RESUMO
Purpose: The aim of the present investigation was to formulate protein nanoparticles (PNPs) loaded suppositories for colon targeting of metronidazole (MZ), to achieve sustain release effect. Methods: PNPs were formulated via desolvation technique by utilizing 23 factorial design which results into eight formulations. The synthesized PNPs were characterized for different physicochemical and in vitro parameters viz. particle size, surface morphology, entrapment efficiency and zeta potential, drug- excipients compatibility studies. Results: The formulated PNPs were found to be spherical in shape and have an average size in the range of 300.7 nm to 504.8 nm. Based on the results obtained, F7 was found to be the optimized formulation that was loaded into the suppository base. Furthermore, suppositories were also characterized for several parameters like content uniformity, weight variation and liquefaction time. Conclusion: Resultant, suppositories were free from pits, fissures and cracks. The in-vitro release data of MZ-PNPs loaded suppositories were compared with the suppositories loaded with active ingredient only i.e. MZ. Screening against Pheretima posthuma was also conducted. The results of in vitro drug release testing proved that protein nanoparticle loaded suppositories is a better approach, compared to pure MZ loaded suppositories. Release kinetic study concluded that the formulation follows Higuchi's equation i.e. having a biphasic release pattern. The efficiency of the formulated dosage form was evaluated using Indian earthworms, P. posthuma.
