Characterization of new topical ketoprofen formulations prepared by drug entrapment in solid lipid matrices

This paper describes the evaluation of a new pharmaceutical formulation based on ketoprofen entrapment in a solid lipid particle (SLP) matrix. The drug-SLP samples, which were elaborated using a processing technology based on supercritical CO2, consisted of a model of a controlled‐release system for topical applications. Some of the samples contained silanized TiO2 as an additional ingredient to increase the interaction between drug and lipid matrix. The study of the sample features relied on reversed‐phase high‐performance liquid chromatography with a C18 column and ultraviolet spectroscopic detection at 266 nm. Characterization assays comprised the determination of the overall amount of ketoprofen in the samples, the assessment of the release-permeation kinetic profiles, and the evaluation of impurities and decomposition products. The release and permeation of encapsulated ketoprofen were assayed at 32°C and pH 6.8 by using a static diffusion cell. Results showed a sustained drug delivery for at least 24 h. Besides, no degradation species were detected throughout the release-permeation processes, which indicated that the stability of the drug in the SLP system was preserved. © 2011 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 100:4783-4789, 2011