Study On Release Mechanism Of Chuanping Sustained-release Preparation With Modified Excipients 1

Objective Clarify the drug release mechanism of Chuanping sustained-release tablets with modified excipients 1 as a framework material.Method To study the releasing rate of Chuanping sustained-release tablets with modified excipients 1 as a framework material,and on this basis,the releasing rate is fitted with zero order model,level model,Higuchi equation,and Peppas equation.Measure the erosion,the thickness of the gel layer and the wetting layer of the sample dissolution of the tablet from the dissolution process each specified time point, and combined with morphological changes,the falling particle size,dynamic changes and gel strength to study the release mechanism of Chuanping sustained-release tablets with modified excipients 1 as a framework material,at the same time, compared with Chuanping sustained-release tablets with hydroxypropyl methylcellulose as a framework material.Results ①The releasing rate from Chuanping sustained-release tablets with modified excipients 1 and hydroxypropyl methylcellulose as framework material were analyzed kinetically using Peppas equation.The n values of the main indicators including ephedrine hydrochloride, pseudoephedrine hydrochloride and scopolamine hydrobromide in all three kinds of sustained-release tablets ranged in between 0.45 and 0.89,indicating that drugs were released based on diffusion and dissolution.Shedding particles still contained a small amount of the drug,and the drug was not fully released in the process of dissolution. ②The corrosion degree of three kinds of different sustained-release tablets were increased within the increasing time and the increase of the accumulative release rate, indicating that the cumulativerelease rate and degree of corrosion were positively related. ③ Three zones(gel layer,infiltrated region and glassy core)could be easily observed in the sustained-release tablets through using a stered microscope. As time increased, the thickness of the gel layer and infiltrated region slowly became thicker,after a certain time,the thickness of the gel layer changed little,and tended to be constant. ④The size of falling particles differed from one prescription to another with largest particles from prescription 1 and relatively smaller ones from prescription 2. ⑤ As the drug dissolved, fallen particles accumulated on the bottom of the cup during a period time.The structure of prescription 1 had begun to fall apart in about 6 h,and more falling particles could be observed compared to other two prescriptions. The prescription 2 and 3 still hold structure intact in 8 h. ⑥ The gel strength of the prescription 1 decreased slowly with the increase of time, and the gel strength of 6 h was slightly smaller than that of 4 h, but the differences were not apparent.Conclusion The release mechanism of the sustained-release tablets is driven by both diffusion and erosion processes. In addition, the prescription 1 was found that many particles dropped off from the surface of the tablet, indicating a possible new erossion-dissolving-diffusion mode for the sustained-release tablet. And the prescription 2 and the prescription 3 in the dissolution process also were found that particles from the surface of the tablet fell down but relatively few, therefore, it may exist dissolution,but diffusion and erosion may still be predominant.