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Background: Chuankezhi injection (CKZ) is a traditional Chinese medicine for the treatment of respiratory diseases and has been often used off-label as a nebulization therapy. However, little is known about the aerosolization performance and pulmonary fate of the inhaled CKZ. This study aimed to evaluate the aerodynamic characteristics of nebulizer generated aerosols and to compare the properties of pharmacokinetics, lung distribution and anti-inflammation effects of CKZ after intratracheal and intravenous administration. Methods: The nebulization performance was evaluated in vitro based on the aerodynamic particle size distribution and aerosol output. The concentrations of epimedins A, B, C and icariin, the main active ingredients of CKZ, in plasma, bronchoalveolar lavage fluids (BALF) and lung tissues were measured by LC-MS/MS analysis. The pulmonary anti-inflammatory efficacy were tested using LPS-induced pulmonary inflammation mice model as indicated by the total cells counts, and the levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in BALF. Results: The aerosols of CKZ generated by a commercial nebulizer showed excellent aerodynamic properties and delivery output. Following intratracheal instillation of CKZ, epidemins A, B and C, and icariin, were absorbed into the bloodstream with the mean absorption time varying from 101.8 min to 271.8 min, and their absolute bioavailabilities ranging from 26.4 % to 104 %. The instillation of CKZ increased the lung to plasma concentration ratios by 25.5–718 folds compared to intravenous administration, leading to improved and prolonged local anti-inflammatory effects. Conclusion: Nebulization therapy of CKZ could be a promising alternative to the injectable counterpart.

Self-microemulsifying (SME) drug delivery system has been developed to increase oral bioavailabilities, and inhibitory excipients are capable of improving oral bioavailability by inhibiting enzyme mediated intestinal metabolism. However, the potential of enzyme inhibitory excipients containing SME in boosting resveratrol bioavailability remains largely uninvestigated. In this study, we set out to prepare SME-1 with UGT inhibitory excipients (excipients without inhibitory activities named SME-2 as control) to increase the bioavailability of RES by inhibiting intestinal metabolism. Results demonstrated that similar physicochemical properties such as size, polydistribution index and in vitro release, cellular uptake and permeability in Caco-2 cells as well as in vivo lymphatic distribution between inhibitory SME-1 and non-inhibitory SME-2 were observed. In vivo study demonstrated that the molar ratios of RES-G/RES were 7.25 ± 0.48 and 5.06 ± 2.42 for free drug and SME-2, respectively, and the molar ratio decreased to 0.36 ± 0.10 in SME-1 group. Pharmacokinetic study confirmed that the inhibitory excipients containing SME demonstrated potential in increasing bioavailability of RES from 6.5% for the free RES and 12.9% for SME-2 to 76.1% in SME-1 through modulating the glucuronidation by UGT inhibitory excipients. [ABSTRACT FROM AUTHOR]

• SME-1 improved in vitro release, cellular uptake, and transport. • SME-1 decreased the production of phase II metabolite, CSA-G. • Inhibitory SME-1resulted in significantly higher oral bioavailability. • Enhanced oral bioavailability attributed to the inhibition of glucuronidation. Cajaninstilbene acid (CSA) exerts wide pharmacological activities, such as anti-inflammation, hypoglycaemic activity, analgesic effect and cognition improvement. However, it underwent severe phase II metabolism mediated by UDP-glucuronosyltransferase (UGT) in the gastrointestinal (GI) tract after oral administration, affecting its oral bioavailability. In the present study, we utilize UGT inhibitory excipient containing self-microemulsion (SME) delivery system to reduce the production of glucuronide metabolites and increase its oral bioavailability. The present results showed that although similar properties in physiochemical, cytotoxicity, cellular uptake, absorption and transport across rat everted gut sacs between SME-1 (inhibitory excipient containing SME) and SME-2 (control SME, without inhibitory excipient), an improved absolute bioavailability of 57.3 % was conferred by SME-1, significantly higher than the value of 35.4 % by SME-2 and 34.0 % by free CSA. Noticeably, the significantly lower AUC value of CSA glucuronide was determined in rats treated with SME-1 than those either treated with SME-2 or free CSA. Thus, the ability of SME-1 to enhance oral bioavailability of CSA is mainly attributed to the inhibition of phase II metabolism in the GI tract. [ABSTRACT FROM AUTHOR]