Efficacy and Safety Trial of Using Ultra-Pulsed Shockwaves to Deliver Tranexamic Acid for the Treatment of Melasma

Melasma is a common, chronic, acquired facial pigmentation disorder, also known as chloasma. Clinically, it presents as symmetrical, unevenly pigmented light to dark brown patches on the cheeks, forehead, and jawline with indistinct borders. The prevalence among Asian women of childbearing age can be as high as 30%, and it tends to recur and is difficult to cure.

The pathogenesis of melasma is not fully understood, but genetic susceptibility, sunlight exposure, and hormonal changes are considered the three major contributing factors. Increased melanin synthesis, vascular proliferation at skin lesions, inflammation, and impaired skin barrier all play roles in the development of melasma.

Melasma is clinically staged as active or stable phase. Clinical subtypes of melasma are categorized based on vascular involvement into 2 types: pure pigment type (M-type) and pigment combined with vascular type (M + V type). This classification guides the selection of treatment drugs and methods. According to the location of pigmentation, it is classified into 2 types: epidermal type (increased epidermal pigmentation) and mixed type (increased epidermal pigmentation + dermal superficial melanocytes). This classification is useful for determining treatment efficacy.

In the Expert Consensus on Phototherapy and Repair of Melasma (2020 edition), it is suggested that systemic medication is not the first choice for treating melasma and is mostly used off-label. Intravenous administration is effective, and oral administration is generally less effective. Common regimens include vitamin C, glutathione combined with vitamin C, and intravenous tranexamic acid. Oral tranexamic acid has some efficacy.

The Expert Consensus on the Diagnosis and Treatment of Melasma in China (2021 edition) states that single or repeated phototherapy can lead to pigment deposition, pigment reduction/loss, and recurrence, thus phototherapy is not recommended as a long-term clinical maintenance approach. The number of consecutive phototherapy treatments should not exceed 15 times, and repeat treatments can be considered after a 1-year interval. Topical medication is the preferred treatment: 1. Photoprotective agents, routinely combined with antioxidants; 2. Hydroquinone and its combination therapy are the most thoroughly researched topical medications. Adverse reactions include skin irritation, allergic contact dermatitis, and rarely, ochronosis; 3. Non-hydroquinone topical medications: retinoic acid, tranexamic acid, kojic acid, mequinol, arbutin, licorice extract, niacinamide, etc., most of which are also tyrosinase inhibitors.