Penetration Enhancing Effect of Polysorbate 20 and 80 on the In Vitro Percutaneous Absorption of LAscorbic Acid

Purpose: To investigate the penetration enhancing effect of two polysorbates - polyoxyethylene 20 (POE-20) and polyoxyethylene 80 (POE-80) - on the in vitro percutaneous absorption of ascorbic acid (AA). Methods: For the permeation experiments, Franz diffusion cell covered with aluminum foil providing an effective diffusion area of 1.76 cm^2 and hairless rabbit skin were used. A range of concentrations (1 – 5 %) of POE-20 and POE-80 was added to the ascorbic acid to determine their optimum enhancement concentration. Results: The cumulative amount of AA that diffused across the skin increased with increase in the concentration of the permeation enhancers. Without the enhancer, AA flux was 0.626 μg/cm^2/h while mean permeability coefficient (Kp) was 2.09 × 10^-6 cm/h. AA flux was 3.17 and 2.44 μg/cm^2/h for POE-20 and POE-80, respectively, while mean permeability coefficient was 10.6 × 10^-6 and 8.14 × 10^-6 Kp, cm/h. Maximum flux (3.16 μg/cm^2/h) at POE-20 concentration of 5 % was obtained, with an enhancement ratio (ER) of 5.07 in relation to control (i.e., AA without enhancer). For POE-80 (5 %), maximum flux was 2.44 μg/cm^2/h with an ER value of 3.89, compared to control. Conclusion: This study demonstrates that POE-20 and POE-80 exerted a penetration enhancing effect on the percutaneous absorption of L-ascorbic acid (AA).