ABSTRACT
Defining and visualizing the three-dimensional (3D) structures of pharmaceuticals provides a new and important tool to elucidate the phenomenal behavior and underlying mechanisms of drug delivery systems. The mechanism of drug release from complex structured dosage forms, such as bilayer osmotic pump tablets, has not been investigated widely for most solid 3D structures. In this study, bilayer osmotic pump tablets undergoing dissolution, as well as after dissolution in a desiccated solid state were examined, and visualized by synchrotron radiation micro-computed tomography (SR-μCT). In situ formed 3D structures at different in vitro drug release states were characterized comprehensively. A distinct movement pattern of NaCl crystals from the push layer to the drug layer was observed, beneath the semi-permeable coating in the desiccated tablet samples. The 3D structures at different dissolution time revealed that the pushing upsurge in the bilayer osmotic pump tablet was directed via peripheral "roadways". Typically, different regions of the osmotic front, infiltration region, and dormant region were classified in the push layer during the dissolution of drug from tablet samples. According to the observed 3D microstructures, a "subterranean river model" for the drug release mechanism has been defined to explain the drug release mechanism.
ABSTRACT
Changes in structure of oral solid dosage forms (OSDF) elementally determine the drug release and its therapeutic effects. In this research, synchrotron radiation X-ray micro-computed tomography was utilized to visualize the 3D structure of enteric coated pellets recovered from the gastrointestinal tract of rats. The structures of pellets in solid state and in vitro compendium media were measured. Pellets in vivo underwent morphological and structural changes which differed significantly from those in vitro compendium media. Thus, optimizations of the dissolution media were performed to mimic the appropriate in vivo conditions by introducing pepsin and glass microspheres in media. The sphericity, pellet volume, pore volume and porosity of the in vivo esomeprazole magnesium pellets in stomach for 2 h were recorded 0.47, 1.55 × 108 μm3, 0.44 × 108 μm3 and 27.6%, respectively. After adding pepsin and glass microspheres, the above parameters in vitro reached to 0.44, 1.64 × 108 μm3, 0.38 × 108 μm3 and 23.0%, respectively. Omeprazole magnesium pellets behaved similarly. The structural features of pellets between in vitro media and in vivo condition were bridged successfully in terms of 3D structures to ensure better design, characterization and quality control of advanced OSDF.
ABSTRACT
Effective methods for visualizing neurovascular morphology are essential for understanding the normal spinal cord and the morphological alterations associated with diseases. However, ideal techniques for simultaneously imaging neurovascular structure in a broad region of a specimen are still lacking. In this study, we combined Golgi staining with angiography and synchrotron radiation micro-computed tomography (SRμCT) to visualize the 3D neurovascular network in the mouse spinal cord. Using our method, the 3D neurons, nerve fibers, and vasculature in a broad region could be visualized in the same image at cellular resolution without destructive sectioning. Besides, we found that the 3D morphology of neurons, nerve fiber tracts, and vasculature visualized by SRμCT were highly consistent with that visualized using the histological method. Moreover, the 3D neurovascular structure could be quantitatively evaluated by the combined methodology. The method shown here will be useful in fundamental neuroscience studies.
ABSTRACT
Effective methods for visualizing neurovascular morphology are essential for understanding the normal spinal cord and the morphological alterations associated with diseases. However, ideal techniques for simultaneously imaging neurovascular structure in a broad region of a specimen are still lacking. In this study, we combined Golgi staining with angiography and synchrotron radiation micro-computed tomography (SRμCT) to visualize the 3D neurovascular network in the mouse spinal cord. Using our method, the 3D neurons, nerve fibers, and vasculature in a broad region could be visualized in the same image at cellular resolution without destructive sectioning. Besides, we found that the 3D morphology of neurons, nerve fiber tracts, and vasculature visualized by SRμCT were highly consistent with that visualized using the histological method. Moreover, the 3D neurovascular structure could be quantitatively evaluated by the combined methodology. The method shown here will be useful in fundamental neuroscience studies.
Subject(s)
Animals , Mice , Imaging, Three-Dimensional , Neural Networks, Computer , Spinal Cord/diagnostic imaging , Synchrotrons , X-Ray MicrotomographyABSTRACT
The shape and structure of granules are controlled by the granulation process, which is one of the main factors to determine the nature of the solid dosage forms. In this article, three kinds of granules of a traditional Chinese medicine for improving appetite and promoting digestion, namely, Jianwei Granules, were prepared using granulation technologies as pendular granulation, high speed stirring granulation, and fluidized bed granulation and the powder properties of them were investigated. Meanwhile, synchrotron radiation X-ray computed micro tomography (SR-µCT) was applied to quantitatively determine the irregular internal structures of the granules. The three-dimensional (3D) structure models were obtained by 3D reconstruction, which were more accurately to characterize the three-dimensional structures of the particles through the quantitative data. The models were also used to quantitatively compare the structural differences of granules prepared by different granulation processes with the same formula, so as to characterize how the production process plays a role in the pharmaceutical behaviors of the granules. To focus on the irregularity of the particle structure, the box counting method was used to calculate the fractal dimensions of the granules. The results showed that the fractal dimension is more sensitive to reflect the minor differences in the structure features than the conventional parameters, and capable to specifically distinct granules in structure. It is proved that the fractal dimension could quantitatively characterize the structural information of irregular granules. It is the first time suggested by our research that the fractal dimension difference (Df,c) between two fractal dimension parameters, namely, the volume matrix fractal dimension and the surface matrix fractal dimension, is a new index to characterize granules with irregular structures and evaluate the effects of production processes on the structures of granules as a new indicator for the granulating process control and optimization.
