Background/Objectives: Numerical simulation plays an important role in pharmaceutical preparation recently. Mechanistic models, as a type of numerical model, are widely used in the study of pharmaceutical preparations. Mechanistic models are based on a priori knowledge, i.e., laws of physics, chemistry, and biology. However, due to interdisciplinary reasons, pharmacy researchers have greater difficulties in using computer models. Methods: In this paper, we highlight the application scenarios and examples of mechanistic modelling in pharmacy research and provide a reference for drug researchers to get started. Results: By establishing a suitable model and inputting preparation parameters, researchers can analyze the drug preparation process. Therefore, mechanistic models are effective tools to optimize the preparation parameters and predict potential quality problems of the product. With product quality parameters as the ultimate goal, the experiment design is optimized by mechanistic models. This process emphasizes the concept of quality by design. Conclusions: The use of numerical simulation saves experimental cost and time, and speeds up the experimental process. In pharmacy experiments, part of the physical information and the change processes are difficult to obtain, such as the mechanical phenomena during tablet compression and the airflow details in the nasal cavity. Therefore, it is necessary to predict the information and guide the formulation with the help of mechanistic models.

Paeoniflorin is a natural pharmaceutical ingredient with a widely biological activity. However, as a hydrophilic drug, the problem of low transdermal rate limits its clinical application. To overcome this shortage, LUVs were used as biocompatible carriers of paeoniflorin in this study. We prepared paeoniflorin-loaded large unilamellar vesicles (LUVs) with W/O/W structure by microfluidics. We used four kinds of chips to prepare paeoniflorin LUVs and explored the effects of the chip structures on LUVs properties applying both experiments and numerical simulations. The difference of fluid mixing mechanisms was analyzed among four different channels, including straight and curved structures. Then we evaluated the differences in skin permeability among the three groups, paeoniflorin aqueous solution group, drug-loaded liposome group and blank liposome & drug mixture group, using the abdominal skin of male mice. The results showed that the structure of the microfluidic channel was a key factor affecting the flow rate and mixing efficiency. The mixing efficiency further affected the liposome size. The mixing efficiency of curved channel was not better than that of a straight channel due to the low flow rate and long mixing time. By the results of transdermal experiments, LUVs could reduce the transdermal time and increase the total transdermal amount. LUVs effectively improved the transdermal absorption efficiency of paeoniflorin. In conclusion, paeoniflorin LUVs with highly efficient transdermal were successfully prepared by using microfluidics. We explored the underlying fluid dynamics that lead to variations in the preparation with different chip structures. The transdermal effect of the LUVs was verified. Graphical Abstract

To establish a method to determine the dissolution of Tanshinone IIA in xianling gubao capsules, and compare the dissolution of Xianling Gubao capsules prepared by different processes. The small cup method was used at a rotary speed of 100 r x min(-1), the dissolubility was inspected in the following 6 mediums: (1) water; (2) 0.1 mol x L(-1) hydrochloric acid solution; (3) pH 6.8 phosphate buffer; (4) pH 6.8 phosphate buffer solution + 0.5% cholic acid; (5) pH 6.8 phosphate buffer solution + 1.0% cholic acid; (6) pH 7.6 phosphate buffer solution + 4. 0% cholic acid. A HPLC method was used to determine the dissolution samples of tanshione IIA in different dissolution mediums. The accumulative dissolution percentages were calculated, and the resemblance of release curves were compared by similarity factors (f2). The accumulative dissolution percentage was the highest while pH 7.6 phosphate buffer solution + 4.0% cholic acid was used as medium. The similarity factor values (f2) of tanshinone IIA dissolution curves of different preparation processes of Xianling Gubao capsules were all less than 50. There is significant difference in tanshinone IIA dissolution between Xianling Gubao capsules of different preparation processes. The accumulative dissolution percentages of the tanshinone IIA in new Xianling Gubao capsules is higher than that in the capsules prepared by other preparation processes.