The pharmacokinetics and dose proportionality of cilazapril

1. The pharmacokinetics and dose proportionality of cilazapril, an orally active angiotensin-converting enzyme (ACE) inhibitor, were investigated in a four-way randomized crossover study in 24 volunteers, over the 0.5 to 5 mg dose range intended for therapeutic use. 2. Plasma concentrations of cilazapril and of the active metabolite cilazaprilat together with plasma ACE activity were determined by radio-enzymatic assay. 3. Plasma concentrations of both cilazapril and cilazaprilat increased in proportion to dose over the range studied. All doses produced substantial inhibition of ACE. Higher doses were associated with earlier onset and longer duration of maximal effect.