The objective of this study was to develop and evaluate mucoadhesive microsphere of diclofenac sodium with
natural gums for sustained delivery. Guar gum and tragacanth were used along with sodium alginate as mucoadhesive
polymers. Microspheres were formulated using orifice-ionic gelation method. Particle size, surface morphology, swelling
study and drug entrapment efficiency of the prepared microspheres were determined. In vitro evaluation was carried out
comprising of mucoadhesion and drug release study. The prepared microspheres were discrete and free flowing. Sodium
alginate and natural gum, at a ratio of 1:0.25, showed good mucoadhesive property and they had high drug entrapment efficiencies.
They also exhibited the best rate retarding effect among all the formulations. Drug entrapment efficiency of all
the microspheres ranged from 80.42% to 91.67%. An inverse relationship was found between extent of crosslinking and
drug release rate. Release rate was slow and extended in case of the formulations of 1:0.25 ratio (F1 and F3), releasing
68.36% and 70.56% drug respectively after 8 hours. Tragacanth-containing microspheres of F1 showed superiority over
other formulations, with best mucoadhesive and rate retarding profile. The correlation value (r2) indicated that the drug release
of all the formulations followed Higuchi’s model. Overall, the results indicated that mucoadhesive microspheres
containing natural gum can be promising in terms of prolonged delivery with good mucoadhesive action, targeting the absorption
site to thrive oral drug delivery.
Keywords: Crosslinked microsphere, diclofenac sodium, sustained delivery, mucoadhesive microsphere, natural gum, orificeionic
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