs known as angiotensin-converting-enzyme (ACE) inhibitors. ACE inhibitors work by preventing the conversion of a hormone called angiotensin I to another hormone called angiotensin II, a potent bloodvessel constrictor. Preventing this conversion relaxes blood vessels and helps to reduce blood pressure and relieve the symptoms of heart failure by making it easier for a failing heart to pump blood through the body. The production of other hormones and enzymes that participate in the regulation of blood-vessel dilation is also affected by Captopril and probably plays a role in the effectiveness of this medicine. Captopril usually begins working about 1 hour after taking it.
Some people who start taking Captopril after they are already on a diuretic (water pill) experience a rapid blood-pressure drop after their first dose or when their dose is increased. To prevent this from happening, your doctor may tell you to stop taking your diuretic 2 or 3 days before starting Captopril or increase your salt intake during that time. The diuretic may then be restarted gradually. Heart-failure patients generally have been on Digoxin and a diuretic before beginning Captopril treatment.
Cautions and Warnings
Do not take Captopril if you are allergic to it. It can (rarely) cause very low blood pressure. It may also affect your kidneys, especially if you have congestive heart failure. Your doctor should check your urine for protein content during the first few months of treatment.
Captopril may cause a decline in kidney function. Dosage adjustment of Captopril is necessary if you have reduced kidney function because it is generally eliminated from the body via the kidneys.
Captopril can affect white-blood-cell counts, possibly increasing your susceptibility to infection. Your doctor should monitor your blood counts periodically.
Possible Side Effects
- Most common: rash, itching, and cough; the cough usually goes away a few days after you stop taking the drug.
- Less common: dizziness, tiredness, sleep disturbances, headache, tingling in hands or feet, chest pain, heart palpitations, feeling ill, abdominal pains, nausea, vomiting, diarrhea, constipation, loss of appetite, dry mouth, breathing difficutly, and hair loss.
- Other: fever, angina (chest tightness/pain), heart attack, stroke, abdominal pain, low blood pressure, dizziness when rising from a sitting or lying position, abnormal heart rhythms, sleeping difficulty, hepatitis and jaundice, blood in the stool, unusual skin sensitivity to the sun, flushing, nervousness, reduced sex drive, muscle cramps or weakness, muscle aches, arthritis, bronchitis or other respiratory infections, sinus irritation, weakness, confusion, depression, increased sweating, kidney problems, urinary infection, blurred vision, and swelling of the arms, legs, lips, tongue, face, and throat.
- The blood-pressure-lowering effect of Captopril is additive with diuretic drugs and beta blockers. Any other drug that causes a rapid blood-pressure drop should be used with caution if you are taking Captopril,
- Captopril may increase blood-potassium levels, especially when taken with Dyazide or other potassium-sparing diuretics.
- Captopril may increase the effects of Lithium; this combination should be used with caution.
- Antacids may reduce the amount of Captopril absorbed into the blood. Separate doses of these 2 medicines by at least 2 hours.
- Capsaicin may cause or aggravate the cough associated with Captopril therapy.
- Indomethacin may reduce the blood-pressure-lowering effect of Captopril.
- Phenothiazine tranquilizers and antivomiting agents may increase the effects of Captopril.
- Probenecid increases blood levels of Captopril, thus increasing the drug’s effect as well as the chance of side effects.
- The combination of Allopurinol and Captopril increases the chance of an adverse drug reaction.
- Captopril can increase blood levels of Digoxin, which possibly increases the chance of Digoxin-related side effects.
Captopril is affected by food in the stomach and should be taken on an empty stomach or at least 1 hour before or 2 hours after a meal.
Adult: 75 mg per day to start. Dose may be increased up to 450 mg per day in divided doses, if needed. The dose of this medicine must be tailored to your needs. People with poor kidney function must take less medicine.
Child: about 0.15 mg per pound of body weight 3 times a day.
The principal effect of Captopril overdose is a rapid drop in blood pressure, which can lead to dizziness or fainting. Take the overdose victim to a hospital emergency room immediately. ALWAYS bring the medicine bottle.
Captopril can cause swelling of the face, lips, hands, and feet. This swelling can also affect the larynx (throat) and tongue, and interfere with breathing. If this happens, go to a hospital emergency room at once. Call your doctor if you develop a sore throat, mouth sores, abnormal heartbeat, chest pain, a persistent rash, or Joss of taste perception.
You may get dizzy if you rise to your feet too quickly from a sitting or lying position. Avoid strenuous exercise and/or very hot weather because heavy sweating or dehydration can cause a rapid blood-pressure drop.
Avoid nonprescription diet pills, decongestants, and stimulants that can raise blood pressure while taking Captopril.
If you forget to take a dose of Captopril, take it as soon as you remember. If it is within 4 hours of your next dose, take 1 dose and then another in 5 or 6 hours, then go back to your regular schedule. Do not take a double dose.
ACE inhibitors have caused low blood pressure, kidney failure, slow skull formation, and death in developing fetuses when taken during the last 6 months of pregnancy. Women who are, or may become, pregnant should not take any ACE inhibitors. Sexually active women taking Captopril must use an effective contraceptive method to prevent pregnancy, or use an alternative medicine. If you become pregnant, stop taking the medicine, and call your doctor immediately.
Relatively small amounts of Captopril pass into breast milk, and the effect on a nursing infant has not been determined. Mothers who must take this drug should consider bottle- feeding with formula because infants, especially newborns, are more susceptible to this medicine’s effects than adults.
Older adults may be more sensitive to the effects of Captopril because of normal age-related declines in -kidney or liver function. The dosage must be tailored to individual needs.