ABSTRACT
The present study establishes a visualization method for the measurement of the distribution and localization of protein/peptide constituents within a single poly-lactide-co-glycolide (PLGA) microsphere using synchrotron radiation-based Fourier-transform infrared spectromicroscopy (SR-FTIR). The representative infrared wavenumbers specific for protein/peptide (Exenatide) and excipient (PLGA) were identified and chemical maps at the single microsphere level were generated by measuring and plotting the intensity of these specific bands. For quantitative analysis of the distribution within microspheres, Matlab software was used to transform the map file into a 3D matrix and the matrix values specific for the drug and excipient were extracted. Comparison of the normalized SR-FTIR maps of PLGA and Exenatide indicated that PLGA was uniformly distributed, while Exenatide was relatively non-uniformly distributed in the microspheres. In conclusion, SR-FTIR is a rapid, nondestructive and sensitive detection technology to provide the distribution of chemical constituents and functional groups in microparticles and microspheres.
ABSTRACT
The release behavior of single pellet was investigated by LC/MS/MS method with tamsulosin hydrochloride (TSH) as the model drug of the research and then the pellets were divided into four groups according to the drug loading. Comparison of dissolution profiles of each group and capsule were performed using f1 and f2 factor methods to study the difference and similarity. The release profiles of single pellet, each group and capsule were analyzed using principle component analysis (PCA). The particle system was built through Matlab to get the target release profile. The result of this research demonstrated the release behavior of single pellet correlated well with the drug loading. While the dissolution profile of capsule as a reference, the similarity factor of dissolution profiles of the lower drug loading groups were 62.2, 67.1, 53.9, respectively and, 43.3 for highest drug loading group. The particle systems with different pellet distribution and same release profiles were built through release behavior of single pellet. It is of significance to investigate the release behavior of single pellets for studying the release regularity of multiple-unit drug delivery system.
ABSTRACT
The crystal form of solid substance had intrinsic correlation with its three dimensional crystal morphology. Based on the characterization of the three dimensional crystal morphology of clopidogrel bisulfate, this research is to establish a model based on the three dimensional morphological parameters. The granular samples composed of polymorphs of clopidogrel bisulfate and microcrystalline cellulose (MCC) were scanned by synchrotron radiation X-ray microscopic CT technology (SR-microCT) and the three dimensional structural models for which were constructed. Seven groups of three dimensional morphological parameters were calculated. Finally, the mathematical model was established with the multi-layer perception (MLP) artificial neutral network methods to identify and predict the polymorphs of clopidogrel bisulfate. The success rate of the model prediction for the polymorphs of clopidogrel bisulfate was 92.7% and the area under the ROC curve was 96.2%. The polymorphs of drugs could be identified and predicted through the numerical description of the three dimensional morphology. The volume, number of the vertices and the surface area were the major determinants for the identification of the polymorphs of clopidogrel bisulfate.
ABSTRACT
The purpose of this study is to investigate the applicability of a natural swelling matrix derived from boat-fruited sterculia seed (SMS) as the propellant of osmotic pump tablets. The sugar components, static swelling, water uptake and viscosity of SMS were determined and compared with that of polythylene oxide (WSR-N10 and WSR-303). Both ribavirin and glipizide were used as water-soluble and water-insoluble model drugs. Then, the monolayer osmotic pump tablets of ribavirin and the bilayer osmotic pump tablets of glipizide were prepared using SMS as the osmotically active substance and propellant. SMS was mainly composed of rhamnose, arabinose, xylose and galactose and exhibited relatively high swelling ability. The area of the disintegrated matrix tablet was 20.1 times as that at initial after swelling for 600 s. SMS swelled rapidly and was fully swelled (0.5%) in aqueous solution with relative low viscosity (3.66 +/- 0.03) mPa x s at 25 degrees C. The monolayer osmotic pump tablets of ribavirin and the bilayer osmotic pump tablets of glipizide using SMS as propellant exhibited typical drug release features of osmotic pumps. In conclusion, the swelling matrix derived from boat-fruited sterculia seed, with low viscosity and high swelling, is a potential propellant in the application of osmotic pump tablets.