Lisinopril - Pharmacokinetics and Metabolism

Pharmacokinetics and Metabolism

For adult patients, following oral administration of lisinopril, peak serum concentrations occur within about seven hours, although there was a trend to a small delay in time taken to reach peak serum concentrations in acute myocardial infarction patients. Declining serum concentrations exhibit a prolonged terminal phase which does not contribute to drug accumulation. This terminal phase probably represents saturable binding to ACE and is not proportional to dose. Lisinopril does not appear to be bound to other serum proteins.

Lisinopril does not undergo metabolism and is excreted unchanged entirely in the urine. Based on urinary recovery, the mean extent of its absorption is approximately 25%, with large intersubject variability (6–60%) at all doses tested (5–80 mg). Lisinopril absorption is not influenced by the presence of food in the gastrointestinal tract. Its absolute bioavailability is reduced to about 16% in patients with stable NYHA Class II-IV congestive heart failure, and the volume of distribution appears to be slightly smaller than that in normal subjects.

The oral bioavailability of lisinopril in patients with acute myocardial infarction is similar to that in healthy volunteers. Upon multiple dosing, it exhibits an effective half-life of accumulation of 12 hours.

Impaired renal function decreases elimination of lisinopril, which is excreted principally through the kidneys, but this decrease becomes clinically important only when the glomerular filtration rate is below 30 ml/min. Above this rate, the elimination half-life is little changed. With greater impairment, however, peak and trough levels increase, time to peak concentration increases, and time to attain steady state is prolonged. Older patients, on average, have (approximately doubled) higher blood levels and area under the plasma concentration time curve (AUC) than younger patients.