Nocturnal Gastric Acidity and Nocturnal Esophageal Acidity Are Lower with Immediate-Release Omeprazole Than with Lansoprazole or Esomeprazole in GERD Patients Treated with a Proton Pump Inhibitor

Purpose: Nocturnal esophageal acidity is particularly important in the pathophysiology of GERD and proton pump inhibitors (PPIs) reduce nocturnal esophageal acidity by reducing nocturnal gastric acidity. Often, comparing mean or median values for gastric or esophageal acidity with one PPI to corresponding values with another PPI may obscure important differences between effects of the two agents on acidity. Our aim was to use Bayesian analyses to compare the relative abilities of immediate-release omeprazole (IR-OME), lansoprazole (LAN), and esomeprazole (ESO) to decrease nocturnal gastric and nocturnal esophageal acidity in GERD patients. Methods: Gastric and esophageal pH were measured for 24 hours in 49 GERD patients on the 7th day of dosing with 40 mg IR-OME, 30 mg LAN or 40 mg ESO in a 3-way crossover study with at least a 10-day washout period between each treatment. Dosing occurred at 10 PM and the nocturnal period was from 10 PM until 6 AM the next morning. Nocturnal acidity was calculated both as integrated acidity (mmol.hr/L) and as time pH < 4 (%). We used Bayes’ rule, which provides a useful method for combining new information with a prior probability, to calculate the posterior probability that nocturnal gastric or esophageal acidity with IR-OME was lower than that with ESO or LAN. For these calculations we used a flat prior probability that considered all values from 0 to 1.00 to be equally probable. Results: The table below shows that with integrated acidity, the posterior probability that nocturnal gastric and esophageal acidity are lower with IR-OME than with ESO or LAN is at least 0.96. With time pH < 4, the posterior probabilities that IR-OME < LAN were the same as those with integrated acidity. On the other hand, with time pH < 4, the posterior probabilities that IR-OME < ESO were the lower than those with integrated acidity. Conclusion: Thus, in GERD patients treated with a PPI, there is a high probability that during the nocturnal period, both gastric and esophageal acidity will be lower with IR-OME than with ESO or LAN.Table: Posterior Probabilities of Lower Nocturnal Acidity with IR-OME