Formulation and In Vitro Evaluation of pH-Sensitive Oil-Entrapped Buoyant Beads of Clarithromycin

Purpose: To develop pH-sensitive controlled release formulation of clarithromycin in oil-entrapped calcium pectinate microgel bead.
Methods: Pectin-based oil-entrapped microgel beads were prepared by ionic gelation technique. The gel beads were formed instantly after adding the liquid formulation mixture dropwise into calcium chloride solution. The beads were optimized by coating with ethylcellulose solution and then evaluated for their diameter, floating lag time, encapsulation efficiency and drug release.
Results: Particle size, encapsulation efficiency and buoyancy were significantly affected by the concentration of the polymer and calcium chloride .The formulation exhibited sustained release profile and was best fitted to the Peppas model with n < 0.45. Ethylcellulose-coated formulation batch, C₁₆, was the most suitable controlled formulation with drug release of 65 ± 2.61 % in 8 h.
Conclusion: An ethylcellulose-coated formulation with potential for sustained delivery of clarithromycin in the acidic region of the gastrointestinal tract was successfully developed.

Keywords
Clarithromycin; Calcium pectinate bead; Gastric residence time; pH-sensitive; Ethyl cellulose; Oil-entrapped