INTRODUCTION
As people age, they become increasingly concerned with their skin appearance, especially on photoexposed
areas. The changes that derive from chronic sun exposure superimposed on intrinsically aged skin are collectively
known as photoaging. Clinically, this presents with leathery
and yellowish appearance, irregular pigmentation, coarse wrinkles (or severe atrophy depending on the person), lack of skin elasticity, and often neoplasia, which at times may be malignant.
1,2 Histologically, photoaging shows keratinocyte atypia, variability in epidermal thickness and melanocyte distribution, loss of epidermal polarity, loss and alteration of dermal matrix, and, especially, degeneration of elastic fibers (elastosis).2-4
Many topical agents are currently marketed for the improvement of phodamaged skin. Among these, tretinoin (all-trans-retinoic acid) is considered the gold standard and numerous clinical trials
have independently confirmed its ability to partially reverse photoaged skin at the clinical, histological, and molecular level. (Leyden 1989, Singh 2006).5,6 The main drawback of tretinoin, however, is the frequency of skin irritation. Additionally, it is available only by prescription, and thus accessible only to a limited
population. This has led the industry to research alternatives in the area of active cosmetics (cosmeceuticals) for photoaging.
A precursor of tretinoin, retinol has great potentials as an anti-aging molecule and a long history of use as an antioxidant in cosmetic formulations. Applied to skin, retinol has been shown to penetrate the barrier7 and to induce clinical and histological changes without signs of irritation.8 However, only a handful of clinical studies have been published in peer-reviewed journals on the benefits of retinol in aging9 and photoaging.10 One reason could be that retinol is very unstable; thus, retaining the bioactivity
of retinol in commercial products is challenging. Recently, a vehicle-controlled study by Tucker-Samaras et al. found that a formulation of 0.1% stabilized retinol was able to significantly improve facial photodamage after just 8 weeks of use.10
The aim of the current study was to assess the efficacy and safety
of 0.1% stabilized retinol in photoaging for longer periods of use (52 weeks) and to document histological and histochemical changes after treatment for 52 weeks.
METHODS
Two 52-week, double-blind, vehicle-controlled studies were designed
to evaluate the efficacy and safety of a topical retinol formulation in photoaging. One study (Clinical Study) evaluated
clinical improvements after application of either a retinol
