Lansoprazole pharmacokinetics and molecular data

Pharmacokinetics
Absorption Distribution Metabolism Elimination

Absorption
The absorption of lansoprazole is rapid, with mean Cmax occurring approximately 1.7 hours after oral dosing, and relatively complete with absolute bioavailability over 80%. In healthy subjects, the mean (± SD) plasma half-life was 1.5 (± 1.0) hours. Both Cmax and AUC are diminished by about 50-70% if the drug is given 30 minutes after food as opposed to the fasting condition. There is no significant food effect if the drug is given before meals. Return to top

Distribution
LANSOPRAZOLE IS 97% BOUND TO PLASMA PROTEINS. PLASMA PROTEIN BINDING IS CONSISTENT OVER THE CONCENTRATION RANGE OF 0.05 TO 5.0 ΜG/ML. Return to top

Metabolism
Lansoprazole is extensively metabolized in the liver. Two metabolites have been identified in measurable quantities in plasma (the hydroxylated sulfinyl and sulfone derivatives of lansoprazole). These metabolites have very little or no antisecretory activity. Lansoprazole is thought to be transformed into two active species which inhibit acid secretion by (H+,K+)-ATPase within the parietal cell canaliculus, but are not present in the systemic circulation. The plasma elimination half-life of lansoprazole does not reflect its duration of suppression of gastric acid secretion. Thus, the plasma elimination half-life is less than 2 hours while the acid inhibitory effect lasts more than 24 hours. Return to top

Elimination
Following single-dose oral administration of Lansoprazole, virtually no unchanged lansoprazole was excreted in the urine. In one study, after a single oral dose of 14C-lansoprazole, approximately one-third of the administered radiation was excreted in the urine and two-thirds was recovered in the feces. This implies a significant biliary excretion of the metabolites of lansoprazole. Return to top