[Zinc salts in dermatology]

Zinc is an essential trace element for the human organism. It acts like cofactor for the metalloenzymes involved in many cellular processes. Its anti-inflammatory activity, which is the basis of therapeutic use, other than acrodermatitis enteropathica, is not well known: production of cytokines, antioxidant activity. Its toxicity is very low, but marked at high doses during chronic administration by the risk of hypocupremia. It is not teratogenic and can be given during pregnancy. Its absorption, through the duodenum, is inhibited by excessive phytate intake. Maximum concentration is reached after 2 to 3 hours. It is widely distributed in the organism, mainly in muscles and bone. Excretion is predominantly digestive. Its spectacular effect in acrodermatitis enteropathica, through compensation of genetically determined malabsorption was discovered in 1973. Its usefulness in acne is based on the anti-inflammatory action and was first described with zinc sulfate, then with better tolerated gluconate. Many controlled studies have shown an efficacy on inflammatory lesions. Doses varied from 30 to 150 mg of elemental zinc and studies against cyclines have shown that minocycline has a superior effect; but zinc might be an alternative treatment when cyclines are contraindicated. To date we don't have convincing data for its use in other indications (leishmaniosis, warts, cutaneous ulcers). Tolerance at usual doses (200 mg of zinc gluconate or 30 mg of elemental zinc) is good. Major side effects are abdominal with nausea, vomiting, but are fleeting and dose dependent.