Pharmacokinetics of cimetidine in patients with unresponsive duodenal ulcer

The pharmacokinetics of cimetidine after an oral dose of 400 mg were measured in 18 patients with duodenal ulcer, 9 refractory and 9 responders. The peak plasma concentration of cimetidine (2.13 +/- 0.17 micrograms/ml vs 1.43 +/- 0.04 micrograms/ml), the area under the plasma concentration curve (A.U.C.) between 0 to 8 hours after cimetidine (8.49 +/- 0.29 micrograms/ml/h vs 5.83 +/- 0.25 micrograms/ml/h), and the time span in which cimetidine was above 0.5 micrograms/ml (I.C.50) (401 +/- 8.86 min vs 296 +/- 20 min) were all found to be greater in responding patients than in non-responders to the therapy. No differences were detectable between the two groups in urinary excretion, T 1/2 of cimetidine or percentage inhibition (1%) of maximal pentagastrin-stimulated acid output (MAO). The results indicate that clinical healing of duodenal ulcer after cimetidine is related principally to the drug's pharmacokinetics, i.e. to its absorption from the small bowel, and that some other therapeutic approaches might be tried before surgery in cases of duodenal ulcer refractory to cimetidine.