Low dose famotidine and cimetidine in single postprandial doses: a placebo controlled comparative study of overnight pH.

To investigate the relative abilities of low doses of famotidine and cimetidine to raise intragastric pH after a single postprandial evening dose, 16 healthy volunteers were recruited to a four period crossover trial of famotidine 10 mg, cimetidine 100 mg and 200 mg compared with placebo. Intragastric pH was monitored between 1800 and 0730 with a nasogastric pH electrode. Median gastric pH rose from 1.35 (interquartile range 1.1-1.65) with placebo to 1.95 (1.6-5.35, p < 0.001 Friedman rank) after dosing with famotidine 10 mg, to 1.46 (1.3-2.0, 0.05 < p < 0.1) after cimetidine 200 mg, and remained 1.35 (1.1-1.6, p > 0.2) after cimetidine 100 mg. Intragastric pH was above 3 for 34% (p < 0.005) of the time after dosing with famotidine, compared with 13.6% (p > 0.2) after cimetidine 200 mg, 9.5% (p > 0.2) after cimetidine 100 mg, and 4.7% after placebo. The rise of intragastric pH after famotidine 10 mg is significantly greater than that after either 200 mg or 100 mg cimetidine when the drugs are used postprandially.