Spironolactone, a class Ⅱ drug of the biopharmaceutics classification system, has low oral bioavailability due to poor solubility. Spironolactone solid dispersions were prepared using the solvent method in order to improve its aqueous solubility. Optimization studies of spironolactone solid dispersions were performed using in vitro dissolution tests. Differential scanning calorimetry, X-ray diffraction and Fourier transform infrared were used to investigate the physical state of the drug in carrier materials and to detect the possible interactions between the drug and carrier materials in the solid dispersions. In addition, stress tests were employed to elucidate the key factors which have influence on the stability of the spironolactone solid dispersions. Results showed that spironolactone in the solid dispersions formulated with Soluplus and HPMC-E5 were both in amorphous state and the hydrogen bonds between the drug and carrier materials were formed in the solid dispersion. Therefore, the in vitro dissolution of spironolactone was also significantly enhanced. Stress tests demonstrated that the physical stability of spironolactone solid dispersions prepared with Soluplus was greatly improved compared to those formulated with HPMC-E5. Thus, spironolactone solid dispersion formulated with Soluplus using the solvent method could be used to improve the in vitro dissolution and stability of poorly soluble drugs.

Cyclodextrin can increase the solubility of poorly soluble drugs, but also decrease the permeability of poorly soluble drugs in inclusion complexes simultaneously, which partially or completely counteracts the contribution of improvement in solubility to the oral absorption of poorly soluble drugs. If a competing agent is added to the system to compete binding sites of cyclodextrins with drugs, drug permeability can be improved by increasing the concentration of free drugs in the inclusion complex system. In this paper, a rapid in vitro screening method for competing agents of cyclodextrin inclusion complex is proposed based on the principle that good drug permeability is in accord with good cell uptake. The equilibrium constants between drugs and hydroxypropyl-beta-cyclodextrin (HPCD) were determined by phase equilibrium solubility method. Cinnarizine (CN) with a high equilibrium constant was selected as a competing agent, coumarin 6 (C6) and 9-octadecyl berberine (BD) with smaller equilibrium constants were selected as model drugs. Both changes of solubility and uptake by Caco-2 and A549 cells of C6 and BD were investigated different concentrations of CN to the HPCD solution of C6 and BD. The results showed that the uptake of C6 and BD increased in a CN concentration-dependent manner, and the solubility of C6 and BD in HPCD solution decreased with the prolongation of equilibrium time. It might be due to increased free drug concentrations that resulted from the competition of CN for drug binding sites with HPCD. In our study, in vitro cell uptake method was firstly used to validate the ability of CN as a competing agent to increase drug permeability (cell uptake). This method can be used for preliminarily screening of competing agents for drug-cyclodextrin inclusion complexes.

The objective of this paper was to establish a level A in vitro-in vivo correlation (IVIVC) for goserelin acetate extended release microspheres for injection. Three kinds of goserelin acetate microspheres with different release rates were prepared and the critical physicochemical properties, such as drug loading, particle size, glass transition temperature and morphology were characterized. In vitro dissolution test of the prepared goserelin acetate microspheres was performed using sample-and-separate method at 45℃ in 5% (v/v) methanol. The morphology of the microspheres and the molecular weight of poly (lactic-co-glycolic acid) (PLGA) of the prepared goserelin acetate microspheres were investigated to research the release mechanism of microspheres. The plasma concentration of goserelin was detected after intramuscular injection of goserelin acetate microspheres to SD rats, and correlated with the in vitro release profiles after processing by percent AUC method. The pharmacokinetic experimental protocol of goserelin acetate microspheres for injection in SD rats was approved by the Animal Ethics Committee of Shandong Luye Pharmaceutical Co., Ltd. The results indicated that the developed sample and separate method was able to detect differences in the release characteristics of the prepared goserelin acetate microspheres, and the in vitro-in vivo correlation of goserelin acetate microspheres was excellent (r > 0.98) and had good predictive ability in SD rats.

The aim of this study is to investigate the influence of flufenamic acid (FFA) on the solubility, dissolution and bioavailability of sorafenib (SFN) in the combined administration of the MSNM@SFN and FFA. The MSNM@SFN&FFA was prepared by mixing the MSNM@SFN with FFA. The solubility, dissolution and bioavailability of SFN in the MSNM@SFN&FFA complex was investigated in comparison with those of the MSNM@SFN. This study was performed following the National Institutes of Health guidelines for the use of experimental animals; all care and handling of animals were performed with the approval of the Experimental Animal Center of Peking University Health Science Center. The MSNM@SFN&FFA showed no significant influence on the solubility, dissolution and bioavailability of SFN when compared with the MSNM@SFN. These data indicated that FFA had almost no influence on the solubility, dissolution and bioavailability of SFN in the combined administration of MSNM@SFN and FFA, thus providing an experimental foundation for the subsequent formulation research on the combined usage of drugs.

Monoclonal antibodies (mAbs) have been widely used as therapeutic drugs for treating diseases such as cancers and auto-immune diseases. When using an IgG4 isotype, one of the challenges is the instability of its hinge which is prone to Fab-arm exchange (FAE). The hinge sequence of a wild type IgG4 is -CPSC-, however, a single point mutation S228P from -CPSC-to -CPPC-can effectively diminish FAE, thereby improving hinge stability of the IgG4 molecule. Sintilimab is the fully human anti-PD-1 monoclonal antibody designed and developed for immuno-oncology, in which serine 228 in the hinge was engineered to proline to mitigate FAE. In this study, LC-MS is used to study hinge stability of sintilimab in both in vitro (PBS and human serum) and in vivo (SCID mouse) studies. The studies demonstrate that LC-MS is a fast and simple way to monitor for the occurrence of FAE in vitro and in vivo, and FAE can be eliminated by antibody engineering with a single point mutation.

