ABSTRACT
Objective: To optimize the formulation of paeonol lipid microspheres (Pae-LM) through central composite design- response surface method and determine its in vitro release characteristics. Methods: Using the mean particle size and centrifugal stability constant (Ke) as evaluation indexes, the oil phase type and the ratio of composite oil, the amount of phospholipid and stearic acid, the type of emulsifier, the type and amount of stabilizer, the quality of PC and CH, the high-speed shear temperature and time, the homogenization pressure and time was screened in prescription process. Effects of dosage of paeonol and high pressure homogenizing pressure on the properties of Pae-LM preparation were investigated by central composite design-response surface method. The binomial model and multivariate linear regression model were used to establish the mathematical relationship between the indexes and the factors. According to the best mathematical model of evaluation index, the response surface was depicted and the best prescription was analyzed by the response surface method. According to the optimized formulation Pae-LM, the in vitro drug release characteristics were investigated. Results: The best prescription of Pae-LM was basically round, with mean particle size of (149.32 ± 0.57) nm, Zeta potential of (-36.01 ± 3.09) mV, encapsulation rate of (98.24 ± 0.32)% and drug-loading rate of (11.94 ± 0.04)%. There was a credible quantitative relationship between Ke and the two factors, and the binomialmodel was more reliable than the multivariate linear model. The cumulative release of paeonol drug substance at 12, 24 and 36 h were 71.84%, 85.21% and 95.07%, while the cumulative release of Pae-LM was only 57.21%, 59.66%, and 63.91% at 12, 24 and 36 h, respectively. The drug release was in accordance with the Ritger-peppas model. Conclusion: Central composite design-response surface method can be applied to optimize prescription of lipid emulsion microspheres. The optimized particle size of Pae-LM was suitable with a higher encapsulation rate, which can provide a reference for the development of paeonol cardiovascular delivery system.
ABSTRACT
@#The formulations of pramipexole hydrochloride sustained-release tablets were screened by single factor test and optimized by Box-Behnken design. The effects of the viscosity and content of hydroxypropyl methyl cellulose, as well as the insoluble sustained-release material combined with HPMC K100M on the in vitro release behavior were investigated. After single factor screening, a three-factor, three-level Box-Behnken design was used for optimization using the contents of HPMC K100, Eudragit RSPO and Eudragit L100 as independent variables, and the cumulative release at different time as responses. The optimal range of the three-factor optimized by Box-Behnken design, one of the optimized formulations was achieved with HPMC K100M of 101. 5 mg, Eudragit RSPO of 98 mg, and Eudragit L100 of 13. 7 mg, and the observed responses of the optimized formulation were very close to the predicted values. The in vitro drug release mechanism of the tablet was studied by drug released model fitted with different equations. The results explained that Eudragit RSPO promoted the release of the pramipexole hydrochloride, while Eudragit L100 blocked the release, and there was an antagonism between them. In conclusion, the drug release behavior of optimized formulations prepared by Eudragit RSPO/L100 was stable, less pH-dependent, which improved the drug bioavailability in vivo.
ABSTRACT
Objective To study the formulation and preparation factors influencing in vitro release mechanism of drug from?-carrageenan/konjac glucomannan hydrophilic matrix tablets.Methods The matrix tablets containing sinomenine hydrochloride as a model drug were obtained by direct compression method or wet granulation technique.The effects of the ratios of?-carrageenan/konjac glucomannan,the amount of matrix materials,the kinds of diluent agent,tablet size,preparation method,and compressing pressure on release mechanism of the matrix tablets were studied by evaluating the n value in the Peppas equation. Results The release mechanism of the matrix tablets was non-Fickian release that coupled diffusion and erosion modle.With a decrease in the ratio of?-carrageenan/konjac glucomannan,a decrease in the amount of matrix materials,a decrease in the water-solubility of diluent agents,an increase in tablet size,and a decrease in compressing pressure,the ratio of drug diffusion was increased.Preparation method had little influence on drug release mechanism.Conclusion Drug could be slowly released from the matrix tablets containing?-carrageenan/konjac glucomannan as matrix material,the main factors influencing drug release mechanism are the ratio of?-carrageenan/konjac glucomannan,the amount of matrix materials, the kinds of diluent agent,tablet size,and compressing pressure.