Pharmacodynamic evaluation of 4 angiotensin-converting enzyme inhibitors in healthy adult horses.

This study focuses on testing the efficacy of four different angiotensin-converting enzyme (ACE) inhibitors in horses, with results showing that benazepril was the most effective at inhibiting ACE activity.

Study Objective and Methodology

• The study aims to analyze how serum ACE inhibition differs among four ACE inhibitors, due to the limited available data on their efficacy in horses. The experiment involved healthy adult horses and had a prospective, randomized design for control and consistency.
• Focusing on a Latin square design, horses were given one of the four ACE inhibitors via an intragastric route, at one of two doses. The ACE inhibitors used were benazepril, ramipril, quinapril, and perindopril.
• The activity of the serum ACE was observed using a kinetic spectrophotometric method, which measures the changes in the color intensity of a solution.

Results and Findings

• The study found that both the type of drug and its dosage have a considerable impact on ACE inhibition, measured by maximum ACE inhibition (I(max)), ACE inhibition 24 hours post-administration (I(24h)), and the area under the curve (AUC(0-48h)).
• Benazepril, specifically at the high dosage of 0.5 mg/kg, resulted in significantly higher I(max) and I(24h) compared to the other three drugs investigated in the study.
• All drugs leads to a significant decrease in indirect blood pressure over time after administration. However, the differences in blood pressure reduction were not significantly different between the drugs.
• The pharmacodynamic variables, measures after administering benazepril to horses which were not fasting, were not significantly different from those seen after fasting.
• Giving benazepril orally every day for a week did not result in a cumulative effect on ACE inhibition.

Concluding Remarks

• Based on the study’s findings, benazepril presented as the most effective ACE inhibitor at the given dosage (0.5 mg/kg) in inhibiting serum ACE activity in healthy horses.
• However, more comprehensive studies might be needed to determine the long-term benefits and potential side effects of benazepril and other ACE inhibitors in horses. Also, studies should explore their effectiveness in horses with cardiovascular disorders.