Natural mucoadhesive microspheres of Abelmoschus esculentus polysaccharide as a new carrier for nasal drug delivery.

This work describes the preparation and evaluation of mucoadhesive microspheres, using Abelmoschus esculentus polysaccharide as a novel carrier for safe and effective delivery of rizatriptan benzoate into nasal cavity. The polysaccharide was extracted from the fruit of A. esculentus and mucoadhesive microspheres were prepared by emulsification, followed by crosslinking using epichlorohydrin. Prepared microspheres were evaluated for size, morphology, swelling properties, mucoadhesive strength, encapsulation efficiency and drug release. Microspheres were found to release 50% of drug within 15 min and rest of the drug was released within 60 min. The drug release was found to decrease with increasing concentration of polysaccharide. To determine the retention time of the microspheres in the nasal cavity of rabbits, the microspheres were radiolabelled with (99m)Tc and subjected to gamma scintigraphy. The results showed a significant improvement in the nasal retention of the microspheres as compared to the aqueous solution of radiolabelled free-drug.