A novel model of inflammatory pain in human skin involving topical application of sodium lauryl sulfate.

OBJECTIVE AND

DESIGN

Sodium lauryl sulfate (SLS) is a known irritant. It releases pro-inflammatory mediators considered pivotal in inflammatory pain. The sensory effects of SLS in the skin remain largely unexplored. In this study, SLS was evaluated for its effect on skin sensory functions.

SUBJECTS: Eight healthy subjects were recruited for this study.

TREATMENT: Skin sites were randomized to topical SLS 0.25, 0.5, 1, 2% and vehicle for 24 h. Topical capsaicin 1% was applied for 30 min at 24 h after SLS application.

METHODS

Assessments included laser Doppler imaging of local vasodilation and flare reactions, rating of spontaneous pain, assessment of primary thermal and tactile hyperalgesia, and determination of secondary dynamic and static hyperalgesia.

RESULTS

SLS induced significant and dose-dependent local inflammation and primary hyperalgesia to tactile and thermal stimulation at 24 h after application, with SLS 2% treatment eliciting results comparable to those observed following treatment with capsaicin 1%. SLS induced no spontaneous pain, small areas of flare, and minimal secondary hyperalgesia. The primary hyperalgesia vanished within 2-3 days, whereas the skin inflammation persisted and was only partly normalized by Day 6.

CONCLUSIONS

SLS induces profound perturbations of skin sensory functions lasting 2-3 days. SLS-induced inflammation may be a useful model for studying the mechanisms of inflammatory pain.