Captopril
A short-acting ACE inhibitor with a sulfhydryl group, used for high blood pressure, heart failure, after a heart attack and diabetic kidney disease.
Drug card
- Class
- ACE inhibitor
- How it works
- Blocking the enzyme that makes angiotensin II, so vessels relax
- Used for
- High blood pressure
- Heart failure
- Weak left ventricle after a heart attack
- Kidney disease in type 1 diabetes
- Known for
- Loss or change of taste
- Neutropenia and agranulocytosis
- Its name
- -pril means an ACE inhibitor
Study it as a flashcard, and it comes back before you forget it.
Mechanism of action
How does captopril work?
Captopril is a proline analogue carrying a sulfhydryl (thiol) group, and it inhibits ACE directly, with no activation step. Its half-life is under 3 hours, so it acts briefly, and food cuts its absorption by 30 to 40%. About half leaves in the urine unchanged.
Like other ACE inhibitors: They block angiotensin-converting enzyme (ACE), so less angiotensin I is turned into angiotensin II. Arterioles relax, aldosterone release falls (potassium rises a little) and renin climbs because angiotensin II no longer holds it back. ACE also breaks down bradykinin; the bradykinin that builds up is thought to cause the dry cough and angioedema.
Uses
What is captopril used for?
- High blood pressure
- Heart failure
- Weak left ventricle after a heart attack
- Kidney disease in type 1 diabetes
Side effects
Side effects of captopril
- Loss or change of tasteKnown for
- Neutropenia and agranulocytosisKnown forSerious
- Itchy rash, sometimes with fever
- Itching without a rash
- Dry cough
- AngioedemaSerious
- High potassium (hyperkalemia)Serious
- Low blood pressure
- Protein in the urine; worsening kidney functionSerious
- Harm to the unborn baby (fetal toxicity)Serious
- Liver injury beginning as cholestatic jaundice (rare)Serious
- Fast heartbeat and palpitations
Known for marks what an exam expects you to know it for.
Watch for
Cautions and what sets it apart
- Kidney impairment or collagen vascular disease such as lupus: neutropenia is far more likely, so white cell counts are checked.
- Proteinuria, sometimes nephrotic syndrome, occurs mostly with earlier kidney disease or high doses.
Good to know: Short-acting and sulfhydryl-containing; best known for taste loss, rash, proteinuria and, in kidney or collagen disease, neutropenia.
Remember it
A way to remember it
CAPTOPRIL
- C
- Cough
- A
- Angioedema
- P
- Potassium up
- T
- Taste change
- O
- hypOtension
- P
- Pregnancy: avoid
- R
- Rash
- I
- Increased renin
- L
- Lower angiotensin II
The letters of captopril, itself an ACE inhibitor, spell out the class's main effects and the pregnancy rule.
A mnemonic widely used in teaching
Its name
-pril means ACE inhibitor
Prodrugs such as enalapril and ramipril are turned into active forms named -prilat (enalaprilat). Don't confuse it with -tril: sacubitril blocks neprilysin, not ACE.
- Every drug name stem
Its class
ACE inhibitors
Other ACE inhibitors with a card:
Easily mixed up with angiotensin receptor blockers and angiotensin receptor-neprilysin inhibitors.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.
Blood pressure
Captopril is one of 27 drugs practiced together here: their classes, how they work, what they treat and what they're known for.
Start Practicing