The effects of low doses of ranitidine on intragastric acidity in healthy men.
BACKGROUND
H2-receptor antagonists are becoming widely available as over-the-counter medications for the treatment of heartburn and excess gastric acidity.


OBJECTIVE
To determine the effects of single low doses of ranitidine on intragastric acidity.


METHODS
Intragastric pH was measured for 9 h after lunch in five studies involving 24 healthy male volunteers. Antacid was given to all subjects on day 1. They then received single oral doses of a study drug 45 min after lunch on four separate occasions: placebo and either ranitidine 25 mg, 75 mg or 125 mg were given double-blind according to a predetermined randomization schedule.


RESULTS
During both of the post-dosing time periods (0-5 h and 5-9 h) there were significant decreases in integrated intragastric acidity for each ranitidine dose compared with placebo (P < 0.0001). There was a significant linear relationship between dose and integrated intragastric acidity with a greater decrease in acidity with increasing ranitidine doses (P < 0.0001). Compared with placebo, time with pH > 3 was significantly greater for ranitidine 75 mg and 125 mg (P < 0.001), but not ranitidine 25 mg. Results with the antacid were similar to placebo.


CONCLUSIONS
Using low doses of ranitidine (25, 75 or 125 mg) there was a dose-related decrease in intragastric acidity for 9 h after dosing. A single dose of antacid did not decrease intragastric acidity significantly.
Wyeth
J W
JW
Royal Free Hospital School of Medicine, London, UK.
Pounder
R E
RE
Sercombe
J C
JC
Snell
C C
CC
D000328:Adult; D003627:Data Interpretation, Statistical; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005744:Gastric Acid; D005745:Gastric Acidity Determination; D005750:Gastric Juice / Q000737:chemistry / Q000187:drug effects*; D006635:Histamine H2 Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D008297:Male; D010919:Placebos; D019518:Postprandial Period / Q000187:drug effects; D011899:Ranitidine / Q000008:administration & dosage / Q000494:pharmacology*; D013997:Time Factors; D016896:Treatment Outcome
D006635:Histamine H2 Antagonists; D010919:Placebos; D011899:Ranitidine