P10 Comparison between mild irritant response in hairless guinea pigs and human volunteers

Abstract

Small rodent laboratory animals lack the complex cutaneous structure and function of human skin resulting in “all or none”‐responses to mild irritants so that the animals may show a less discriminative reaction pattern compared to human volunteers when studying the tolerability of topical drug formulations. This study compared the tolerance pattern of a 6 composite formulations (SCF A‐F) in human volunteers and in hairless guinea pigs (HLGP). The formulations were 2 basic creams (A and B) and 4 composite creams containing either isopropyl palmitate (C), glycerin (D), canola oil (E) or (‐)‐alfa‐bisabolol (F). The tolerability of 6 selected skin care formulations (SCF A‐F), known to cause a differentiated irritative response in HLGP, was studied in 15 male SGP and 20 human volunteers. The HLGP were treated twice a day on a 5 × 5 cm area on each flank with a SCF for 4 consecutive days. The irritant effects of the SCF were quantified by clinical assessment, measurement of trans epidermal waterloss (TEWL) and colorimetry (a*‐parameter). In humans the tolerability was evaluated clinically using the chamber scarification test. In HLGP SCF A and C were strong irritants followed closely by E, the remaining formulations were indistinguishable. In human volunteers all formulations were tolerated equally and well with the clinical score rising slightly on the first day and remaining stable thereafter. In conclusion, the HLGP appeared to be too sensitive, as formulations showing irritation in HLGP were well tolerated in a human.