Introduction: Tolerance and clinical efficacy of zinc gluconate are well documented, however, no study have evaluated its photosensitizing potential. It is well known that many treatments of acne are photosensitizing. Evaluation of the photosensitizing potential of zinc gluconate was the aim of this study.
Patients and method: Two open, monocentric studies were carried out with acneic volunteers. The methodology used in this study was an adaptation from that existing for the evaluation of the photosensitizing potential of topical products. In the study of phototoxic potential, volunteers were exposed to 20 J/cm2 UVA and to 0.75 times MED, before and after administration of zinc gluconate. Clinical and colorimetric evaluations of reactions were then carried out 1, 24, 48 and 72 hrs after exposure. In the photoallergic potential study, during the first week of the induction phase, the volunteers were exposed to 2 times MED, and to 3 times the MED during the second and third week. Then during the challenge phase, they were exposed t o4 J/cm2 UVA and to 0.75 times MED. Zinc gluconate was administered throughout the study. Clinical and colorimetric evaluations of reactions were carried out 24, 48 and 72 hrs after exposure, only during the challenge phase.
Results: The majority of clinical scores measured on scales at 6 and 5 levels were equal to 0 and 0.5 (evaluation of the phototoxic potential) or all equal to 0 (evaluation of the photoallergic potential). Thus zinc gluconate did not induce phototoxic or photosensitive reactions, whatever the ultraviolet type used.
Discussion: Since zinc gluconate does not induce any photosensitive reaction, it could be prescribed during periods of exposure to sun.