OBJECTIVE: To compare the 24-h intragastric pH effects of lansoprazole, 30 mg administered nasogastrically, with pantoprazole, 40 mg administered i.v. METHODS: Healthy adults were enrolled in an open label, two-way crossover, single-center study. Thirty milligrams of lansoprazole (administered nasogastrically in apple juice) or pantoprazole (i.v.) were administered once daily at 8:00 AM for 5 consecutive days with at least a 2-wk washout period between the, regimens. Ambulatory 24-h intragastric pH was monitored at baseline and on days 1 and 5 of each treatment period. Blood specimens were collected on days 1 and 5 for pharmacokinetic parameter determinations. RESULTS: Thirty-three adults completed both crossover periods, with the exception of one patient with a zero lansoprazole plasma concentration on day 1 of period 2. Lansoprazole, 30 mg per nasogastric tube, produced significantly higher mean 24-h intragastric pH values relative to pantoprazole, 40 mg Lv., on both day 1 (3.05 vs 2.76, p < 0.002) and day 5 (3.65 vs 3.45, p = 0.024). Lansoprazole sustained the intragastric pH above 3 (days 1 and 5), 4, and 5 (day 1) significantly longer relative to pantoprazole. Lansoprazole's time to the maximum observed concentration and area under the plasma concentration-time curve over the 24-h time interval increased significantly from day 1 to day 5 (1.7 h vs 2.0 h and 1865 ng<bullet>h/ml vs 2091 ng .h/ml, respectively), and a significant increase in half-life relative to day 1 (0.96 h) was observed on day 5 (1.03 h) during pantoprazole treatment. CONCLUSION: Lansoprazole, 30 mg administered nasogastrically, effectively controls intragastric pH and is an alternative to i.v. pantoprazole in patients who are unable to swallow solid dosage formulations.