[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [ACE inhibitors](https://durgical.com/en/pharmacology/classes/ace-inhibitors/) › Captopril

[Pharmacology](https://durgical.com/en/pharmacology/) · [ACE inhibitors](https://durgical.com/en/pharmacology/classes/ace-inhibitors/)

# Captopril

The first ACE inhibitor, short-acting and with a sulfhydryl group. Used for high blood pressure, heart failure and diabetic kidney disease.

Updated 2026-11-01

- Class: [ACE inhibitors](https://durgical.com/en/pharmacology/classes/ace-inhibitors/)
- Enzyme: Angiotensin-converting enzyme (ACE)
- ATC code: C09AA01

✂**Angiotensin-converting enzyme (ACE)**Captopril

ⓘ The figure shows captopril bound to the zinc active site of human testicular ACE (the C-domain form).

**Target in 3D:** Angiotensin-converting enzyme (ACE). PDB structure 1UZF (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/1UZF) · Drag to rotate · pinch to zoom

## Mechanism of action

Captopril binds the zinc in the active site of ACE through its sulfhydryl (thiol) group. Less angiotensin II is made, so arterioles dilate, aldosterone falls and the efferent arteriole of the glomerulus relaxes. Bradykinin, which ACE normally degrades, builds up and adds vasodilation, cough and angioedema. Unlike enalapril, it is active as given, not a prodrug.

- Captopril's thiol group binds the zinc of ACE
- Less angiotensin II and aldosterone; bradykinin builds up
- Arterioles dilate and blood pressure falls

## Pharmacokinetics

**Absorption**
Rapidly absorbed; food in the stomach reduces absorption, so it is given before meals

**Elimination**
Mainly by the kidneys

**Half-life**
Short, so it is given several times a day

## Indications

- High blood pressure [Arterial hypertension →](https://durgical.com/en/conditions/arterial-hypertension/)
- Heart failure [Heart failure →](https://durgical.com/en/conditions/heart-failure/)
- Left ventricular dysfunction after myocardial infarction [Myocardial Infarction (Heart Attack) →](https://durgical.com/en/conditions/myocardial-infarction/)
- Diabetic nephropathy with proteinuria [Chronic kidney disease →](https://durgical.com/en/conditions/chronic-kidney-disease/)

## Adverse effects

### Common

- Dry cough
- Loss or change of taste
- Rash
- Hypotension, especially with the first dose in salt-depleted patients
- Hyperkalaemia

### Serious (rare, important)

- Angioedema
- Neutropenia or agranulocytosis, more likely with kidney disease or collagen-vascular disease
- Proteinuria
- Acute kidney injury with renal artery stenosis
- Fetal toxicity

## Contraindications

- Pregnancy
- Previous angioedema or hypersensitivity with any ACE inhibitor
- Use with sacubitril/valsartan or within 36 hours of it
- Use with aliskiren in people with diabetes

## Key interactions

**Potassium-sparing diuretics, potassium supplements or potassium salt substitutes**
Hyperkalaemia

**NSAIDs, including COX-2 inhibitors**
Weaker effect and risk of kidney injury

**Lithium**
Higher lithium levels and toxicity

## What is monitored

- Blood pressure
- Potassium and creatinine
- White cell count, especially with kidney or autoimmune disease
- Urine protein

## Administration and safety

- Given by mouth before meals, because food lowers absorption
- The first dose can drop blood pressure sharply in patients on diuretics or salt-depleted: the patient lies down and is observed
- Several «-pril» names look alike: the name is checked on every order

## Nursing care

- Check blood pressure before and after the first dose
- Watch for swelling of the lips, tongue or throat and act at once if it appears
- Teach the patient to report fever or sore throat (possible neutropenia)
- Avoid potassium salt substitutes unless prescribed

## Pregnancy and breastfeeding

Contraindicated: drugs acting on the renin-angiotensin system can injure and kill the developing fetus; it is stopped as soon as pregnancy is detected.

## Memory aid

CAPTOPRIL's sulfhydryl brings its own trio: Cough, Altered taste and low neutroPhils.

## Test yourself

Think of the answer, then tap the question to see it.

## Which chemical group of captopril binds ACE and is linked to its special side effects?

The sulfhydryl (thiol) group; captopril is linked to taste changes, rash and neutropenia.

## Why is captopril given before meals?

Food in the stomach reduces its absorption.

## Why is captopril given several times a day, unlike lisinopril?

It has a short half-life, while lisinopril acts much longer.

## Which blood test is watched with captopril in a patient with lupus and kidney disease?

The white cell count, because of the risk of neutropenia or agranulocytosis.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/pharmacology/captopril/)

## Related drugs

- [Enalapril](https://durgical.com/en/pharmacology/enalapril/)
- [Lisinopril](https://durgical.com/en/pharmacology/lisinopril/)
- [Ramipril](https://durgical.com/en/pharmacology/ramipril/)

## Related conditions

- [Arterial hypertension](https://durgical.com/en/conditions/arterial-hypertension/)
- [Heart failure](https://durgical.com/en/conditions/heart-failure/)
- [Myocardial Infarction (Heart Attack)](https://durgical.com/en/conditions/myocardial-infarction/)
- [Chronic kidney disease](https://durgical.com/en/conditions/chronic-kidney-disease/)

[← Back to the class: ACE inhibitors](https://durgical.com/en/pharmacology/classes/ace-inhibitors/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [DailyMed - CAPTOPRIL tablet](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=2d3779b0-83d9-4b6f-a043-f7768cd7fce6) (DailyMed (U.S. National Library of Medicine), 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=C09AA01) (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/pharmacology/captopril/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/captopril/