The effects of sucralfate on the rate and extent of absorption of ketoprofen, indomethacin, and naproxen were investigated in healthy volunteers. Six volunteers each received sucralfate (2 g) half an hour before a ketoprofen (50 mg) capsule, and, on another occasion, a ketoprofen (50 mg) capsule alone according to a 2 X 2 Latin square pattern of administration. The same design was used for studies with indomethacin (50 mg) capsules and naproxen (500 mg) tablets. Sucralfate decreased significantly (p less than 0.05) the maximum plasma concentrations (Cmax) of ketoprofen, indomethacin, and naproxen. Although the time necessary to attain Cmax (tmax) for the three drugs tended to increase, only for indomethacin was this increase significant. Sucralfate decreased significantly the rate of absorption (ka) of naproxen and indomethacin, but not that of ketoprofen; it had no significant effect on the elimination half-life and area under the plasma concentration as a function of time curves (AUC0----infinity) of the three drugs. Sucralfate thus decreases the Cmax and increases the tmax of ketoprofen, indomethacin, and naproxen without affecting their bioavailabilities.