Response to pentagastrin in Man. IV. Dose-response characteristics.

An analysis has been made of the gastric response of 7 individuals to a set of 5 dose rates of pentagastrin, given on different days or in sequence on the same day, in order to identify constraints on the use of secretory data in determining 'kinetic constants', such as ED50 or CMR. It has been shown that errors arise from the use of near-threshold doses of pentagastrin; too short periods of stimulation, and variant responses to pentagastrin. We conclude that values of ED50 are best considered as only qualitative, rather than quantitative, indices of sensitivity to pentagastrin.