17955 Comparison of SPF50+ and SPF100+ sunscreens on the induction of cutaneous pigmentation over multiple days: A real-world, single-center, randomized, double-blinded evaluation

Recently, a study evaluating the difference in sunburn protection offered by SPF 50+ and SPF 100+ sunscreens over the course of 5 consecutive days in a beach environment facilitated a unique opportunity to evaluate the protection sunscreens provide against the induction of cutaneous pigmentation. A randomized, double-blinded, split body/face study assessing the efficacy of two broad spectrum sunscreens (SPF50+ and 100+) was conducted in the beach setting of St Petersburg, Florida. Fifty-five healthy subjects (1 phototype I, 22 phototype II, and 32 phototype III; average age 45.2 years [range: 19-59]) were enrolled. Subjects were permitted unrestricted access to test sunscreens and instructed to apply to the designated side as they normally would. Objective assessments of daily and cumulative changes in cutaneous pigmentation were conducted by colorimetry (ΔL*, Δb*, ΔITA°) and diffuse reflectance spectroscopy (DRS) (Δ melanin). SPF 100+ sunscreen offered greater protection against pigmentation induction as determined by a lower ΔL* and an increased Δb* on the SPF 50+ treated side (P \u3c.001), which resulted in a mean ΔITA° of −7.57 on the SPF 50+ side and −5.78 on the SPF 100+ side. This pigmentation differential was supported by DRS assessments indicating greater melanin induction on the SPF 50+ side, Δ melanin (SPF50+ 0.18 ± 0.09 vs SPF100+ 0.15 ± 0.09, P =.01). Although pigment formation occurred on both sides, compared with SPF 50+ sunscreen, objective assessments show that the SPF 100+ sunscreen offered significantly greater protection against the induction of cutaneous pigmentation in actual use