The chamber vasoconstrictor assay. i. comparison with occluded and unoccluded tests using four corticosteroids

A comparison was made, using the vasoconstrictor assay, between a chamber test and patch tests in which the patch was either covered by an aluminium foil or left unoccluded. The unoccluded patch method produced an obviously less intense degree of pallor than the other methods. With the same test substances the chamber and the aluminium paper occlusion caused equally intense vasoconstriction. The chamber proved to have the following advantages over the aluminium foil method: (1) Test substance did not leak outside the test area, and therefore the pallor was clearly outlined and easier to define. (2) The chamber requires a smaller test area of skin. Of the test substances, clobetasol‐17‐propionate was unquestionably the most effective in the vasoconstrictor tests. Hydrocortisone‐17‐butyrate and betamethasone‐i7‐valerate were about equally effective. The skin blanching activity of hydrocortisone was the weakest of all.