Increase in plasma aldosterone during prolonged captopril treatment

Area of Science:

• Endocrinology
• Cardiovascular Pharmacology

Background:

• Angiotensin II plays a key role in regulating aldosterone secretion.
• Captopril, an angiotensin-converting enzyme inhibitor, suppresses the renin-angiotensin-aldosterone system.

Purpose of the Study:

• To investigate the long-term effects of angiotensin II suppression with captopril on plasma aldosterone levels.
• To assess the relationship between aldosterone, renin activity, angiotensin II, and blood pressure during captopril therapy.

Main Methods:

• Seven patients were monitored for plasma aldosterone concentration, plasma renin activity, and plasma angiotensin II levels.
• Measurements were taken before and at various time points during long-term captopril administration.

Main Results:

• Plasma aldosterone initially decreased significantly after 1 month of captopril but then increased substantially after 1 year, exceeding pretreatment levels.
• Plasma renin activity remained elevated, and plasma angiotensin II levels were suppressed throughout the study.
• A sustained hypotensive effect was observed in all patients, with initial body weight decrease followed by recovery.

Conclusions:

• Long-term angiotensin II suppression with captopril leads to an initial decrease followed by a significant late increase in plasma aldosterone.
• The mechanism driving this late aldosterone rise under sustained angiotensin II suppression is not yet understood.
• Captopril effectively suppresses angiotensin II and lowers blood pressure long-term, despite paradoxical aldosterone changes.