Skin Lightening Agents

Introduction

Hyperpigmentation is a common skin problem that is particularly prevalent in middle-aged and elderly individuals. It is cosmetically important and can greatly detract from both appearance and quality of life, particularly in cultures where smooth skin is valued as a sign of health or in cultures that are beauty conscious. Hyperpigmented skin lesions may be postinflammatory as a sequel to acne, trauma, chemical peels, or laser therapy. Exogenous causes, particularly ultraviolet (UV) light exposure, are a common factor in pigmentary abnormalities such as melasma, solar lentigines, and ephelides ( Fig. 12.1 ). Exposure to certain drugs and chemicals as well as the existence of certain disease states can result in hyperpigmentation ( Box 12.1 ).

The treatment of acquired hyperpigmentation has traditionally been challenging and frequently discouraging. Many of the agents that have been used cause skin irritation, require many months of regular use before results are apparent, or are only partly effective. Patient compliance with therapy must be strict. Sun avoidance and the religious use of a high sun protection factor (SPF) sunblock are mandatory for successful treatment.

Skin lightening cosmeceuticals

Multiple depigmenting cosmeceuticals are currently available, although published clinical evidence to support their effectiveness is lacking. These skin lightening compounds work by removing undesired pigment by acting at one or more steps in the pigmentation process ( Box 12.2 ). Since tyrosinase is the rate-limiting enzyme for melanin biosynthesis, many of the cosmeceuticals for skin lightening exert their effect on this enzyme.