Preparation and characterization of spray-dried mucoadhesive microspheres of ketorolac for nasal administration

The objective of this investigation was to prepare mucoadhesive microspheres of ketorolac for nasal delivery to avoid gastrointestinal side effects of conventional dosage form. Mucoadhesive microspheres were prepared using carbopol, polycarbophil and chitosan as polymer by spray drying method. The process and formulation parameters were varied to study the effect on the yield and particle size. Microspheres were characterized for surface morphology, encapsulation efficiency, swelling behavior, mucoahesion properties, interaction studies using FTIR and DSC, in vitro drug release, ex vivo nasal cilio toxicity studies and in vivo anti-inflammatory and analgesic activity. Prepared microspheres were discrete, bulky, free flowing and showed an average encapsulation efficiency ranging from 79-92%. The results showed that the process parameters significantly affect the particle size (10.29-16.75 μm) and yield of microspheres (36.53-56.69%). Interaction studies revealed that there were no drug to polymer interactions. Prepared microspheres exhibited good swelling and mucoadhesion strength which confined the strong mucoadhesive property of microspheres. Ketorolac release from the microspheres was extended up to 8 h and exhibited fickian drug release kinetics with best fit to higuchi model. The drug loaded microspheres were found to be nontoxic to nasal mucosa. The anti-inflammatory and analgesic effects of formulation showed a significant increase (p < 0.05) in percent inhibition value of up to 8 h when compared with ketorolac. In conclusion, spray dried microspheres based on chitosan could be suitable nasal delivery system for the administration of ketorolac.