Background:
Several contact allergens are also irritants. The ideal test preparation should not miss cases of contact allergy and should be nonirritant. The purpose of this study was to compare the skinirritating potential of various propylene glycol (PG) preparations using the objective, noninvasive laser Doppler technique. Previous studies show that the naked eye is not sensitive enough for this comparison.
Methods:
PG was applied under occlusion on the volar forearms of healthy subjects for 48 hours. The test sites were measured with laser Doppler flowmetry before and repeatedly after removal of test patches.
Results:
Slight erythema was observed at two sites exposed to 100% PG. All of the test preparations caused a transient increase in skin blood flow. For PG in water, a dose-response relationship was established. Five percent PG in petrolatum did not cause any increase in blood flow compared with 20% PG in water. The difference was statistically significant.
Conclusions:
Five percent PG in petrolatum seems preferable to avoid irritancy, but it remains to be shown that this preparation is at least as efficient for detecting contact allergy. The present experimental design is recommended for other allergens with suspected irritant properties.
