Captopril (Capoten) Route of Administration
Captopril is administered orally, not sublingually, despite historical off-label use of the sublingual route in emergency settings. The FDA-approved route is oral administration, taken one hour before meals for optimal absorption 1.
FDA-Approved Administration
- Captopril should be given orally, one hour before meals, as food in the gastrointestinal tract reduces absorption by 30-40% 1.
- Peak blood levels occur at approximately one hour after oral administration of therapeutic doses 1.
- The FDA label makes no mention of sublingual administration as an approved route 1.
Evidence Against Sublingual Administration
Pharmacokinetic Equivalence
- Sublingual and oral captopril produce identical blood pressure reductions and pharmacodynamic effects in comparative studies 2, 3.
- In a randomized study of 40 hypertensive patients, no significant differences were found between oral and sublingual routes in the time course of blood pressure decrease, plasma renin activity increase, or ACE inhibition 2.
- Blood pressure measurements at 0,5,15,30,45, and 60 minutes showed no difference between oral and sublingual administration in 71 patients with hypertensive urgency 3.
Clinical Guideline Position
- Current guidelines recommend oral captopril (not sublingual) for hypertensive urgency, with typical doses of 12.5-25 mg orally 4.
- The European Society of Cardiology lists oral captopril as a first-line agent for hypertensive urgency, with no endorsement of sublingual administration 4.
- Sublingual captopril is not mentioned in major cardiovascular guidelines from the American Heart Association, American College of Cardiology, or European Society of Cardiology for hypertensive crisis management 4.
Historical Context and Current Practice
- Sublingual captopril was historically used based on the assumption of faster absorption, but this hypothesis has been disproven by controlled studies 2.
- While some older studies (1992) reported effectiveness of sublingual captopril 50 mg in hypertensive crisis 5, more recent evidence demonstrates no pharmacokinetic advantage over oral administration 2, 3.
- The unpleasant taste of sublingual captopril causes patient discomfort without providing therapeutic benefit over oral administration 3.
Practical Recommendations
- For routine hypertension management, administer captopril orally one hour before meals 1.
- For hypertensive urgency (BP >180/120 mmHg without organ damage), use oral captopril 12.5-25 mg, not sublingual 4.
- For true hypertensive emergencies with acute organ damage, intravenous agents (labetalol, nicardipine, clevidipine) are indicated, not oral or sublingual captopril 4.
- Observe patients for at least 2 hours after oral captopril administration to evaluate blood pressure-lowering efficacy and safety 4.
Critical Contraindications
- Captopril is absolutely contraindicated in pregnancy due to teratogenic effects of ACE inhibitors 4.
- Bilateral renal artery stenosis is an absolute contraindication due to risk of precipitating renal failure 4.
- Monitor serum potassium and creatinine 2-4 weeks after initiating therapy, particularly when combining with diuretics 6.