RANITIDINE "SIGNIFICANT SUPERIORITY"
RANITIDINE "SIGNIFICANT SUPERIORITY" v. CIMETIDINE IN MAINTENANCE against ulcer recurrence was found in a study of 484 patients published in the Sept. 22 issue of the Lancet. The randomized, double-blind, parallel study by K. R. Gough, et al, compared the recommended bedtime doses of 150 mg ranitidine and 400 mg cimetidine given for a year to prevent the relapse of recently healed duodenal ulcers. "The annual ulcer relapse rate was 23% with ranitidine and 37% with cimetidine," the investigators reported. Glaxo researchers participated in the Gough study, which is one of four studies Glaxo has submitted to FDA in support of a maintenance therapy claim. Patients were examined by endoscopy before the trial and after four, eight, and 12 months. According to the authors, "ulcer relapse rate was consistently and significantly lower on ranitidine than on cimetidine (8% v. 21%, p=0.0018 at four months; 14% v. 34%, p<0.0001 at eight months; and 23% v. 37%, p=0.004 at 12 months)." Gough, et al, stated that the prophylactic benefit is "probably related to pharmacodynamic differences between the drugs in control of nocturnal gastric acidity." The authors maintained that "ranitidine is about three times more potent than cimetidine," and thus "doubling the bedtime cimetidine dose might be expected to reduce the rate of ulcer recurrence with cimetidine." However, they said they did not know of a direct clinical comparison of bedtime doses of 800 mg and 400 mg cimetidine. They cited two studies in which "twice-daily dosing (200, 300, or 400 mg twice daily) did not improve ulcer relapse rates when directly compared with a single night-time dose (400 mg)." Gough, et al, asserted that unlike provious clinical trials comparing the two drugs, their study was large enough to provide highly statistically significant differences in relapse rates. "In our trial the regular endoscopic examinations provided an accurate picture of ulcer recurrence, because we detected symptomless ulcer relapse; these would be overlooked in trials relying on symptomatic recurrence and endoscopic examination only at the end of the trial, since H-antagonists relieve symptoms, and might be missed altogether if the ulcers rehealed before the trial ended." The British authors noted that an as yet unpublished U.S. comparative trial of ranitidine and cimetidine in 126 patients using an identical protocol "confirmed the superiority of ranitidine (150 mg) over cimetidine (400 mg) as duodenal ulcer prophylaxis with respective ulcer relapse rates" of 16% and 43% (p<0.01) after one year.
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