Captopril Drug Profile

What is Captopril?

Captopril is a medication that belongs to a class of drugs called angiotensin-converting enzyme (ACE) inhibitors. It is primarily prescribed to treat high blood pressure (hypertension) and heart failure by helping blood vessels relax and widen. Captopril was the first ACE inhibitor developed and remains an important treatment option for cardiovascular conditions.

Uses

Captopril is approved for several cardiovascular conditions:

• Hypertension: Lowers blood pressure by reducing the body’s production of substances that constrict blood vessels
• Heart failure: Improves heart function and reduces symptoms like shortness of breath and fluid retention
• Post-heart attack protection: Helps prevent further heart damage and improves survival rates when started after a myocardial infarction
• Diabetic kidney disease: Protects kidney function in patients with diabetes by reducing protein loss in urine
• Left ventricular dysfunction: Helps improve heart pumping efficiency in patients with weakened heart muscle

How it works

Captopril works by blocking the angiotensin-converting enzyme, which is responsible for producing angiotensin II, a hormone that causes blood vessels to narrow and blood pressure to rise. By inhibiting this enzyme, captopril allows blood vessels to relax and widen, reducing blood pressure and making it easier for the heart to pump blood. This mechanism also reduces the workload on the heart and helps protect the kidneys from damage.

Side effects

Common side effects include:

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• Dry, persistent cough
• Dizziness or lightheadedness
• Fatigue or weakness
• Nausea or loss of appetite
• Altered taste sensation (metallic taste)
• Skin rash
• Low blood pressure
• Elevated potassium levels

Serious side effects to watch for:

• Angioedema (swelling of face, lips, tongue, or throat)
• Severe allergic reactions
• Kidney function deterioration
• Extremely low blood pressure
• Dangerously high potassium levels

Warnings and precautions

• Pregnancy: Captopril should not be used during pregnancy, especially in the second and third trimesters, as it can cause serious harm to the developing fetus including kidney problems and death
• Kidney disease: Patients with existing kidney problems require careful monitoring as captopril can worsen kidney function, particularly in those with renal artery stenosis
• Liver disease: Patients with liver impairment may need dosage adjustments and close monitoring
• Dehydration: Patients who are dehydrated or taking diuretics may experience severe drops in blood pressure when starting captopril
• Surgery: Captopril should be discontinued before major surgery as it can cause dangerous drops in blood pressure during anesthesia

Interactions

• Potassium supplements and salt substitutes: Can cause dangerous elevations in blood potassium levels
• Diuretics: May cause excessive blood pressure lowering, especially when starting treatment
• NSAIDs (ibuprofen, naproxen): Can reduce captopril’s effectiveness and increase risk of kidney problems
• Lithium: Captopril can increase lithium levels in the blood, potentially causing toxicity
• Diabetes medications: May enhance blood sugar-lowering effects, requiring dose adjustments
• Other blood pressure medications: Can cause additive blood pressure-lowering effects
• Aliskiren: Should not be used together in patients with diabetes or kidney disease
• Gold injections: May increase risk of serious allergic reactions when used with captopril

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Dosage

Captopril dosing varies based on the condition being treated and individual patient factors. For hypertension, the typical starting dose is 25 mg taken two to three times daily, which may be increased gradually to a maximum of 150 mg three times daily. For heart failure, treatment usually begins with 6.25 to 12.5 mg three times daily, with careful dose increases as tolerated. Captopril should be taken on an empty stomach, at least one hour before meals, as food can reduce its absorption. All dosing decisions should be made by a qualified healthcare provider who will consider factors such as kidney function, other medications, and individual response to treatment.

Sources: FDA DailyMed drug labels (public domain), BNF, WHO Essential Medicines List. This article is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider before starting or stopping any medication.

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