EVALUATION OF LIQUID CRYSTAL FORMULATION FOR PHOTODYNAMIC THERAPY: STABILITY AND TESTS

TF11

Raquel Petrilli, Aline Regina Hellmann Carollo, Fábia Cristina Rossetti, Kleber Thiago de Oliveira, Yassuko Iamamoto and Maria Vitória Lopes Badra Bentley.

Faculdade de Ciências Farmacêuticas de Ribeirão Preto (FCFRP) and Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP)

Photodynamic Therapy (PDT) is a medical treatment which employs the combination of light and a drug (photosensitizer) to bring about a cytotoxic or modifying effect to cancerous or otherwise unwanted tissue. It is a great promise thanks to its dual-selective mode of action. Firstly, a photosensitizer of negligible dark toxicity is introduced into the body and accumulates preferentially in rapidly dividing cells. When the drug reaches an appropriate ratio of accumulation in diseased versus healthy tissue, a carefully regulated light dose is shone onto the diseased tissue. Light activates the drug and elicits the toxic action. The amount of light needs to be large enough to cause the desired response in the tissue, but small enough to spare the surrounding (and incidentally illuminated) healthy tissue from extensive damage. Shortly after treatment, the damaged cells become necrotic, or suitably modified. The aim of this work was the pharmaceutical development of liquid crystal formulations containing monoolein, oleic acid and water, seeking the increase of the cutaneous penetration of the chlorin in the skin, for skin cancer PDT. Studies of formulation for application in PDT with desirable characteristics of permeation and retention on skin were carried out through ternary diagrams monoolein/oleic acid/water, on different temperatures and times. One formulation was then chosen and turbidimetry of the sample was monitored through 72 hours. Permeation and retention in vitro tests were also conducted for the formulation associated with a chlorin, using fluorescence intensity to quantify the chlorin. It was observed through ternary diagrams that most of the formulations tested showed up to be stable over time tracked (2 weeks). Was then chosen a formulation of hexagonal phase, which also showed good stability through turbidimetry during monitored time (72 hours). Permeation and retention in vitro tests showed that the drug remained trapped in the stratum corneum (SC) and [epidermis + dermis] and was not detected in the permeation solution. The formulation tested presented good characteristics for application on photodynamic therapy, using the chlorin as photosensitizer.