ACE inhibitor (short-acting) Pregnancy: Contraindicated — fetal renal failure, oligohydramnios, hypotension, skull hypoplasia, death. Stop immediately if pregnancy detected; switch to labetalol/methyldopa.

Captopril

Brand names: Capoten

Adult dose

Dose: Hypertension: 12.5 mg BD start, titrate to 25–50 mg BD. Heart failure: 6.25 mg under supervision (test dose), then 12.5 mg TDS, titrate to 25–50 mg TDS. Post-MI LV dysfunction: 6.25 mg start within 24 hr (after stable), titrate to 50 mg TDS.

Route: Oral

Frequency: Two to three times daily

Max: 150 mg/day

Take 1 hour before food (food reduces absorption ~30%). Captopril has the shortest half-life of all ACEis — useful for test dosing in HF, but BD/TDS dosing is impractical for long-term use.

Dose adjustments

Renal

eGFR 30–59: max 75 mg/day. eGFR <30: max 12.5 mg BD. eGFR <15 or dialysis: max 12.5 mg OD; use with caution.

Hepatic

Caution; no specific adjustment.

Clinical pearls

First ACE inhibitor (1981) — largely superseded by once-daily ACEis (ramipril, lisinopril, perindopril) for chronic use; BD/TDS dosing impacts adherence.
Niche role for test dosing in advanced HF or hospital initiation — rapid onset (peak 1–1.5 hr) and short duration means recovery is faster if first-dose hypotension occurs.
Side effects more common than with newer ACEis (rash, taste disturbance, proteinuria, neutropenia) — sulfhydryl group implicated.
If switching to long-acting ACEi: stop captopril and start ramipril 1.25–2.5 mg OD (rough conversion).
Always check U&Es 1–2 weeks after start and after each titration; up to 30% rise in creatinine is acceptable.

Contraindications

History of angioedema with any ACEi
Bilateral renal artery stenosis or single functioning kidney with stenosis
Pregnancy (all trimesters — fetal toxicity)
Hereditary angioedema
Concurrent aliskiren in DM or eGFR <60
Concurrent sacubitril-valsartan (within 36 hours)

Side effects

Cough (dry, persistent — 5–35%; class effect, worse with captopril than longer-acting ACEis)
First-dose hypotension (especially HF, salt depletion)
Hyperkalaemia
Acute kidney injury (especially with NSAIDs, dehydration, RAS)
Angioedema (rare — life-threatening, more in Black patients and smokers)
Taste disturbance / loss of taste (captopril more than other ACEi — sulfhydryl group)
Rash, neutropenia, proteinuria (captopril more than newer ACEis)

Interactions

K-sparing diuretics (spironolactone, amiloride), K supplements: hyperkalaemia
NSAIDs: ↓ effect, ↑ AKI risk
Lithium: ↑ levels, toxicity
Diuretics: ↑ first-dose hypotension — withhold for 24 hours before starting
Aliskiren in DM or eGFR <60: contraindicated (ALTITUDE)
Sacubitril-valsartan: contraindicated within 36 hr (angioedema)
Allopurinol: ↑ risk of leucopenia and Stevens-Johnson syndrome

Monitoring

U&Es 1–2 weeks after start, after dose changes, then 6-monthly
BP
Renal function in HF or RAS

Reference: BNF 90; SmPC Capoten; NICE NG136 (Hypertension); NICE NG106 (Chronic HF); SAVE trial NEJM 1992;327:669-77. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways