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OBJECTIVE To evaluate the palatability and chewability of chewable tablets， and provide reference for the quality evaluation of various types of chewable tablets. METHODS Using self-made Glucosamine hydrochloride chewable tablets as the model drug， the quality test was conducted. The in vitro simulation system for chewable tablets was established by using a texture analyzer and rheometer， and an oral simulation experiment was conducted on chewable tablets. The texture analyzer was used to measure the force required for chewing and simulate the static disintegration process of chewable tablets； the rheometer was adopted to measure the viscoelasticity， thixotropy， and deformability of chewable tablets during the chewing process. RESULTS The disintegration time limit， principal component content， and dissolution of self-made Glucosamine hydrochloride chewable tablets all met the limit requirements. The in vitro simulation results of the texture analyzer showed that self-made chewable tablets were easy to chew in both axial and radial directions， and the force required for chewing was within the range of the chewing force of the teeth； chewable tablets could disintegrate at an appropriate time without being chewed and only taken in the oral cavity. The in vitro simulation results of the rheometer showed that the chewable tablets in the oral cavity exhibited a behavior of elasticity as the main factor and viscosity as the secondary factor through the continuous stirring of the tongue， and the viscosity of the chewable tablets gradually decreased with tongue stirring or tooth chewing； when chewing with teeth， the internal force of the chewing tablets decreased， causing plastic deformation and crushing. After being crushed， the shape couldn’t be restored， making it easy to chew and swallow. CONCLUSIONS The combination of texture analyzer and rheometer can be used to simulate the oral chewing process and evaluate the palatability and chewability of self-made Glucosamine hydrochloride chewable tablets. This model can provide reference for the evaluation of various chewable tablets.
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Objective To analyze mechanical properties of stent retrievers with different structures, and provide theoretical support for the design and clinical selection of stent retrievers. Methods Three kinds of stent retrievers with different structures (B3, K4, X) were evaluated by finite element analysis and in vitro simulation experiment. The analytic parameters were radial support force, withdrawal force and thrombosis state during the thrombotomy test. Results The radial support forces of B3, K4, X stent retrievers obtained from the experiment were 0.48 N, 0.43 N, 0.51 N, respectively. The larger the crimping distance, the greater the radial support force of stent retrievers. The radial support force of the stent increased significantly when the crimping distance was larger than 3 mm. The simulated thrombus removal experiment results showed that the peak withdrawal forces of B3, K4, X stent retrievers were 0.410 N, 0.451N, 0.501 N, respectively. The experimental results were consistent with the finite element analysis results. Conclusion sBoth the experimental results and the finite element results showed that the X stent has better mechanical properties. This method can be used as an analytic method to evaluate performance of the stent retrievers, and provide references for performance improvement and development of the stent retrievers.
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Objective To evaluate the influence of Circle of Willis on intravascular hypothermia. Methods A patient-specific model of the Circle of Willis was constructed based on the CT images and the in vitro perfusion experiment with cold water for 20 ℃ was performed. The water was injected from right intracarotid artery (ICA) to the area of middle cerebral artery (MCA) at the flow rate of 30 mL/min and made the cooling period last 15 min. The cooling and rewarming characteristics in the phantom and fluid around MCA were investigated using thermocouples arranged at 27 and 1 spatial locations. The areas distributed with cold water were further visualized using the dyed solution. Results The cold water from right ICA was mainly distributed to right anterior cerebral artery (ACA), MCA, and posterior communicating artery (PCoA), while only a little part of the water could possibly pass through anterior communicating artery (ACoA) to the left ACA. The nearer the locations to the area with cold water, the faster cooling down and also faster temperature recovery rate would be obtained. Moreover, the phantom temperature distributions were asymmetric around MCA due to the complicated bifurcation structures in this area. Conclusions This physical model is useful for investigating the influence of vasculature on endovascular hypothermia and applicable in designing patient-specific hypothermia therapy.