Fares*, H.M., Chatterjee, S., Hayward, M. SmithKline Beecham Consumer Healthcare, 1500 Littleton Road, Parsippany, NJ 07054.

Two in vitro models to measure release of benzoyl peroxide (BPO) from formulations were presented. Franz-type diffusion cells and acetonitrile/water receptor mediums were used in both models. The barrier in one model was silicone sheeting and in the other was cultured human epidermis. The similarity in release profiles, rates of permeation, and diffusion coefficients obtained provided enough evidence to demonstrate that the two models were comparable. An in vitro model to study the irritation of formulations containing BPO was also presented. The model used cell viability as a measure of irritation. Tissue viability was assessed using the MTT test after 5, 19, and 27 hours exposure. The effective time where 75% of the keratinocytes remain viable in the skin model (ET75) was used as a measure to compare formulations. ET75 decreased as the concentration of BPO increased in the formulations. Values of ET75 were lower in vanishing formulations than in tinted formulations with the same level of BPO. Cell viability was linearly related to the rate of release of BPO. The higher the release rate, the lesser was the time needed to reach the ET75. This indicated that the amount of BPO delivered from the vehicle was the primary cause of irritation.


Barrier properties formation, Benzoyl peroxide, Cutaneous irritancy, Cutaneous irritation, Cutaneous toxicity, Dermal absorption, Dermal irritancy, Dermal irritancy testing, Dermal irritation, Dermal penetration, Dermal permeation, Endpoints, MTT, EpiDerm, MTT, MTT ET-50 tissue viability assay, MTT assay, Percutaneous absorption, Percutaneous penetration, Permeation, Skin irritancy, Skin irritation, Skin models, cultured, Transdermal, Viability

Request a copy of this paper, click here.