Related Experiment Videos
Hemodynamic and antihypertensive effects of captopril, an orally active angiotensin converting enzyme inhibitor
Insights
Captopril effectively lowers blood pressure in patients with essential hypertension (EH) and renovascular hypertension (RVH). This medication reduces total peripheral resistance, leading to improved blood pressure control.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Hypertension, a condition of elevated blood pressure, poses significant health risks.
- Essential hypertension (EH) and renovascular hypertension (RVH) are common forms of high blood pressure.
Purpose of the Study:
- To evaluate the efficacy of captopril in treating patients with essential hypertension (EH) and renovascular hypertension (RVH).
- To investigate the hemodynamic effects of captopril, including its impact on blood pressure and peripheral resistance.
Main Methods:
- Fifteen patients (11 EH, 4 RVH) with diastolic blood pressure > 95 mm Hg were treated with ascending doses of captopril (10-1000 mg/day).
- Blood pressure, plasma renin activity (PRA), and cardiac output were monitored. Total peripheral resistance was calculated.
- Patients were maintained on a 100 mEq sodium diet during the study.
Main Results:
- Captopril normalized blood pressure in 12 out of 15 patients.
- Average diastolic blood pressure decreased significantly in both EH and RVH groups (p < 0.001 and p < 0.005, respectively).
- Total peripheral resistance decreased by 18.9% (p < 0.05) in most patients, while cardiac output remained unchanged. Converting enzyme activity was halved, and PRA increased sevenfold.
Conclusions:
- Captopril is an effective antihypertensive agent for patients with EH and RVH.
- The blood pressure-lowering effect of captopril is primarily attributed to a reduction in total peripheral resistance.
Abstract:
Captopril inhibits angiotensin II formation and bradykinin degradation in vivo. Eleven patients with essential hypertension (EH) and four patients with renovascular hypertension (RVH) were treated with captopril for periods ranging from 3 days to 12 months. All patients had a diastolic blood pressure (DBP) over 95 mm Hg after receiving a placebo for 3 days. Captopril given in ascending doses (10-1000 mg/day) caused normalization of blood pressure in all but three patients, one with severe RVH whose pressure fell 11%, one patient with severe EH, whose pressure fell 27%, and one with EH whose blood pressure fell 8.5%. The average control DBP in patients with EH was 113.7 +/- 5.5 (SE) mm Hg and fell to 89.9 +/- 3.6 mm Hg (p less than 0.001), while DBP in patients with RVH fell from 110.7 +/- 7.6 mm Hg to 94.5 +/- 8.2 (p less than 0.005). All patients were studied in balance on a 100 mEq sodium (Na) diet. Plasma renin activity (PRA) versus 24-hour urinary Na excretion increased sevenfold during therapy while converting enzyme activity fell by about one half. The magnitude of the blood pressure response was not related to control PRA. Cardiac output was estimated by echocardiography during placebo administration and during maintenance therapy with captopril. A significant change was not observed. Total peripheral resistance fell an average of 18.9% (p less than 0.05) in 11 of the 13 patients in whom the measurement could be made. It is concluded that captopril effectively lowers blood pressure in patients with EH or RHV by reducing total peripheral resistance.