Minoxidil is a potassium channel opener with selective vasodilation effects, and research on it is also hot because it can reduce or stop hair loss and promote hair regeneration.
Hair loss is a common skin disease. The hair growth cycle can be roughly divided into three stages: growth phase (2-6 years), regressing phase (3 weeks), and resting phase (2-3 months). Under normal circumstances, about 50-100 hairs fall out in the regressing phase every day. Then new hair begins to grow in the hair follicles and the cycle begins again.
There are many causes of hair loss, and based on the severity and pathogenesis of the disease, hair loss is divided into two types - scarring and non-scarring. Scarring alopecia is often caused by an inflammatory process caused by trauma, disease, etc. The inflammatory reaction triggers the degeneration of the follicle structure, causing the hair follicle epithelium to be irreversibly replaced by fibrotic tissue. Non-Scarring Alopecia Non-Scarring Alopecia is caused by reduced or slowed hair growth. This article will mainly introduce the drug treatment methods for different types of hair loss, and introduce some new drug delivery methods for the treatment of hair loss.
Medical treatments for hair loss include oral prescription medications such as corticosteroids, immunotherapy inhibitors, and finasteride, and topical medications such as minoxidil. In addition, there are some surgical treatments such as hair transplantation, platelet-rich plasma (PRP) injection, low-intensity laser treatment, etc. In current treatments, patients are usually advised to use topical and oral medications to treat hair loss. Minoxidil and finasteride are currently approved for marketing.
Drug delivery for hair loss treatment includes oral and topical administration. Topical administration is usually preferred because it reduces the risk of adverse side effects of systemic administration and improves patient compliance.
Achieving effective treatment results requires delivering the appropriate drug to the effective site. The scalp is also a part of human skin, and hair follicles are the most effective sites for local drug penetration. Therefore, there are two main strategies to improve the efficiency of transdermal drug delivery: (1) increase the retention time of drugs; (2) improve drug permeability. The research direction focuses on new drug delivery systems that enhance skin penetration and hair follicle targeting, mainly including microneedles, electrophoresis, radiofrequency and nanoparticles. These new drug delivery methods can not only deliver therapeutic drugs such as minoxidil, but also activate the Wnt/β-catenin signaling pathway to treat hair loss.
1. Microneedle therapy
Microneedling is a common method used for skin rejuvenation and treatment of wrinkles and scars. Microneedling is usually solid, hollow, coated or dissolved microneedles and can be modified by varying the depth of penetration and/or the number of microneedles, and achieve optimal depth of scalp delivery between 1.2 and 1.5mm.
The hollow microneedle technology under current research is to inject a small amount of minoxidil-finasteride mixture solution into specific parts of the skin through microneedles. The advantage of this technology is that it allows for uniform and uniform delivery into the skin.
There are also dissolving microneedles (DMN), which are microneedles made of dissolvable polymers encapsulating drugs. When the needle is inserted into the skin and completely degrades, the drug is released into the skin. In some recent scientific research reports, valproic acid-coated dissolving microneedles were used in mice to upregulate the expression of the Wnt/β-Catenin pathway and induce hair regeneration.
2. Ultrasonic electrophoresis
Ultrasound waves can be applied to the skin to increase its permeability and to deliver various drugs. Low-frequency ultrasound (20 KHz) enhances the transport of various low-molecular-weight drugs as well as high-molecular-weight protein drugs through human skin.
Intradermal injection of methylprednisone ointment and cyclosporine solution is a new treatment method for alopecia areata. After 10 minutes of sonophoresis (25 kHz), the drug was applied three times a week for three months, and significant hair regrowth was observed compared to traditional administration.
3. Radio frequency technology
Radiofrequency (RF) uses microelectrodes to pass alternating current through the skin at a frequency of 100–500 kHz. A study on male androgenic alopecia found that using radiofrequency microneedle and 5% topical minoxidil for combined treatment, after 5 months of treatment, the number and thickness of hair in the combined treatment group were significantly higher than those in the single treatment group.
4. Nano drug delivery technology
Nano drug delivery system refers to a drug delivery method that carries nanometer-sized drug particles, including liposomes, solid lipid nanoparticles, nanoemulsions, etc., to a special part (hair follicle).
Nanoparticles improve drug permeability, promote drug absorption, reduce systemic adverse reactions, and reduce skin irritation.
Taking minoxidil nanoparticles as an example, minoxidil nanoformulations have been extensively studied in animals. After minoxidil-encapsulated poly(L-lactide-co-glycolide) nanoparticles were For transdermal administration, delivery efficiency can be increased 2.5 times compared to standard minoxidil solution.
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Reference
- Novel drug delivery approaches for the management of hair loss. Expert opinion on drug delivery, 2020,17(3):287-295.
