Clinical and pharmacological effectiveness of cimetidine in duodenal ulcer patients

The plasma concentration of cimetidine was measured in 40 patients with duodenal ulcer after an oral dose of 200 mg cimetidine. The peak plasma concentration was on average 1.33 mg x 1(-1) (S.D. = 0.53) and the area under the plasma concentration curve (AUC) between 60 and 120 min after cimetidine was 1.13 mg x h x 1(-1) (S.D. = 0.48). The percentage inhibition (I%) of maximal acid output (MAO) to pentagastrin during this 60-min period was 49% (S.D. = 19) with a very low, but statistically significant, correlation with the AUC, r = 0.35 (p less than 0.05), thus demonstrating a very great individual variation in sensitivity to cimetidine. In 37 of the patients the time from start of treatment with cimetidine, 1.0 g/day, to disappearance of ulcer symptoms could be assessed, and it was found that neither the individual sensitivity to cimetidine, I%/AUC, nor the gastric secretory capacity, MAO, correlated significantly with the clinical effectiveness of the cimetidine treatment, although 8 patients with a low sensitivity to cimetidine and a high MAO improved more slowly (28 days) than the other 29 patients (13 days) (p less than 0.1).