The effect of GR122311X, a bismuth compound with H2-antagonist activity, on 24-hour intragastric acidity.

GR122311X (ranitidine bismuth citrate Glaxo Group Research Ltd) is a bismuth compound with histamine H2-receptor antagonist activity. The gastric acid antisecretory activity of three oral dosage regimens of GR122311X was compared with placebo and 150 mg ranitidine b.d. The median 24-h integrated intragastric acidity was 38, 26 and 18% of the median placebo value during dosing with GR122311X 196, 391 and 782 mg b.d., respectively. The 24-h acid suppression with GR122311X 391 mg b.d. was not significantly different to that produced by 150 mg ranitidine b.d. (24% of placebo acidity). The median 24-h urinary bismuth excretion increased with rising dosage of GR122311X from 19.2 micrograms with 196 mg b.d., to 36.4 micrograms with 391 mg b.d., to 68.7 micrograms with 782 mg b.d. In conclusion, GR122311X is an effective antisecretory agent with modest systemic bismuth absorption.