What is the dose of captopril (angiotensin-converting enzyme inhibitor) for a hypertensive emergency?

From the FDA Drug Label

DOSAGE AND ADMINISTRATION ... For patients with severe hypertension (e.g., accelerated or malignant hypertension), when temporary discontinuation of current antihypertensive therapy is not practical or desirable, or when prompt titration to more normotensive blood pressure levels is indicated, diuretic should be continued but other current antihypertensive medication stopped and captopril dosage promptly initiated at 25 mg bid or tid, under close medical supervision When necessitated by the patient’s clinical condition, the daily dose of captopril may be increased every 24 hours or less under continuous medical supervision until a satisfactory blood pressure response is obtained or the maximum dose of captopril is reached.

The dose of captopril for hypertensive emergency is 25 mg bid or tid, and may be increased every 24 hours or less under close medical supervision until a satisfactory blood pressure response is obtained or the maximum dose of 450 mg is reached 1.

• The initial dose is 25 mg bid or tid.
• The dose may be increased to 50 mg bid or tid, and then to 100 mg bid or tid, and finally to 150 mg bid or tid if necessary.
• A diuretic may also be used in conjunction with captopril therapy.
• Beta-blockers may also be used, but the effects are less than additive.

From the Research

For a hypertensive emergency, captopril can be administered at an initial dose of 25 mg orally, which may be repeated after 1-2 hours if necessary, as supported by a study from 1983 2. The dose can be increased to 50 mg if blood pressure remains elevated. Captopril begins working within 15-30 minutes, with peak effects occurring within 1-2 hours. Some key points to consider when administering captopril for hypertensive emergency include:

• Blood pressure should be monitored closely after administration.
• Patients should remain seated or supine after taking the medication to prevent orthostatic hypotension.
• Captopril works by inhibiting angiotensin-converting enzyme (ACE), which prevents the conversion of angiotensin I to angiotensin II, a potent vasoconstrictor, leading to vasodilation and reduced blood pressure.
• It's also important to note that while captopril can be effective, other medications like labetalol, nicardipine, or clevidipine given intravenously are often preferred for hypertensive emergencies in hospital settings due to their more predictable effects and ability to titrate the dose, as discussed in a study from 2012 3.
• Renal function should be assessed before administration as captopril is contraindicated in bilateral renal artery stenosis and requires dose adjustment in renal impairment. Additionally, a study from 1995 4 mentions that oral nifedipine, captopril, clonidine, labetalol, prazosin, and nimodipine have all been shown to be effective in managing hypertensive urgencies, but the management of hypertensive emergencies often requires parenteral drugs and careful intraarterial blood pressure monitoring. Another study from 2012 5 found that there was no difference between oral and sublingual captopril in terms of efficiency in controlling hypertension in patients with hypertensive urgency, suggesting that oral captopril may be a more convenient choice in these situations. However, the most recent and highest quality study should be prioritized when making a definitive recommendation, and in this case, the study from 2012 3 provides the most relevant information on the management of hypertensive emergencies.