Preparation, rheological study, and characterization of an organogel as a system for transdermal release of active principles.

The use of formulations containing Pluronic gel as a vehicle and permeabilizing agent for transdermal preparations has increased in recent years. We prepared and compared two transdermal formulations for drug administration as an alternative to oral or parenteral administration. In formulations containing Pluronic F127 gel or pluronic lecithin organogel (PLO), rheological, structural (transmission electron microscopy) and physicochemical characteristics were studied under different conditions of composition, temperature, and time from 24 hr to 3 months after preparation. Rheological studies at 20-25 degrees C and at 4 degrees C to study the influence of refrigeration on viscosity and pH showed that both formulas were thermoreversible. Unilamellar vesicles smaller than 1 microm in diameter were seen in the PLO formulation on TEM observation. The characteristics of these excipients may facilitate the application and may avoid the gastrointestinal tract and the first-pass effect.