Estrogenic activity of zinc pyrithione: an in vivo and in vitro study

Zinc pyrithione (ZP) is commonly used to prevent dandruff and seborrheic dermatitis. Many consumers are exposed daily to high doses of ZP, causing serious concerns about its toxicity. The reproductive and developmental toxicities were previously reported in pregnant rats. However, the estrogenic activity of ZP at varying degrees of exposure has been rarely studied. Thus, we performed an uterotrophic assay, E-screen assay, and gene expression profiling to assess the estrogenic activity of ZP. For the uterotrophic assay, ZP (2, 10, or 50 mg/kg/d) was subcutaneously administered to ovariectomized rats every day for three days. Uteri were extracted 24 hours after the last dose. Then, wet and blotted uterine weights were measured. For the E-screen essay, MCF-7 cells (a breast cancer cell line) were exposed to 10⁻⁹ to 10⁻⁶ M of ZP, and cell proliferation was then measured. For the gene expression analysis, changes of gene expression levels in uterine samples taken for the uterotrophic assay were analyzed. In the uterotrophic assay, the concentration of ZP had no significant effect on uterine weight. In the E-screen assay, ZP at any concentration showed no significant increase in MCF-7 cell proliferation, compared to the control group. However, 10⁻⁶ M of ZP significantly reduced cell viability. The changes in gene expression slightly differed between the ZP and control groups. The in vivo and in vitro assays, together with gene expression analysis, demonstrated that ZP showed no significant estrogenic activity.

Estrogenic activity of zinc pyrithione: an in vivo and in vitro study

Zinc pyrithione (ZP) is commonly used to prevent dandruff and seborrheic dermatitis. Many consumers are exposed daily to high doses of ZP, causing serious concerns about its toxicity. The reproductive and developmental toxicities were previously reported in pregnant rats. However, the estrogenic activity of ZP at varying degrees of exposure has been rarely studied. Thus, we performed an uterotrophic assay, E-screen assay, and gene expression profiling to assess the estrogenic activity of ZP. For the uterotrophic assay, ZP (2, 10, or 50 mg/kg/d) was subcutaneously administered to ovariectomized rats every day for three days. Uteri were extracted 24 hours after the last dose. Then, wet and blotted uterine weights were measured. For the E-screen essay, MCF-7 cells (a breast cancer cell line) were exposed to 10⁻⁹ to 10⁻⁶ M of ZP, and cell proliferation was then measured. For the gene expression analysis, changes of gene expression levels in uterine samples taken for the uterotrophic assay were analyzed. In the uterotrophic assay, the concentration of ZP had no significant effect on uterine weight. In the E-screen assay, ZP at any concentration showed no significant increase in MCF-7 cell proliferation, compared to the control group. However, 10⁻⁶ M of ZP significantly reduced cell viability. The changes in gene expression slightly differed between the ZP and control groups. The in vivo and in vitro assays, together with gene expression analysis, demonstrated that ZP showed no significant estrogenic activity.

Clinical Evaluation of a New-Formula Shampoo for Scalp Seborrheic Dermatitis Containing Extract of Rosa centifolia Petals and Epigallocatechin Gallate: A Randomized, Double-Blind, Controlled Study

BACKGROUND: Scalp seborrheic dermatitis is a chronic type of inflammatory dermatosis that is associated with sebum secretion and proliferation of Malassezia species. Ketoconazole or zinc-pyrithione shampoos are common treatments for scalp seborrheic dermatitis. However, shampoos comprising different compounds are required to provide patients with a wider range of treatment options. OBJECTIVE: This study was designed to evaluate a new-formula shampoo that contains natural ingredients-including extract of Rosa centifolia petals and epigallocatechin gallate (EGCG)-that exert antioxidative, anti-inflammatory, and sebum secretion inhibitory effects, and antifungal agents for the treatment of scalp seborrheic dermatitis. METHODS: Seventy-five patients were randomized into three treatment groups; new-formula shampoo, 2% ketoconazole shampoo, and 1% zinc- pyrithione shampoo. The clinical severity scores and sebum levels were assessed by the same dermatologists at baseline (week 0), and at 2 and 4 weeks after using the shampoo. User satisfaction and irritation were also assessed with the aid of a questionnaire. RESULTS: The efficacy of the new-formula shampoo was comparable to that of both the 1% zinc-pyrithione shampoo and the 2% ketoconazole shampoo. Furthermore, it was found to provide a more rapid response than the 1% zinc-pyrithione shampoo for mild erythema lesions and was associated with greater user satisfaction compared with the 2% ketoconazole shampoo. However, the new-formula shampoo did not exhibit the previously reported sebum inhibitory effect. CONCLUSION: Extract of R. centifolia petals or EGCG could be useful ingredients in the treatment of scalp seborrheic dermatitis.

Clinical Efficacy for 1% Zinc Pyrithione Shampoo for the Treatment of Dandruff / 대한피부과학회지

BACKGROUND: Dandruff is a common complaint, and is suffered by up to 50% of the population at some time. Malassezia yeasts, which comprise part of the normal skin flora, might be a critical factor in this disease, as they have been found in higher proportions in patients with seborrheic dermatitis or dandruff, its milder form. OBJECTIVE: The aim of this study was to evaluate the clinical efficacy of 4 weeks of treatment with 1% zinc pyrithione (ZP) shampoo. METHODS: A randomized, double-blind, 4-week treatment period was preceded by a 1-week run-in period. A total of 30 patients were enrolled in this study. Assessments included the patient's subjective score (PSS) and the investigator's assessment score (IAS), images of the affected scalp area, the severity of sebum production, and the erythema and moisturizing effect of the shampoo. RESULTS: 1% ZP shampoo significantly reduced the extent and severity of scaling, as measured by folliscope imaging on visit 2 (p=0.0391) and visit 3 (p=0.0381), as well as pruritus related to the disease as measured by the grading systems, PSS (p=0.0352) and IAS (p=0.0142). Additionally, the results of this study show that a treatment regimen with 1% ZP shampoo significantly reduced scalp sebum production as measured by a sebumeter. Erythema measured by the chromameter was not as meaningful. The corneometric values were slightly increased in the group treated with 1% ZP shampoo but not in the group treated with ZP-free shampoo. Side effects of the ZP shampoo were quite mild and tolerable, and were observed only in a small group of patients. CONCLUSION: 1% ZP shampoo appears to be both effective and well-tolerated when used for the treatment of dandruff.