Evaluation of sensory irritation caused by topical medications using a novel technique

Topical medications are often the first line therapy utilized by dermatologists for a variety of conditions. However, a common side effect of topical medications is application site irritation. The aim of this study was to evaluate and compare the sensory irritation caused by hydrocortisone butyrate lipocream 0.1% using a non-invasive and inexpensive technique.

Twenty participants with corticosteroid-responsive dermatoses were enrolled. Three target areas of unaffected skin were abraded. A negative control (petrolatum ointment), a positive control (an over-the-counter [OTC] anti-itch preparation containing benzyl alcohol), and a test product (hydrocortisone butyrate lipocream 0.1%) were each applied to separate target areas on the legs. Participants rated the irritation of each target area using a 10-point scale (1 [no symptoms] to 10 [intolerable burning/ stinging requiring removal of the medication]).

The mean irritation scores for petrolatum ointment, the OTC anti-itch preparation, and hydrocortisone butyrate lipocream 0.1% were 1.30, 5.70, and 1.95, respectively. The difference in irritation between the OTC anti-itch preparation and hydrocortisone butyrate lipocream 0.1% was highly significant (P < 0.0001). The difference in irritation between the OTC anti-itch preparation and petrolatum ointment also was highly significant (P < 0.0001). The difference in irritation between hydrocortisone butyrate lipocream 0.1% and petrolatum ointment also was statistically significant (P = 0.0265). Irritation scores were then standardized on a 10-point scale, with the irritation score of the negative control given a value of 1.00 and the irritation score of the positive control given a value of 10.00. The standardized irritation score of the test product, hydrocortisone butyrate lipocream 0.1%, was calculated to be 2.33.

Our study, using a novel technique to measure sensory irritation, establishes hydrocortisone butyrate lipocream 0.1% to be minimally irritating. We hope to use this simple and easy-to-use assay to measure and compare the severity of the sensory irritation of various commercially available topical preparations. In doing so, we hope to ultimately create a sensory irritation ranking scale, which would enable physicians to choose less irritating products, thereby enhancing adherence to treatment regimens and patient satisfaction.