Cytotoxic, cytostatic, and keratolytic activity of anti-dandruff shampoo formulations

Abstract

Background: Dandruff is characterized by increased sebum production, yeast colonization, and hyper-keratinization leading to an itchy-flaky scalp. Ancillary non-microbial reasons for flaky scalp include ultraviolet rays and excessive heat from the sun. Thus, apart from traditional anti-fungal activity, anti-dandruff formulations should also possess the keratolytic activity and should be safe to use. Methods: Selsun, a shampoo formulation with 2.5% selenium sulfide (SS2.5), was tested in-vitro for its cytotoxic and cytostatic activities via cell viability of primary human dermal fibroblasts (HDFs). Its keratolytic activity was determined by assessing anti-proliferative activity on immortalized human keratinocyte (HaCaT) cell line. The shampoo was compared with 3 other shampoo formulations, one containing 2% ketoconazole (K2), second containing 2% ketoconazole with 1% zinc pyrithione (K2ZP1), and third containing 1% zinc pyrithione (ZP1). Results: Of the tested samples, SS2.5 and K2ZP1 showed cytostatic and keratolytic activity where the IC50 values on normal HDFs i.e., 0.521 mg/ml and 0.220 mg/ml, respectively, were higher than those on HaCaT cells (0.162 mg/ml and 0.198 mg/ml, respectively). SS2.5 displayed the highest keratolytic activity at IC50 of 0.162 mg/ml, followed by K2ZP1 (0.198 mg/ml) and K2 (0.267 mg/ml). On normal HDFs, SS2.5 showed the highest IC50 value (0.521 mg/ml), followed by K2 at 0.264 mg/mL, K2ZP1 at 0.220 mg/ml, and ZP1 at 0.139 mg/ml. Conclusions: SS2.5 was found to possess the highest cytostatic and keratolytic activities among all the shampoo formulations tested, thereby confirming its safety profile.