Active and inactive renin after SQ 14225 (Captopril) administration

Area of Science:

• Pharmacology
• Cardiovascular Medicine
• Endocrinology

Background:

• The renin-angiotensin-aldosterone system (RAAS) plays a crucial role in blood pressure regulation.
• Understanding the dynamics of active and inactive renin is vital for managing hypertension.
• Captopril, an angiotensin-converting enzyme (ACE) inhibitor, is a key therapeutic agent for hypertension.

Purpose of the Study:

• To investigate the effects of Captopril on plasma active and inactive renin levels in hypertensive patients.
• To determine if Captopril influences the conversion of inactive renin to active renin.
• To differentiate patient responses to Captopril based on renin activity changes.

Main Methods:

• Oral administration of Captopril (25 mg or 50 mg) to 29 hypertensive patients.
• Measurement of plasma renin activity (PRA) before and after cold storage to calculate inactive renin.
• Classification of patients into responders and non-responders based on active renin response to Captopril.

Main Results:

• In 9 responders, active renin significantly increased, while inactive renin decreased post-Captopril.
• In 20 non-responders, both active and inactive renin showed only minor increases.
• A notable inverse relationship was observed between active and inactive renin changes in responders.

Conclusions:

• Captopril administration appears to modulate renin activity in hypertensive patients.
• The findings suggest that Captopril may facilitate the in vivo conversion of inactive renin to its active form.
• This conversion could be a significant mechanism underlying Captopril's antihypertensive effects.