Effect of oral famotidine on 24-hour intragastric acidity.

Twenty-four hour intragastric acidity was measured in nine volunteer subjects in a single-blind placebo-controlled cross-over study comparing the effects of famotidine with ranitidine. The volunteer subjects received famotidine (40 mg at night), famotidine (20 mg at night), ranitidine (300 mg at night) or placebo in a predetermined random order. Twenty-four hour intragastric acidity was measured after the seventh dose of each drug or placebo. Famotidine (20 mg), famotidine (40 mg) and ranitidine, all caused a significant decrease of intragastric nocturnal acidity when compared with placebo (P less than 0.01), with no effect during the daytime (P greater than 0.05). Treatment with all the drugs caused a significant rise of fasting plasma gastrin concentration compared with placebo (P less than 0.05).