Design and characterization of taste masked metronidazole microcapsules and its utilization in the formulation of orodispersible tablets

Abstract

Orodispersible tablet (ODT) containing microcapsules is an advanced and convenient drug delivery system that offers advantages of easy administration, and increased bioavailability. Metronidazole is an antiprotozoal, with a bitter and metallic taste as its major drawback. A taste masking is required since the tablet will disintegrate in the oral cavity releasing the drug into close proximity to the taste buds. The purpose of the study is to design and evaluate metronidazole microcapsules for formulation of taste masked orally ODT metronidazole tablets. Taste masked metronidazole microcapsules were prepared by emulsion polymerization method with sodium alginate as polymer using different drug to polymer ratio. The microcapsules were evaluated for drug loading, entrapment efficiency, drug-polymer interaction by FTIR spectrometry, DTA, and flow properties. Batches B4 and B5 were formulated into orally disintegrating tablet by direct compression method. The results of FTIR spectrometry and DTA characterization of microcapsules revealed absence of drug-polymer interaction. Evaluation of the microcapsules showed fairly good flow properties and increase in entrapment efficiency as the polymer concentration increased. Evaluation of the directly compressed ODTs showed acceptable weight variation, and average disintegration time less than 60 sec. The average tablet crushing strength range from 18 to 19 N, and the drug release profiles showed greater than 80% release of metronidazole within 10 min. The successful microencapsulation of metronidazole, fast disintegration, rapid drug release profile, and evidence of compatibility between metronidazole and the process polymer demonstrates the suitability of the microcapsules for formulation of orally disintegrating tablet for convenient delivery of metronidazole.Keywords: Orally disintegrating tablets, microencapsulation, taste masking