Botulinum Toxin A for Ultraviolet-Induced Hyperpigmentation Dermatologic Surgery

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• In this double-blind randomized controlled trial, 15 patients with Fitzpatrick skin type III or IV underwent 4 intradermal injections, including 3 varying dilutions of botulinum neurotoxin type A (BoNT-A) and 1 saline control on the abdomen. The abdomen was exposed to broadband UVB at the injection sites 14 days after injection. The physician-evaluated mean lightness index during weekly follow-up was lowest for the BoNT-A 1:5 site (7.64) and highest for the control site (8.49). All BoNT-A treated sites were graded as significantly lighter than the control site (P = .002). Histologic section of Fontana–Masson staining of biopsies obtained at 1-week follow-up demonstrated increased melanin in the control site compared with the BoNT-A–treated sites.

• Intradermal BoNT-A injections were protective against UVB-induced hyperpigmentation, both clinically and histologically.

–  Kelly B. Scarberry, MD

Abstract 

BACKGROUND

Ultraviolet (UV) exposure contributes to skin hyperpigmentation. Recently, botulinum neurotoxin type A (BoNT-A) showed a promising protective effect on UVB-induced hyperpigmentation in both in vitro and animal models.

OBJECTIVE

The study aimed to investigate the preventive effect of BoNT-A against UVB-induced hyperpigmentation in human subjects.

MATERIALS AND METHODS

A prospective, double-blinded, randomized controlled trial was performed in 15 healthy participants. Four separate square areas on the abdomen were randomly injected intradermally with different dilutions of BoNT-A (1:2.5, 1:5, 1:7.5) and normal saline (control). Two weeks after injection, hyperpigmented spots were induced by UVB irradiation at the experimental sites. The lightness index and hyperpigmentation scores from blinded physician and participants were evaluated.

RESULTS

Fifteen participants completed the study. One week after UVB irradiation, all BoNT-A-treated sites had a significantly lower degree of hyperpigmentation than the control site in lightness index and hyperpigmentation scores from blinded physician and participants (p < .05). However, no statistically significant difference was observed between different concentrations of BoNT-A. No side effects were observed throughout the study period.

CONCLUSION

Intradermal BoNT-A injection provided a protective effect from UVB-induced hyperpigmentation. It may be used for other hyperpigmentation disorders that are aggravated by UVB.

Dermatologic Surgery

A Study of Botulinum Toxin A for Ultraviolet-Induced Hyperpigmentation: A Randomized Controlled Trial

Dermatol Surg 2021 May 01;47(5)e174-e178, V Vachiramon, C Kositkuljorn, K Leerunyakul, T Rattananukrom, N Jurairattanaporn 

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Benjamin Hidalgo-Matlock
Skin Care Physicians of Costa Rica

Clinica Victoria en San Pedro: 4000-1054
Momentum Escazu: 2101-9574

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