Experimental Design
Ethical approval (Ref No: 160614243, 01 July 2016) was obtained from Pharma-Ethics (Pty) Ltd. research ethics committee (Lyttelton Manor, South Africa), in compliance with the 1964 Declaration of Helsinki and its subsequent amendments. The study was conducted in accordance with the FDA’s VCA guidance (22) as described in a previously published study by Zvidzayi et al (26). A 10μL dose of the relevant creams were applied to demarcated sites on the ventral surface of the arms of each subject and left on for the relevant dose durations (i.e. , at 5, 10, 20, 40, 60, 90, and 150 min). The products were removed from the application sites after the relevant dose durations using cotton swabs, 3 wet wipes (warm water) followed by 2 dry wipes. Chromameter (Model CR 400, Minolta®, Osaka, Japan) readings at all sites were taken over 24 h by a single chromameter operator. Only the a-scale data were used in the statistical analysis in accordance with the FDA guidance (17,26–28).