Effect of Wy-45,727 on 24 h intragastric acidity in twenty normal volunteers.

1. The effects of single daily doses of 20, 50 and 150 mg of WY-45,727, a novel H2-receptor antagonist, and placebo were compared using long term pH-monitoring in 20 male volunteers. 2. Intragastric acidity was measured using combined Ingold glass electrodes. Subjects underwent four studies each under identical dietary conditions. Medication was taken after the evening meal. 3. Median 24 h pH rose from 1.3 (1.2-1.4 interquartile range) on placebo to 1.9 (1.6-2.8) on 20 mg WY-45,727, to 3.1 (2.3-3.7) on 50 mg WY-45,727 and to 4.5 (3.7-4.7) on 150 mg WY-45,727. All three doses increased 24 h and night-time pH significantly compared with placebo (P less than 0.0001). 4. The PAGE test for order effects confirmed clear dose dependent inhibition of acidity (P less than 0.0001). 5. Highly consistent individual responses were found during the night following 150 mg WY-45,727.