Topical liquid crystalline gel containing lornoxicam/cyclodextrin complex

Lornoxicam is a potent analgesic non-steroidal anti-inflammatory drug that can be used topically to relieve pain and to reduce inflammation. The objectives of this study were to improve the therapeutic efficacy of lornoxicam by complexation with cyclodextrins and to formulate it in liquid crystalline gel. Lornoxicam and beta-cyclodextrin (beta CD) or hydroxypropyl-beta-cyclodextrin (HP beta CD) complexes were prepared using the kneaded method in 1:1, 1:2, 1:3 and 1:4 drug:CD molar ratios. Inclusion complexation in aqueous solution and solid state was evaluated by the ultraviolet, phase solubility diagram, differential scanning calorimetry, X-ray diffractometry and Fourier-transform infrared spectroscopy. The stoichiometry for the inclusion complex was found to be 1:2 drug:CD molar ratio as determined from Job's plot. This result was confirmed by the in vitro dissolution studies for the prepared complexes. Among all the prepared complexes, the complex prepared with beta CD in 1:2 drug:CD molar ratio showed highest improvement in drug dissolution and was chosen to be formulated in a topical preparation. For developing liquid crystalline gel, different ratios of Brij 97, glycerol and oils (liquid paraffin, isopropyl myristate and Miglyol(A (R)) 812) were prepared. The formula composed of Brij 97 and glycerol in 3:1 weight ratio, 10% Miglyol(A (R)) 812 and 40% water showed higher drug release compared to the other prepared gels. Moreover, this formula showed low ex vivo permeation on excised pigskin thus it could offer high topical effect with low systematic side effects. This formula showed superior anti-inflammatory activity when applied topically on rats' skin after induction of burn compared to that of Feldene(A (R)) gel.