A Non-Lipolysis Nanoemulsion Improved Oral Bioavailability by Reducing the First-Pass Metabolism of Raloxifene, and Related Absorption Mechanisms Being Studied.

OBJECTIVE: A non-lipolysis nanoemulsion (NNE) was designed to reduce the first-pass metabolism of raloxifene (RAL) by intestinal UDP-glucuronosyltransferases (UGTs) for increasing the oral absorption of RAL, coupled with in vitro and in vivo studies. METHODS: In vitro stability of NNE was evaluated by lipolysis and the UGT metabolism system. The oral bioavailability of NNE was studied in rats and pigs. Finally, the absorption mechanisms of NNE were investigated by in situ single-pass intestinal perfusion (SPIP) in rats, Madin-Darby canine kidney (MDCK) cells model, and lymphatic blocking model. RESULTS: The pre-NNE consisted of isopropyl palmitate, linoleic acid, Cremophor RH40, and ethanol in a weight ratio of 3.33:1.67:3:2. Compared to lipolysis nanoemulsion of RAL (RAL-LNE), the RAL-NNE was more stable in in vitro gastrointestinal buffers, lipolysis, and UGT metabolism system (p < 0.05). The oral bioavailability was significantly improved by the NNE (203.30%) and the LNE (205.89%) relative to the suspension group in rats. However, 541.28% relative bioavailability was achieved in pigs after oral NNE intake compared to the suspension and had two-fold greater bioavailability than the LNE (p < 0.05). The RAL-NNE was mainly absorbed in the jejunum and had high permeability at the intestine of rats. The results of both SPIP and MDCK cell models demonstrated that the RAL-NNE was absorbed via endocytosis mediated by caveolin and clathrin. The other absorption route, the lymphatic transport (cycloheximide as blocking agent), was significantly improved by the NNE compared with the LNE (p < 0.05). CONCLUSION: A NNE was successfully developed to reduce the first-pass metabolism of RAL in the intestine and enhance its lymphatic transport, thereby improving the oral bioavailability. Altogether, NNE is a promising carrier for the oral delivery of drugs with significant first-pass metabolism.

Study on Detection Methods for Related Substances in Fidaxomicin Raw Material / 中国药房

OBJECTIVE：To establish th e method for the determination of related substances in fidaxomicin raw material. METHODS：The detection ability of NP-HPLC-UV ，RP-HPLC-ELSD and RP-HPLC-UV systems for the related substances in fidamycin raw material was investigated and the best chromatographic system was selected . The HPLC detection method for the related substances was established. The detection was performed on Agilent Eclipse XDB C 18 column with mobile phase A consisted of 0.2％ triethylamine buffer solution （pH 3.8）-acetonitrile（55∶45，V/V），mobile phase B consisted of 0.2％ triethylamine buffer solution（pH 3.8）-acetonitrile（20∶80，V/V）at the flow rate of 1.0 mL/min（gradient elution ）；the detection wavelength was set at 230 nm，and column temperature was 35 ℃；the sample size was 10 µL. Calculation of the content of related substances was principal component self-control method without correction factor. RESULTS ：The impurities C and F could not be separated effectively in NP-HPLC-UV system. In RP-HPLC-ELSD system ，only impurities C ，D，E and F could be detected. In RP-HPLC-UV system ，11 impurities could be detected. In the study of methodology ，the linear ranges were 0.5-20.0 μg/mL for fidaxomicin（R2＝0.999 9）；the LOD was 0.05 ng，LOQ was 0.15 ng；RSDs of reproducibility and intermediate precision tests were less than 2.0％（n＝6）；average recovery was 98.4％（RSD＝3.6％，n＝9）. The sum of impurities in 3 batches of raw materials were 0.53％，0.51％，0.51％，respectively. CONCLUSIONS ：The effect of detecting impurities by RP-HPLC-UV are the best. Established method is specific and sensitive ，and can be used for the determination of related substance in fidaxomicin raw material.