Development and in vitro evaluations of gelatin A microspheres of ketorolac tromethamine for intranasal administration

Gelatin A microspheres (MS) of ketorolac tromethamine (KT) for intranasal systemic delivery were developed with the aim to avoid gastro-intestinal complications, to improve patient compliance, to use as an alternative therapy to conventional dosage forms, to achieve controlled blood level profiles, and to obtain improved therapeutic efficacy in the treatment of postoperative pain and migraine. Gelatin A microspheres were prepared using the emulsification-crosslinking technique. The drug was dispersed in polymer gelatin and formulated into a w/o emulsion with liquid paraffin, using glutaraldehyde as a crosslinking agent. The formulation variables were drug loading and the concentrations of polymer (gelatin), co-polymer (chitosan) and the crosslinking agent. All the prepared microspheres were evaluated for physical characteristics, such as particle size, incorporation efficiency, swelling ability, in vitro bioadhesion on rabbit small intestine and in vitro drug release characteristics in pH 6.6 phosphate buffer. All the microspheres showed good bioadhesive properties. Gelatin A and chitosan concentrations, percentage of the crosslinking agent and also the drug loading affected significantly the rate and extent of drug release. The data indicated that the KT release followed Higuchi's matrix model.