[Pharmacokinetics of enalapril]

Enalaprilate, an antihypertensive agent that inhibits angiotensin-converting enzyme activity, is not directly absorbable. It is therefore administered as an inactive precursor, an énalaprilate ester which is hydrolysed in vivo with an ultimate bioavailability of 30-40 p. 100. Enalaprilate is entirely excreted through the kidney. With repeated administrations steady state is rapidly reached, and the drug does not accumulate. The effective half-life is 10 hours. Kinetics are linear and depend on renal function. These data, obtained in healthy volunteers with 10 mg doses, also apply to hypertensive patients receiving 20 mg. Following a 20 mg per day dose a more than 50 p. 100 inhibition of the angiotensin-converting enzyme is maintained for 24 hours. In patients with moderate renal impairment or in elderly people (creatinine clearance greater than 30 ml/min), plasma concentrations are slightly increased and there is no need for dosage adjustment. In patients with severe renal impairment (creatinine clearance less than or equal to 30 ml/min) plasma concentrations are considerably increased with a risk of strong accumulation, and dosage must be reduced to 5 or 2.5 mg per day.