Pharmacokinetics of angiotensin converting enzyme inhibition in tissues following oral lisinopril: studies in the rat using quantitative radioinhibitor binding.

1. The pharmacokinetics of angiotensin converting enzyme (ACE) inhibition in plasma and tissues were measured in the rat following 10 mg/kg lisinopril given by oral gavage. 2. Specific binding of 125I-351A to ACE was measured in plasma, and homogenates of lung, aorta, kidney, testis, epididymis and brain, and used as an index of ACE activity. 3. Plasma ACE binding of 125I-351A was reduced to 5% of that in untreated rats 2 h after treatment, and returned to normal by 48 h. Kidney ACE showed a similar time course. Angiotensin converting enzyme from lung, aorta and brain was inhibited at a slower rate, and to a lesser degree. No significant inhibition of ACE was detected in epididymis or testis. 4. Individual tissues in the rat had differences in time course and degree of ACE inhibition after a single dose of lisinopril.