Introduction :
Photoprotection is the main way of preventing damage caused by solar radiation, ie, erythema, aging, and skin cancer. Nonmelanoma skin cancer is the most common tumor type in Brazil.1 Currently, 2–3 million nonmelanoma skin cancers and 132,000 melanoma skin cancers occur globally each year. One in every three cancers diagnosed worldwide is a skin cancer, according to Skin Cancer Foundation statistics.2 Antisolar preparations contain sunscreens that absorb, reflect, or scatter ultraviolet radiation from sunlight. For more photostable formulations, with a high sun protection factor (SPF) and providing broad spectrum ultraviolet radiation protection, three or more sunscreen agents are used. These agents are generally lipophilic substances applied on a large area of the body. Therefore, systemic absorption is a factor to be considered.
The anti-ultraviolet B organic filter, octyl p-methoxycinnamate (OMC), first developed in the 1950s, has been one of the most widely used sunscreens, and its use in pharmaceutical and cosmetic formulations is allowed by, among other entities, the US Food and Drug Administration, the European Cosmetics, Toiletry, and Perfumery Association (COLIPA) and the Brazilian Agência Nacional de Vigilância Sanitária. Several studies have shown that OMC present in conventional formulations can be systemically absorbed after skin application, being found in the deeper layers of the stratum corneum as well as urine, plasma, and breast milk.
The development of sunscreen formulations containing nanoparticulate systems is of great interest in the pharmaceutical and cosmetic industries because of the many potential benefits, such as tailoring the release profile, improving SPF and stability, and reducing side effects.12–14 The crucial factor in assessing skin preparations containing nanostructures is the risk of permeation through transdermal, mucosal, or follicular pathways. Thus, it is necessary to know more about the cutaneous permeation, enzymatic metabolism, and biodistribution of these nanostructured systems in order to evaluate their safety
Liposomes can be defined as the result of colloidal association of phospholipids, which are spontaneously organized in closed spherical vesicles consisting of one or more phospholipid bilayers that completely surround an aqueous inner compartment. Liposome vesicles enable the incorporation of both hydrophilic and lipophilic compounds.
The aim of this work was to develop and evaluate a liposome/OMC nanosystem and a gel formulation containing it in order to obtain a sunscreen formulation with improved safety and efficacy by keeping the OMC on the stratum corneum for a longer period of time.