What captopril dose is equivalent to lisinopril 5 mg taken once daily?

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Last updated: February 21, 2026 • View editorial policy

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Captopril Dose Equivalent to Lisinopril 5 mg

For a patient taking lisinopril 5 mg once daily, convert to captopril 25 mg three times daily (total 75 mg/day), using the established 5:1 conversion ratio.

Conversion Ratio and Dosing Equivalence

  • The conversion from captopril to lisinopril follows a 5:1 daily dosage ratio, meaning 5 mg of captopril is equivalent to 1 mg of lisinopril. 1
  • A prospective randomized trial demonstrated that converting from captopril to lisinopril at this 5:1 ratio maintained comparable blood pressure control in patients with mild-to-moderate hypertension. 1
  • For lisinopril 5 mg once daily, the equivalent captopril dose is 25 mg three times daily (total daily dose of 75 mg captopril = 15 mg lisinopril equivalent, but starting at the 5:1 ratio from the baseline 5 mg lisinopril). 1

Guideline-Supported Dosing Regimens

Captopril Dosing

  • ACC/AHA guidelines recommend starting captopril at 6.25 or 12.5 mg three times daily and gradually titrating to 50 mg three times daily for heart failure. 2
  • The target maintenance dose range for captopril in hypertension is 25–50 mg three times daily. 3
  • In the SAVE trial, the mean daily captopril dose was 127 mg, demonstrating that higher doses provide mortality benefit in patients with left ventricular dysfunction. 3

Lisinopril Dosing

  • Lisinopril 5 mg once daily is an appropriate starting dose, particularly in elderly patients or those not on diuretics. 4
  • The ATLAS trial compared low-dose lisinopril (2.5–5 mg daily) versus high-dose lisinopril (32.5–35 mg daily), with higher doses showing superior outcomes. 3
  • Maintenance doses of lisinopril range from 5–20 mg daily for hypertension and heart failure. 3

Practical Conversion Algorithm

  1. Calculate the equivalent daily dose: Multiply lisinopril 5 mg by 5 to get 25 mg total daily captopril dose.
  2. Divide into three daily doses: Captopril requires three-times-daily dosing due to its shorter half-life, so prescribe 8.3 mg three times daily (round to practical dosing of 6.25 mg or 12.5 mg TID). 1, 5
  3. Start conservatively: Begin with captopril 6.25 mg three times daily and titrate to 12.5–25 mg three times daily based on blood pressure response. 2, 3
  4. Monitor within 1–2 weeks: Check blood pressure, serum creatinine, and potassium levels after conversion. 3

Clinical Considerations

Pharmacokinetic Differences

  • Lisinopril has a longer half-life and provides 24-hour blood pressure control with once-daily dosing, whereas captopril requires three-times-daily administration. 5
  • A head-to-head trial showed that once-daily lisinopril was more effective than twice-daily captopril in reducing 24-hour ambulatory blood pressure, with captopril showing two blood pressure troughs during the dosing interval. 5
  • In heart failure patients, lisinopril produced greater improvement in exercise duration and left ventricular ejection fraction compared to captopril, particularly in those with renal impairment or severely reduced ejection fraction (<35%). 6

Titration Strategy

  • Avoid excessive diuresis before initiating ACE inhibitor therapy, and consider reducing or withholding diuretics for 24 hours before starting captopril. 3
  • Increase captopril dose gradually at 5–7 day intervals, rechecking potassium and creatinine after each dose adjustment until values stabilize. 3
  • The target captopril dose for optimal outcomes in heart failure is 50 mg three times daily (150 mg/day total). 2, 3

Monitoring Requirements

  • Recheck blood pressure 5–7 days after conversion to assess efficacy and detect hypotension. 3
  • Monitor renal function and electrolytes within 1 week of conversion, then at 3 months, and subsequently every 6 months. 3
  • Avoid potassium-sparing diuretics during the initiation phase to prevent hyperkalemia. 3
  • Avoid NSAIDs and COX-2 inhibitors, which can blunt ACE inhibitor efficacy and worsen renal function. 3

Common Pitfalls to Avoid

  • Do not use twice-daily captopril dosing as a substitute for three-times-daily dosing; the shorter half-life requires TID administration for consistent 24-hour blood pressure control. 5
  • Do not underdose captopril; the conversion ratio of 5:1 is well-established, and using lower doses may result in inadequate blood pressure control. 1
  • Do not combine captopril with other ACE inhibitors or ARBs, as dual RAAS blockade increases the risk of hyperkalemia, syncope, and acute kidney injury without added benefit. 3
  • Recognize that lisinopril offers superior convenience with once-daily dosing and may provide better 24-hour blood pressure control than captopril, so conversion from lisinopril to captopril should only be done when clinically necessary (e.g., cost, availability, or specific patient factors). 1, 5

References

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This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.