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The ASTM E1589 method is designed to evaluate the ability of first-aid antiseptic formulations to reduce or suppress the growth of normal skin flora. This method typically compares the activity of one first-aid product against a vehicle control formulation and baseline control site. Skin sites on subjects are treated simultaneously under controlled conditions. Prior to testing, test sites are occluded (typically for 48 hours) to increase the microbial populations of the skin. A "cup scrub" technique is used to collect microbial samples from the study subjects. Significant reduction in the number of microorganisms from the baseline level demonstrates the products antimicrobial efficacy. Comparisons may be made between the performance of the test article and the performance of the vehicle control or reference control (which may be included upon sponsor request).
This test is conducted using the forearms of healthy study participants who have abstained from using antimicrobial products for at least two weeks prior to testing. Following this wash out period, occlusive plastic wrap patches are secured on the mid-volar surface of subject forearms. This occlusion of the test area is performed to increase normal skin flora populations by maintaining moisture and heat in the area, thus providing a suitable microbial challenge to the product(s) under evaluation.
After the occlusion period is complete, forearms are allowed to dry and three testing sites are selected along the volar region of the forearm for sampling. Sampling is performed step-wise, with each site exposed to one of three treatments (baseline recovery, the vehicle control, or the test article) for 30 minutes, followed by sampling via the "cup scrub" technique. This procedure is performed until all treatments have been applied and sampled accordingly. Suriving microorganisms post-treatment are enumerated using standard microbiological plating techniques.
The effectivess of the first-aid antiseptic under evaluation is determined by comparing the number of microorganisms recovered from the testing site after application of the test article, to the number of microorganisms recovered from the baseline test area as well as the vehicle control site and/or reference control site (if included in the study design).