Formulation and Evaluation of Mucoadhesive Microspheres of Metronidazole Using the Orifice Ionic Gelation Method

The present study investigated the formulation and evaluation of mucoadhesive microspheres of metronidazole using the orifice ionic gelation (ionotropic gelation) technique. Sodium alginate was used as the principal matrix-forming polymer and was combined, where applicable, with hydroxypropyl methylcellulose (HPMC K100M), ethyl cellulose, or methyl cellulose as secondary polymers. Calcium chloride (10% w/v) was used as the curing medium. Eight formulations (F1–F8) were prepared by varying the polymer type and polymer-to-drug ratio. The microspheres were evaluated for micromeritic properties, drug content/encapsulation efficiency, in-vitro dissolution, mucoadhesion by the wash-off method in pH 1.2 HCl and pH 7.0 phosphate buffer, FTIR compatibility, and SEM morphology. The supplied dataset identified F7 (metronidazole:sodium alginate:methyl cellulose, 1:2:1) as the optimized formulation. F7 showed an encapsulation efficiency of 77.51 ± 0.025%, prolonged drug release to 97.11 ± 2.98% at 8 h, and the highest sustained mucoadhesion among the tested batches, with 39% remaining at 5 h and 26% at 6 h in pH 7.0 phosphate buffer. FTIR observations indicated no major drug–polymer incompatibility, while SEM showed spherical, polymer-coated particles with visible pores. Overall, the supplied results support F7 as a promising formulation for further development of an oral controlled-release mucoadhesive microsphere system. Because the source document contains some reporting inconsistencies, the manuscript preserves the reported values and flags these issues rather than introducing unsupported corrections.