Nanocarriers for topical minoxidil in androgenetic alopecia: systematic review of preclinical and clinical evidence.

BACKGROUND

Androgenetic Alopecia (AGA) is the most prevalent hair disorder. Conventional topical minoxidil is limited by suboptimal follicular penetration, local adverse effects, and poor adherence; nanocarrier-based "nanominoxidil" systems may optimize delivery, but their clinical value remains uncertain.

OBJECTIVE

To synthesize experimental and clinical evidence on nanocarrier-based topical minoxidil for AGA.

METHODS

We systematically searched databases (2015-2024) for in vitro, ex-vivo, in vivo, and human studies evaluating nanocarriers < 1000 nm loaded with minoxidil versus conventional minoxidil, placebo, or no treatment. Primary outcomes were follicular and cutaneous penetration or retention; secondary outcomes included hair length, density and/or coverage, biomarker modulation, adverse events, and formulation stability. Risk of bias was assessed with SYRCLE and OHAT.

RESULTS

Of 410 records, 20 studies met eligibility criteria, predominantly preclinical, and one evaluated cutaneous tolerability in healthy volunteers. Across platforms (lipid, polymeric, hybrid and deformable systems, nanoemulsions), nanominoxidil consistently increased follicular deposition and cutaneous retention (≈2- to > 7-fold vs conventional solutions) and improved hair growth surrogates and angiogenic or stem-cell markers. Local tolerability was generally acceptable and systemic exposure was negligible when reported.

STUDY LIMITATIONS: Evidence is preclinical, with a single non-therapeutic human study; heterogeneity across models, comparators, doses, follow-up, and outcomes, and frequent lack of randomization, blinding, and standardized safety reporting, precluded meta-analysis and limited internal validity and generalizability.

CONCLUSIONS

Nanotechnology-based minoxidil formulations enhance follicular targeting and hair-growth surrogate outcomes in experimental models and appear locally safe, but randomized trials in patients with AGA are required before nanominoxidil can be recommended for routine clinical use.