Isotretinoin (13-cis retinoic acid, ITT) is a gold standard therapy for the treatment of severe acne. However, because of its poor absorption, ITT must be taken with fatty meals to increase bioavailability. The coadministration of food could reduce the compliance of patients and increase the risk of inconsistent serum levels because of different eating habits. In this work, we designed and synthesized four cocrystals of ITT. The cocrystal between ITT and ethyl nicotinate (ENT), namely, ITT-ENT, presented better chemical stability, dissolution, and absorption than ITT itself. The AUC 0−10h of ITT-ENT cocrystal capsules is 2.6 times as that of the commercially available ITT capsules in the fasted state. Because of the high bioavailability in the fasted state, the food has a marginal effect on the absorption of cocrystal capsules. This work sets a good example for applying cocrystal technology to enhance the absorption and mitigate the food effect of drugs.

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In order to simulate the structural vibration and acoustic field in time domain, we discuss the calculation method of the structural damping and provide an integrated numerical method for impact sound synthesis which is finally well verified experimentally. Firstly, since the damping is considered to be one of the factors influencing the time-varying characteristics of the transient vibration, the detailed information are obtained by both of modal damping calculating methods. Secondly, the vibration and sound radiation of damping impacted plates are simulated in the time domain, showing that they are highly consistent with the results from the finite-difference time-domain method. Finally, the comparison between the impact sound of the finite cylindrical shell and the experimental results is performed, indicating that the two sounds are much the same in the temporal envelope, spectral structure and decay trend. What is more, the results imply that it is quite effective to use the these numerical methods to synthesize impact sounds.