Optimum dose of histamine for maximal acid output in underweight subjects.

The effects of increasing doses of histamine acid phosphate on the gastric secretion of acid has been studied in a randomized fashion in five normal control and 15 duodenal ulcer subjects. The dose of histamine acid phosphate used in each individual was 40, 70, 76 and 80 mug/kg. and 3.2 mg. of histamine. In 12 of 20 subjects the highest mean +/- S.D. acid output was observed after a dose of 76 mug./kg. body weight. When the acid output was expressed as the percentage of the highest response with different doses of HAP, the response was maximum with 76 mug. kg. dose. Further statistical analysis by rank totals and X2r by Friedman's two-way analysis by ranks also revealed highest acid output after a 76 mug./kg. dose of HAP. These findings suggest that 76 mug./kg. is the optimum dose for maximal acid output in underweight subjects. Only one patient showed highest acid output after a 3.2 mg. dose of histamine. The mean +/- S.D. acid output after 76 mug./kg. was higher than that after a 3.2 mg. dose of histamine. Hence, for estimating maximal acid output, a weight related dose and not a fixed dose is recommended. Further, it was shown that there was significant correlation between PAO and MAO after various doses of histamine in both the groups. Hence, for clinical purposes, estimation of one hourly poststimulatory maximal acid output after a dose of 76 mug./kg. body weight of histamine acid phosphate is recommended for underweight subjects.