Efficacy and Acceptability of a New Water-Soluble Nail Strengthener Containing Pistacia lentiscus and Hyaluronic Acid to Improve the Appearance of Brittle Nails versus Untreated Nails: In vitro and Clinical Evidence.

Introduction: Brittle nail syndrome is characterized by dry, weak, easily breakable nails that show inelasticity, splitting and overall nail plate fragility. Objective: This paper describes in vitro and clinical studies using bovine hooves designed to assess the efficacy, compatibility and acceptability of a water-soluble nail strengthener (WSNS), containing Pistacia lentiscus and hyaluronic acid, for the treatment of patients affected by brittle nails. Methods: In the in vitro study, the WSNS was tested versus placebo and a marketed product on bovine hoof membranes, applied once daily for 14 days for evaluation of firmness, viscoelasticity and thickness before and after applications. In a clinical study, 23 female subjects affected by brittle nails were included, and the WSNS was applied once daily for 3 months. Signs and symptoms were rated by the investigators and by the participants during treatment at 28 and 84 days with different methods and dermoscopic images. Subjective efficacy was evaluated by specific questionnaires. Results: In the in vitro study, the daily application of the WSNS and marketed product led to a significant increase in firmness index. In the clinical study, the nails on the treated hand presented an improvement in nail appearance and weakness, after 28 and 84 days of WSNS application, respectively. The nails not treated showed no improvement. The WSNS was well tolerated. Conclusions: The WSNS containing Pistacia lentiscus and hyaluronic acid was shown to significantly increase nail firmness in the in vitro study. In the clinical study, WSNS significantly improved brittle nail appearance. The hydrosolubility and easy-to-apply format of WSNS were reported to be factors of a good compliance. We consider this product as an important tool to improve and reinforce the aspect of brittle nails.