Duration of effect of lansoprazole on gastric pH and acid secretion in normal male volunteers

Aim: A double-blind, placebo-controlled study to assess the duration of eff ect of lansoprazole 30 mg o.m. on intragastric pH, acid secretion, gastrin levels, the potential for rebound acidity, and the relationship between gas tric acid and drug pharmacokinetic parameters. Methods: Sixteen subjects were treated with lansoprazole 30 mg daily or pla cebo for 14 days, followed by a 7-day post-dosing period and a post-study e valuation on day 28. Ambulatory 24-h pH was recorded and pentagastrin-stimu lated acid secretion measured. Plasma kinetics of lansoprazole were determi ned. Results: Mean intragastric pH in the lansoprazole group increased significa ntly (P < 0.05) from baseline to day 14 compared to placebo. After cessatio n of treatment, secretory activity, as measured by intragastric pH, basal a cid output and stimulated acid output, returned to baseline in 2 to 4 days without any overshoot, indicating the absence of acid rebound. Lansoprazole 's terminal disposition half-life was 1.11 h. Mean pH and serum gastrin ret urned to baseline with half-lives of 22 and 19 h, respectively. Conclusions: Lansoprazole 30 mg daily significantly increases mean intragas tric pH without producing acid rebound. Regeneration of acid production dep ends primarily on de novo synthesis of the acid pump.