Single dose and steady state pharmacokinetics and pharmacodynamics of the ACE-inhibitor imidapril in hypertensive patients

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Abstract

Aims

To investigate the pharmacokinetic profile of the ACE-inhibitor imidapril in 10 hypertensive patients after a first single dose (10 mg) and after 28 days therapy with imidapril 10 mg once daily.

Methods

Cmax, tmax, t1/2 and AUC of imidapril and imidaprilat were obtained. ACE-activity and arterial blood pressure during imidapril were corrected by a preceding placebo-investigation.

Results

The AUC of imidapril was 140 (43 s.d.) ng ml−1 h after the first dose and 123 (34 s.d.) ng ml−1 h at steady state. AUC of the active moiety imidaprilat averaged 211 (101 s.d.) ng ml−1 h after the first dose and 240 (55 s.d.) ng ml−1 h at the steady state investigation. Maximal ACE-inhibition was 75% after the single dose as well as at steady state. ACE inhibition before drug intake at day 28 (i.e. trough) was 50%. The (placebo-corrected) maximal drop in diastolic blood pressure after imidapril was 22 mmHg after the first dose and 25 mmHg at steady state. Exploratory analysis of imidaprilat plasma concentration vs effect profiles suggests a hyperbolic concentration effect relationship where data of the single dose contribute to the ascending part of an Emax-curve, whereas the plateau around Emax is maintained at steady state.

Conclusions

In this group of hypertensive patients, the pharmacokinetic profile and the drop in ACE-activity as well as in blood pressure seen after a single dose of imidapril and at steady state were similar. The initial response to a test dose might therefore predict the response during chronic dosing.

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