Retinol Molecule

Retinoids are a common treatment option used to ameliorate acne, photodamage and PIH.

The mechanism of action likely involves the inhibition of tyrosinase, the dispersion of keratinocyte pigmented granules, reduction in pigment transfer and a reduction in corneocyte cohesion with an associated acceleration of epidermal turnover.

Tretinoin (all-trans retinoic acid) is a derivative of vitamin A that is thought to have an inhibitory effect on tyrosinase transcription.

Tretinoin is reported to be effective in treating melasma, with some associated side effects including erythema, peeling at the site of application and PIH .

Tretinoin is also used in combination in topical creams, such as a formulation proposed by Kligman and Willis containing 5% HQ, 0.1% tretinoin and 0.1% dexamethasone. Tretinoin in this formulation acts as a stimulant of epidermal turnover and pigment reduction via epidermopoieses, an antioxidant to reduce the oxidation of HQ and a mild irritant to enhance the epidermal penetration of HQ.