The aim of this study is to prepare porous γ-cyclodextrin metal-organic framework (CD-MOF) with good biocompatibility to improve the in vitro release properties of water-insoluble drugs. Different sizes of CD-MOF were obtained by controlling the self-assembly of γ-cyclodextrin and potassium ion and the rate of crystal growth. The poorly water-soluble diflunisal (DIF) was selected as the model drug and loaded into the interior of porous CD-MOF by the impregnation method. The DIF loaded CD-MOF (DIF-MOF) was characterized by scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), nitrogen adsorption and desorption, Fourier infrared spectrometer and thermogravimetric analysis. In addition, in vitro cytotoxicity and solubilizing capability of CD-MOF were investigated. It revealed that the obtained CD-MOF was cubic-like with a narrow size distribution and high porosity. Negligible cytotoxicity was found after incubation with RAW264.7 cells. Compared with the pure CD-MOF carrier, the morphology and crystal form of DIF-MOF was not damaged during the drug loading process. Moreover, the solubility and release rate of water-insoluble DIF from the DIF-MOF were significantly increased.

The solubilization and protection of curcumin (Cur) by mixed surfactants were studied through the determination about the critical micellar concentration (CMC) of the mixed surfactants of Tween 80 and dodecyl trimethyl ammonium bromide (DTAB), molar solubilization ratio (MSR), degradation rate (k) of Cur in pH 13 solution and mixed surfactant solutions prepared at pH 13. The results showed that when Tween 80 was used alone, it exhibited high solubilization ability but poor stability. DTAB was used alone, it showed strong stability but poor solubilization ability. When DTAB was mixed with Tween 80 at different mole fractions, the stability of Cur was enhanced, and the best stability was observed when the mole fraction of DTAB was 0.4, although the solubilization ability was not the best at this mole fraction, but MSR was increased by 1.7 times compared to DTAB used alone. Mixed surfactant not only increased the solubility but also improved the stability of Cur. In addition, mixed surfactant has the advantages of less dosage and low toxicity, which is worth popularizing in application.

Using silica gel column chromatography, gel chromatography and HPLC, we isolated secondary metabolites in fermentation broth of a rifamycin resistant mutation strain Streptomyces sp. HS-NF-1046R. Based on spectroscopic data, the chemical structures of three compounds were identified as 3-hydroxyl-2-N-propionyl-anthranilamide (1), 2, 3-dihydro-8-hydroxy-2, 2-dimethyl quinazolin-4-(1H)-one (2) and 2-aminobenzamide (3). Compounds 1 and 2, as new entities, were evaluated for cytotoxicity against A549, HepG2, HCT-116 and K562 cells using the SRB assay. Compounds 1 and 2 exhibited no cytotoxicity with IC₅₀ over 100 μmol·L^-1.

G protein-coupled receptors (GPCR) are a class of receptor superfamily that exist on the surface of cell membrane. With the intensive studies on the GPCR desensitization regulator-β-arrestins, it is found that activated GPCR can not only conduct signal transduction through G protein-dependent pathway, but also mediate via non-G protein-dependent pathway. In addition to mediate endocytosis and desensitization, β-arrestins also initiate a new series of signal transduction events. Therefore, the concept of "biased transduction" was put forward:the receptor activated by a specific ligand could selectively activate a specific signaling pathway, leading the signal to be transmitted downstream along a "preferential" pathway. We call the ligand that binds to the receptor and causes biased activation "biased ligand". It is generally believed that the phenomenon of bias results from different binding modes of ligands and receptors, including multiple receptor conformations, diverse sites that downstream signal proteins bind, and signal proteins' own conformations, etc. Here we give a brief review focusing on the mechanisms of β-arrestin-biased GPCR signal transduction and the advances in the drug development on β-arrestin biased ligands.

Artemisinin and its derivatives have been proved for their anti-tuberculosis activities, despite its low water solubility which hampered its efficacy and corresponding formulation development. In this study we designed and synthesized a novel artemisinin analog by conjugating an arginine through a succinic acid linker. This design not only enhanced the water solubility of the artemisinin, but also increased the efficacy of the molecule towards tuberculosis bacteria due to disruption by arginine. The results showed that the solubility of the synthesized derivatives A-2 and A-3 increased 19.8-27.8 folds compared to artemisinin. In vitro cytotoxicity experiment showed that compound A-3 had negligible toxicity to THP-1 cells up to 1 mg·mL^-1, the minimal inhibitory concentration (MIC) of A-2 and A-3 was 20 and 10 μg·mL^-1, respectively, which was 5 or 10 times lower than that of artemisinin. Intracellular bacteria inhibition experiment showed that compound A-3 at lower concentrations such as 100 or 200 μg·mL^-1 significantly inhibited the growth of tuberculosis bacteria (P < 0.05 or P < 0.01), which efficacy was stronger than artemisinin at the concentration of 100 μg·mL^-1. These results strongly suggested that compound A-3 was a potential anti-tuberculosis lead compound.