4-n-Butylresorcinol, a resorcinol derivative, inhibits both tyrosinase and tyrosinase-related protein-1 (TRP-1). Hypopigmenting action of 4-n-butylresorcinol was first reported in 1995, and subsequent in vitro and in vivo studies have documented its hypopigmenting efficacy. In the MelanoDerm skin model culture, 4-n-butylresorcinol has proven to be the most potent hypopigmenting agent when compared to kojic acid, hydroquinone, and arbutin. Furthermore, the biochemical assay on inhibition of human tyrosinase activity has revealed the superiority of 4-n-butylresorcinol over other hypopigmenting agents.6
In a study, Okubo et al7 reported the inhibitory effect of 4-n-butylresorcinol on cultured B16 melanoma cells and established the role of 4-n-butylresorcinol on tyrosinase activity with no cytotoxicity. This paved the way for newer in vivo studies which established more evidences on the activity of both tyrosinase and TRP-1.7
Numerous in vivo and in vitro studies, biochemical assays, and clinical studies show 4-n-butylresorcinol to be very potent, effective, and safe in melasma. However, all the published studies of 4-n-butylresorcinol have shown the hypopigmenting efficacy, safety, and tolerability with the 0.1% cream, but there is paucity of clinical studies that used the 0.3% cream. Furthermore, ethnic differences in skin reactivity have been explored through the years, leading to the clinical hypothesis that Asian skin is more reactive than black skin and Caucasian skin.8 Considering these, and the fact that 4-n-butylresorcinol 0.3% cream is available for the first time in India, we explored the efficacy, safety, and tolerability of 4-n-butylresorcinol 0.3% cream in Indian patients with melasma.
Materials and methods
A multicentric, open-label, single arm study was conducted in two premier medical colleges of Bangalore, India. The study centers were Dermatology Departments of Dr BR Ambedkar Medical College and Kempegowda Institute of Medical Sciences, Bangalore, India.
This study was conducted according to the protocol and in accordance with ethical guidelines. The study was conducted at each trial site after receiving approval from the KIMS Institutional Ethics Committee, Bangalore and the Institution Ethics Committee, Dr. B.R. Ambedkar Medical College, Bangalore. The study was registered in Clinical Trial Registry of India (CTRI) (CTRI/2015/04/005697).