Preparation and evaluation of tamsulosin hydrochloride sustained-release pellets modified by two-layered membrane techniques

The aim of the present study was to develop tamsulosin hydrochloride sustained-release pellets using two-layered membrane techniques.Centrifugal granulator and fluidizedbed coater were employed to prepare drug-loaded pellets and to employ two-layered membrane coating respectively.The prepared pellets were evaluated for physicochemical characterization,subjected to differential scanning calorimetry(DSC)and in vitro release of different pH.Different release models and scanning electron microscopy(SEM)were utilized to analyze the release mechanism of Harnual■ and home-made pellets.By comparing the dissolution profiles,the ratio and coating weight gain of Eudragit■ NE30D and Eudragit■ L30D55 which constitute the inside membrane were identified as 18:1 and 10%-11%.The coating amount of outside membrane containing Eudragit■ L30D55 was determined to be 0.8%.The similarity factors(f_(2))of home-made capsule and commercially available product(Harnual■)were above 50 in different dissolution media.DSC studies confirmed that drug and excipients had good compatibility and SEM photographs showed the similarities and differences of coating surface between Harnual■ and self-made pellets before and after dissolution.According to Ritger-Peppas model,the two dosage form had different release mechanism.

Silicone matrices for controlled dexamethasone release:toward a better understanding of the underlying mass transport mechanisms

Dexamethasone-loaded silicone matrices offer an interesting potential as innovative drug delivery systems,e.g.for the treatment of inner ear diseases or for pacemakers.Generally,very long drug release periods are targeted:several years/decades.This renders the development and optimization of novel drug products cumbersome:experimental feedback on the impact of the device design is obtained very slowly.A better understanding of the underlying mass transport mechanisms can help facilitating research in this field.A variety of silicone films were prepared in this study,loaded with amorphous or crystalline dexamethasone.Different polymorphic drug forms were investigated,the film thickness was altered and the drug optionally partially/completely exchanged by much more water-soluble dexamethasone‘phosphate’.Drug release studies in artificial perilymph,scanning electron microscopy,optical microscopy,differential scanning calorimetry,X-ray diffraction and Raman imaging were used to elucidate the physical states of the drugs and polymer,and of the systems’structure as well as dynamic changes thereof upon exposure to the release medium.Dexamethasone particles were initially homogeneously distributed throughout the systems.The hydrophobicity of the matrix former very much limits the amounts of water penetrating into the system,resulting in only partial drug dissolution.The mobile drug molecules diffuse out into the surrounding environment,due to concentration gradients.Interestingly,Raman imaging revealed that even very thin silicone layers(<20µm)can effectively trap the drug for prolonged periods of time.The physical state of the drug(amorphous,crystalline)did not affect the resulting drug release kinetics to a noteworthy extent.

Are the release characteristics of Erzhi pills in line with traditional Chinese medicine theory?A quantitative study

Objective:Traditional Chinese medicine(TCM)has been widely used throughout China to prevent and cure diseases for thousands of years,and now it is a part of the integrative medicine field that is available in Western societies.To ensure the safety and quality of the herbal medicines that are a major part of the TCM tradition,they must be held to modern pharmaceutical standards.Erzhi pill(EZP)is a Chinese Pharmacopeia-listed herbal preparation that is used in the long-term clinical management of postmenopausal symptoms,osteoporosis and menstrual disorders.Until now,whether the drug release mechanism of EZP is in line with its intended TCM usage has not been studied.Methods:The release of specnuezhenide from three EZPs(self-made,Leiyunshang and Renhe)in simulated gastric fluid(SGF),acetate buffer(p H 4.5 buffer)and simulated intestinal fluid(SIF)was investigated in a dissolution test.The water uptake capacity and erosion extent of the three EZPs were investigated using swelling and erosion studies.The drug release mechanism was further assessed through statistical model fitting,using DDSolver software.Results:The release of specnuezhenide from all three EZPs in SGF was less than 50%within a 4 h period.However,over 70%of the specnuezhenide was released from each EZP in both p H 4.5 buffer and SIF in the same time.Analysis of the swelling and erosion behaviors and the drug release mechanism of the three EZPs confirmed that the release rate from EZP followed a sustained release profile,which was an interactive combination of swelling and erosion.Conclusion:This study showed that the release pattern from the pills was in line with the intended TCM use of EZP.TCM had not only theoretically considered sustained release from the pills,but also formulated them to achieve this release pattern.When establishing quality control standards for pills,the theoretical TCM usage and the actual release patterns need to be considered.