Preparation and Drug Release Mechanism of Tetramethylpyrazine Phosphate Porosity Osmotic Tablet / 中国药房

ABSTRACT

OBJECTIVE:To prepare Tetramethylpyrazine phosphate porosity osmotic tablet (TMPP) and to optimize its formulation and investigate its mechanism of drug release. METHODS: The formulation was optimized by the orthogonal experiment design through investigation of one factor; the accumulative drug release rates of preparations of different formulation were measured, and the mechanism of drug release of the tablets was discussed. RESULTS: The dosage of PEG 400 in coating solution, the content of hydroxy-propyl methyl cellulose (HPMC) in tablet core, the dosage of dibutylphthalate as plasticizer, and the weight gain of coating membrane were four important factors influencing drug release. The optimal formulation was to use 10% of PEG400, 5% of HPMC, 10% of dibutylphthalate and 12 mg coating membrane. The release behavior in vitro of the porosity osmotic tablets prepared in the above condition within 10 h complied with zero order release rule(r=0.999 81), with accumulative release rate of 94.2%. The tablets had good reproducibility in interassay and which was independent of the influence of gastrointestinal condition. The mechanism of drug release included osmotic pump mechanism and diffusion mechanism, but osmotic pump one was the main type. CONCLUSION: The formulation and preparation technology of the porosity osmotic tablets were simple but effective, showing an obvious zero order release within 12 h and good reproducibility, thus suitable for the industrial production of porosity osmotic tablets.