In-Vitro Release of Zinc Pyrithione from A Shampoo Base and the Effects of Various Additives on its Release Rate

Abstract

Zinc pyrithione has been established as one of the most effective anti-dandruff ingredients for use in shampoo formulations, through various clinical studies. However, the clinical efficacy is dependent upon its release rate from the vehicle and adsorption onto the scalp and hair. In light of these findings, the release of zinc pyrithione from a typical lotion shampoo base was investigated in-vitro. The shampoo formulation consisted of an anionic detergent, an amide and thickening agents commonly used in such products. The additives used included ethanol, dimethylsulfoxide (DMSO), polyethylene glyeol-400, propylene glycol and urea at 5%, 10% and 15% by weight of the formulations.

Release experiments were carried out at 37°C, with diffusion cells immersed in beakers containing distilled water adjusted to pH 5.

In general, the presence of the additive ingredient increased the release of zinc pyrithione. Among the samples evaluated, the formulations containing ethanol or propylene glycol gave the highest release rate of the drug. And the rank order for the release of the zinc pyrithione was observed to be from the samples with ethanol > dimethyl sulfoxide > urea > polyethyleneglycol-400 > propylene glycol > commercial products.