Intra-oesophageal pH profiles and pharmacokinetics of pantoprazole and esomeprazole

Aim To compare the effect of pantoprazole and esomeprazole on intra-oesophageal pH and investigate their pharmacokinetics in patients with symptomatic gastro-oesophageal reflux disease (GORD). Methods Double-blind, randomized, two-period crossover study. Caucasian men with symptomatic GORD (n= 48) were selected on the basis of clinical records of typical GORD symptoms, confirmed by a pathological reflux time (oesophageal pH < 4 for ≥ 6% of the time). They received oral pantoprazole 40 mg once daily (od) or esomeprazole 40 mg od for seven days. Continuous 24 h oesophageal pH-metry was performed at baseline and day 7. Evaluations included: pre- and post-treatment differences in the percentage of time with pH < 4.0 and < 3.0 between baseline and day 7; area under the curve (AUC), Cmax, and T½; point estimates and 90% confidence intervals (CI) on days 1 and 7, calculated for ratios of the AUC and Cmax. Results Both drugs decreased the mean total number of reflux episodes and reduced the percentage of reflux time within 24 h to < 3%. No pathological reflux was detectable after repeated administration of either drug. The 90% CI were within the predefined range at all time points; thus, equivalence of pantoprazole and esomeprazole was concluded. For pantoprazole, Cmax and AUC were unchanged on day 7 vs day 1, confirming its high and constant bioavailability. For esomeprazole, Cmax and AUC were increased on day 7 vs day 1 by 80% and 50%, respectively, indicating low initial bioavailability. No clinically relevant side effects were seen for either drug. Conclusion Pantoprazole and esomeprazole have equivalent effect on oesophageal pH, since no pathological reflux was detected after treatment with either drug. For esomeprazole, the Cmax and AUC increased after multiple dosing; for pantoprazole the pharmacokinetics were predictable and independent of the number of administered doses.