Preparation of Zinc Pyrithion Lotion as a Hospital Preparation and Evaluation of its Physical Characteristics.

In order to treat psoriasis, many kinds of drugs are administered systemically and topically. However, the topical admimistration of drugs is preferred to the systemic administration because the former can occasionally cause serious side effects. Zinc Pyrithione (ZPT), which is recognized as an active ingredient in a major anti-dandruff shampoo, was introduced as a new antipsoriatic agent. In this study, ZPT lotions as a hospital preparation were prepared for topical administration.Hydroxypropylcellulose-H (HPC), sodium-polyacrylate (PANA) and carmellose sodium (CMC) were used as a suspending agent of 0.5% ZPT lotion. The following physical characteristics, the viscosity, the osmotic pressure, the sedimentation, the microscopic view and the dispersion were investigated in each ZPT lotion containing different suspended agents.The viscosity of the ZPT lotion with HPC and CMC increased with the additive ratio of these suspended agents. On the other hand, the viscosity of the ZPT lotion with PANA increased logarithmically with its additive ratio. The low osmotic pressure of each lotion was expected to be less irritable in clinical application. When ZPT lotions were stored at room temperature for 14 days, the lotion with HPC or CMC showed free sedimentation and caking of the particles. In contrast, the lotion with PANA showed a growth of particles by a microscopic analysis and coagulated sedimentation by macroscopy. These phenomena may be due to the ionic intensity of the solution and the interaction between ZPT particles. The dispersion time of ZPT lotions with PANA was shorter than those with HPC or CMC.Based on our findings, 0.2% PANA was found to be preferable to HPC and CMC as the suspended agent in ZPT lotion.