An update on nanocarriers for follicular-targeted drug delivery for androgenetic alopecia topical treatment.

INTRODUCTION: Androgenic alopecia is a multifactorial disease with a high incidence and a great psychological burden on patients. The current FDA-approved treatment is topical minoxidil or oral finasteride. However, both present significant limitations. While the systemic absorption of finasteride causes serious sexual side effects, minoxidil's low solubility imposes a challenge in obtaining a non-irritative and effective formulation. One way to solve such limitations is by using nanocarriers targeting the drug delivery to the hair follicles upon topical application. AREAS COVERED: Here, we review which advancements have been made to achieve a more effective treatment for androgenic alopecia, focusing on nanocarriers for the topical drug delivery systems developed to target hair follicles. EXPERT OPINION: The results from multiple reviewed studies demonstrate the potential of incorporating drugs into different nanocarriers to improve follicular targeting in drug delivery for androgenic alopecia treatment. However, many studies fail to perform the proper controls. Most studies also do not quantify the drug accumulation in all skin layers, especially in hair follicles, which avoids comparisons between different nanocarriers and, hence, reliable conclusions. Future experiments with a broader nanocarrier size range, suitable skin models and controls, and clinical tests to assess the safety of developed formulations will improve the androgenic alopecia treatment.