A Quality by Design Approach of Metronidazole Bigel and Assessment of Antimicrobial Study Utilizing Box-behnken...

The present investigation aimed to prepare metronidazole (MTZ) topical bigel for the effective delivery of MTZ and to study the effect of applied variables as per statistical design. The study also signifies the implementation of the statistical method using the Quality by Design technique for MTZ bigel.

The MTZ bigels were prepared as per the runs suggested by Box Behnken design (BBD) using statistical software. A total of 28 runs were suggested by the BBD, considering sodium carboxymethylcellulose (Na CMC), guar gum, hydrogel and RPM as independent variables. The prepared bigels were evaluated for organoleptic properties, percentage drug content, spreadability, viscosity, percentage in-vitro drug release, and antimicrobial efficacy. Model selectivity was ascertained by p-value considering responses along with predicted R² and adjusted R² values.The fitting of model was ascertained by F-value as well as "lack of fit" was carried out to find out the suitability of the experimental design. Furthermore, the characteristic distribution of data was ascertained by the "normal plot of residual" method. The compatibility of MTZ and excipients in bigels was confirmed by FTIR and the crystalline nature of MTZ in formulations was studied by DSC and XRD studies. Furthermore, the dispersion of bigel was assessed by the SEM study.

The effect of independent variables on spreadability (mm), viscosity (cp), pH, drug release in 6 hours (%)and drug content (%) was evaluated. The optimized formulation was selected and evaluated by a polynomial equation while considering the p-value. These variables showed a significant effect on responses. A less significant difference was observed (6.37, 14463, 6.97, 86.29, and 67.47, respectively, for spreadability, viscosity, pH, and percentage drug release and % drug content) between the observed and predicted values indicating the model's suitability. The prepared bigels were found to be compatible and globules uniformly dispersed throughout the bigel.

The 3D response surface design ascertained the optimal MTZ bigel at 1.25g of NaCMC, 0.5g of guargum, 37.5g hydrogel, and 1000 RPM. The selected bigel showed good antimicrobial efficacy against S. Aureus and may be considered an effective delivery vehicle for MTZ.