Rapid effect of lansoprazole on intragastric pH: a crossover comparison with omeprazole

Background: The time to onset of acid inhibition is considered an important factor when treating patients with reflux symptoms. This study was therefo re designed to investigate the effect of 30 mg lansoprazole and 20 mg omepr azole on gastric pH after single-dose administration. Methods: The study wa s of a randomized, open-label, single-dose and two-way crossover design wit h a washout period of at least 7 days in between. Fifteen healthy adult mal e and female subjects were included. The subjects were intubated with a pH catheter. Intragastric pH was measured every 4th sec for 10 min before and during 8 h after drug administration. Blood samples, for determination of p lasma concentrations of lansoprazole and omeprazole, were obtained on 10 oc casions during 6 h after drug administration. The area under the curve (AUC ), the elimination halflife (t(1/2)), and the peak concentration (C-max) of the two drugs were calculated. Results: All subjects completed the study w ithout major complications. The mean pH (0-8 h) after drug administration w as 2.9 for lansoprazole and 2.0 for omeprazole (P = 0.0058). A pH of more t han 4 was reached for the first time after 130 min with lansoprazole and af ter 250 min with omeprazole. AUC was 4919 +/- 2526 nmol/l x h for lansopraz ole and 1352 +/- 1120 nmol/l x h for omeprazole. Conclusion: Single-dose ad ministration of 30 mg lansoprazole is followed by a rapid absorption of the drug and hence a more efficient acid suppression than after single-dose ad ministration of 20 mg omeprazole in healthy volunteers.