4-n-butylresorcinol

**4-n-butylresorcinol** (Kopcinol) is a synthetic small molecule and a derivative of resorcinol, primarily used as a topical agent for the treatment of hyperpigmentation disorders like melasma. Its main mechanism is potent inhibition of tyrosinase and tyrosinase-related protein-1 (TRP-1), key enzymes responsible for melanin synthesis in the skin, leading to skin lightening and brightening effects. 4-n-butylresorcinol has been shown to have greater hypopigmenting efficacy compared to established agents such as hydroquinone, arbutin, and kojic acid. It is approved in over-the-counter products for skin whitening, usually in cream or lotion formulations at concentrations up to 0.3%. Clinical studies support its efficacy and safety in hyperpigmentation, although higher concentrations or improper use may cause skin irritation.

Brand names

KopcinolRucinol

Other names

4-n-butyl resorcinol4-butylresorcin2,4-dihydroxy-n-butyl benzeneResorcinol, 4-butyl-4-(2,4-dihydroxyphenyl)butane