Intragastric pH after oral administration of single doses of ranitidine effervescent tablets, omeprazole capsules and famotidine fast‐dissolving tablets to fasting healthy volunteers

Abstract

Background: The therapeutic effect of drugs inhibiting acid production on acid‐related discomforts is related to both the onset and duration of action of the drug. The effects on gastric pH by single oral doses of some acid‐inhibiting drugs were investigated by measuring daytime (morning to lunch) intragastric pH in healthy volunteers. Methods: This randomized, single‐dose, 4‐way crossover study included 15 healthy fasting subjects. Effervescent ranitidine tablets 150 and 300 mg, fast‐dissolving famotidine tablets 20 mg and capsules of omeprazole 20 mg were administered. Measurements of intragastric pH were performed every 4 s for 10 min prior to drug administration and during the following 4 h. Results: The effervescent ranitidine tablets (150 or 300 mg) produced similar changes in intragastric pH: following an immediate increase to about pH 5, intragastric pH decreased slightly over the next 10–20 min. Thereafter pH increased steadily, reaching pH 4 after 20–40 min and pH 6 after about 70 min. After famotidine, pH 4 was reached after 80 min, significantly slower than ranitidine. After omeprazole, pH 3 was never reached. Ranitidine 150 and 300 mg showed significantly larger integrated pH responses over the 4‐h observation period, compared to famotidine (P=0.0288 and 0.0074) or omeprazole (P < 0.001). Conclusions: After single‐dose administration to healthy fasting volunteers), ranitidine effervescent tablets showed a significantly more rapid onset of action and a significantly larger integrated pH response compared to either famotidine 20 mg fast‐dissolving tablets or omeprazole 20 mg capsules.