Formulation Optimization and Evaluation of Metronidazole Emulgel for Localized Management of Periodontal Infections

Abstract

Background: Periodontitis is a chronic inflammatory condition associated with periodontal pathogens, and conventional systemic antimicrobial therapy may be associated with systemic adverse effects and antimicrobial resistance. Localized delivery of antimicrobial agents directly into periodontal pockets may improve drug retention at the site of infection while reducing unnecessary systemic exposure. Metronidazole is particularly useful against anaerobic microorganisms associated with periodontal infections. The present study aimed to develop and evaluate a metronidazole-loaded mucoadhesive emulgel for localized periodontal drug delivery. Methods: Metronidazole emulgels were prepared using Carbopol 940 and Carbopol 934 as gelling agents. The formulation consisted of an oil-in-water emulsion incorporated into a gel base containing liquid paraffin, Span 20, Tween 20, propylene glycol, hydroxypropyl methylcellulose, and other suitable excipients. Six formulations (F1–F6) were prepared using different concentrations of Carbopol 940 or Carbopol 934. The prepared formulations were evaluated for physical appearance, homogeneity, pH, viscosity, spreadability, extrudability, drug content, and grittiness. Results: All formulations exhibited satisfactory physical characteristics and were free from phase separation and grittiness. The formulations showed variations in viscosity with changes in polymer concentration, with higher Carbopol concentrations producing greater viscosity. Spreadability was inversely related to viscosity. Drug content ranged from 95.0% to 97.2%, with F3 showing the highest value (97.2%) and F6 showing 97.0%. The evaluated formulations demonstrated acceptable extrusion characteristics, with F1, F3, and F6 reported as having excellent extrudability. Conclusion: The developed metronidazole emulgel formulations demonstrated satisfactory physicochemical properties and drug content, indicating their potential as localized periodontal drug delivery systems. Among the prepared formulations, F1, F3, and F6 were identified in the manuscript as promising formulations based on their overall physicochemical characteristics. However, further studies involving in-vitro drug release, mucoadhesive strength, periodontal retention, microbiological efficacy, comprehensive stability testing, and in-vivo evaluation are required before establishing therapeutic effectiveness.