ABSTRACT
Sacubitril valsartan sodium (LCZ696) is an ionic cocrystal drug. The purpose of this study was to explore the cocrystal features of LC696 by establishing a variety of characterization methods, and thus provide basic research data for effective quality control. The cocrystal characteristics of LCZ696 and its tablets were identified by applying analytical means including powder X-ray diffraction (PXRD), fourier transform infrared spectroscopy (FTIR), Raman spectra (RM), differential scanning calorimetry (DSC) and solid-state nuclear magnetic resonance spectroscopy (ssNMR). The crystalline water and hygroscopicity of LCZ696 were analyzed by thermogravimetric analysis (TGA), dynamic vapor sorption (DVS), hygroscopicity test and Karl Fischer reaction method. The results show that PXRD, FTIR, DSC and ssNMR can effectively distinguish the features of LCZ696 cocrystal, sacubitril monomer, valsartan monomer, and sacubitril-valsartan (1∶1) mixture. RM can be used as a supplementary approach. Combined with the analysis by TGA, DVS, hygroscopicity test and Karl Fischer reaction method results, LCZ696 contains 2.5 crystalline water molecules and is very hygroscopic; we recommend that LCZ696 be stored in an environment with a relative humidity below 60%. By characterizing the crystal features we can establish quality control measure and evaluate the stability of the drug tablets. This study provides data in support for the establishment of the LCZ696 quality standard.
ABSTRACT
Bexarotene is a synthetic analogue of retinoic acid and exerts protective effects on the nervous system. However, low bioavailability and poor solubility of the crystal type I form severely limits the application of bexarotene in the clinic. A co-amorphous sample of bexarotene-PVP-K30 was prepared and the structure was characterized by X-ray diffraction and infrared spectroscopy. To determine the pharmacokinetics and tissue distribution of bexarotene, an LC-MS method was established to profile and quantify bexarotene in plasma and tissues of SD rats. In vitro dissolution indicated that the co-amorphous form improved the dissolution of bexarotene in pure water 4.17-fold. After rats were orally administered bexarotene or bexarotene-PVP-K30 co-amorphous (equivalent to 30 mg·kg-1 bexarotene) the AUC of bexarotene was 7 034.89 and 10 174.03 μg·L-1·h respectively, the peak time was advanced from 7.33 h to 0.9 h with the amorphous form, and Cmax was enhanced from 627.76 to 3 011.88 μg·L-1. The co-amorphous form yielded higher concentrations of bexarotene in various tissues, especially brain, liver and kidney. Animal welfare and experimental procedures complied with the rules of the Animal Ethics Committee of the Institute of Materia Medica, Chinese Academy of Medical Sciences. The results indicate that bexarotene-PVP-K30 co-amorphous improves the pharmacokinetic characteristics of bexarotene and provides preclinical data in support of bexarotene-PVP-K30 for the treatment of brain diseases.
ABSTRACT
The certified reference materials (CRMs) of emodin in rhubarb and its alcohol extract, water extract were developed by using quantity transfer technology from single chemical composition to the complex systems. The CRM of emodin was used for quantity transfer, and high performance liquid chromatography (HPLC) method was used to determine the contents of emodin in different matrix composition. By establishing mathematical model and calculating the parts of uncertainty, the uncertainty values were finally gotten. CRMs of emodin in rhubarb, alcohol extract and water extract were accomplished. The content values of emodin were 0.40% ±0.03%, 1.15%±0.18%, 0.16%±0.08% (k=2,P=0.95), respectively. The established method for quantity transfer has successfully solved the technical problems that the value of active ingredient of traditional Chinese medicine can't be traced to SI units. The series of CRMs are assigned as grade primary reference materials, which are useful for quality control of the emodin content, also provide the accurate and reliable CRM, materials standard and standard methods.