Assay of Cation-Active Antiseptics

Abstract

The agar-plate or the cylinder-plate method of testing the effectiveness of antiseptics and antibiotics is now a well-known laboratory technique; and it is the basis of quantitative estimations of penicillin and of other antiseptics. There is little doubt that the degree of ‘zoning’ obtained is an excellent criterion of a good chemotherapeutic agent, and Fleming¹ considers that this test should be so applied. However, recent experiences in my laboratory indicate that this test is not necessarily a good criterion for cation-active antiseptics of the class of quaternary ammonium salts, such as cetyl trimethyl ammonium bromide (‘Cetavlon’) and cetyl pyridinium ohloride (‘Ceepryn’).