Caffeine microspheres - an attractive carrier for optimum skin penetration

Abstract

IFSCC Magazine, 12 (4) 359–363 (2009) Synopsis Caffeine is an effective slimming agent used for topical administration or in cosmetic products. The formulation must be such that caffeine reaches the adipocytes in the hypodermis. Biodegradable caffeine-loaded microspheres were evaluated for the transport of caffeine to its site of action for 24 h and upto 72 h. The mean diameter of the microspheres was 2.8 μm and their caffeine loading was 2.3 mg g-1 of particles. The permeation of caffeine from microspheres applied in aqueous suspension or from solution was evaluated through in vitro diffusion measurements with static Franz cells (n = 6) over 24 h or 72 h. The first experiments carried out on full-thickness skin without hypodermis showed that after 24 h the total amount of caffeine was twice as high from microspheres as from aqueous solution (22.6% vs. 9.99%). The results suggested that microspheres could easily penetrate through the skin and accumulate in the receptor compartment, ensuring continuous caffeine release. When the hypodermis was retained, microsphere penetration was only slightly decreased. After 72 hours of exposure the receptor fluid contained 15.3% free caffeine and 27.8% encapsulated fraction. The hypodermis hindered solution permeation, and therefore the free caffeine content was lower. Permeation of microspheres was not stopped by the presence of hypodermis.