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Objective To establish assay methods for the determination of dissolution,content and related substances of vita-min K1 self-nanoemulsifying drug delivery system(VK1-SNEDDS),and investigate the physico-chemical properties of the preparation. Methods The UV method was established to determine the dissolution of VK1-SNEDDS. The content and related substances were de-termined by HPLC. The appearance,self-emulsification time,micro-morphology,droplet size and zeta potential were also investigat-ed. Results The linearity range of established UV and HPLC methods was 0.85-20.4 and 2.16-216μg/ml,respectively,and all the recovery,precision,specificity and sensitivity met requirements. VK1-SNEDDS could disperse quickly after dilution. The transmission electron microscope(TEM)image of the optimized liquid SNEDDS showed that most of the emulsion droplets were of uniform size with no signs of coalescence. Droplet size of optimal formulation was revealed as 47.74 nm with polydispersibility index(PDI)of 0.248,and zeta potential was found to be-20.53 mV. Conclusion VK1-SNEDDS could form homogeneous and stable nanoemulsion when dilut-ed with aqueous phase and increase the dissolution of lipophilic drug. The methods are reliable,accurate and suitable for quality con-trol of VK1-SNEDDS.
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[Abstact] Objective To study the preformulation properties of tecovirimat for formulation design. Methods The appear?ance,crystal structure,solubility and permeability of the drug were investigated. The UV method was established to determine the con?tent of tecovirimat in vitro. The solubilization experiment was also conducted. Results Tecovirimat is white and odorless powder with crystalline hydrate structure and low water-solubility with high permeability. The morphology of tecovirimat is six-prismatic-shape. The linearity range of established UV method was 4.14-24.83μg/ml(r=0.9996). The 1∶1 soluble complex was formed with tecovirimat and hydroxypropyl-β-cyclodextrin. Conclusion Tecovirimat is poorly water-soluble drug with high permeability and the established meth?od could be used to determine the content of the drug. Hydroxypropyl-β-cyclodextrin could be used for the solubilization of tecovirimat.
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Objective To explore the combined detection of B‐type natriuretic peptide (BNP) and glycosylated antigen 125 (CA125) in differential diagnosis of dyspnea .Methods BNP and CA125 were detected and compared among 106 cases with cardiac dyspnea ,56 cases with pulmonary dyspnea and 60 healthy subjects .Results BNP and CA125 levels of dyspnea patients were higher than healthy subjects ,and those of cardiac dyspnea patients were higher than pulmonary dyspnea patients (P<0 .05) .With the ag‐gravation of heart failure ,BNP and CA125 levels gradually increased .Combined detection of BNP and CA125 were with higher diag‐nostic sensitivity and specificity (P<0 .05) .After treatment ,BNP and CA125 levels significantly decreased (P<0 .05) .Conclusion Combined detection of BNP and CA125 could be with high specificity and sensitivity ,helpful for identifying cardiac or pulmonary dyspnea and dynamic observation of the disease .
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Objective To establish an HPLC method for determination of related substances of dexmethylphenidate hydrochloride and their content .Methods The HPLC method was used on an Agilent ZORBAX SB-C18 column with a mo-bile phase of methanol-0.2%triethyl citrate in 25 mmol/L potassium dihydrogen phosphate ( pH was adjusted to 3.5 with phosphoric acid) (35∶65) at a flow rate of 1.0 ml/min.The detection wavelength was 209 nm and column temperature was 40℃.Results Under the selected chromatographic condition , dexmethylphenidate hydrochloride was completely separated from impurity.The limit of detection was 81.12 ng/ml.The calibration curve was linear in the range of 2-30 μg/ml ( r=0.9995).The average recovery of the method was 100.83%, and the stability of the working solution was acceptable in 12 h(RSD=0.10%).Conclusion This method is simple,specific,accurate and suitable for analyzing the related substances and their content in dexmethylphenidate hydrochloride .
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Objective To optimize the formulation of metoprolol succinate ( MS) controlled release pellets by central composite design-response surface methodology .Methods MS sustained-release pellets were prepared using sugar pellet cores as starter beads , ethyl cellulose as coating materials and MS itself as a pore former .The formulation of MS sustained-release pellets was optimized by a central composite design with two factors at five levels .These two factors ( two independ-ent variables) were the pore former level and coating level , and the evaluated indexes ( namely dependent variables ) included the in vitro cumulative release percentages of MS at 1, 4, 8, 12 and 16 h, respectively.Results and Conclusion The results of mathematical equation fitting suggested that the second-order quadratic model was the optimal fitting equa-tion.According to the response surfaces , the optimum values at the pore former level and coating level weve ranged from 16%to 18%and 20% to 25%, respectively .The in vitro cumulative release percentage of MS from the pellets at 1 h reached 9.15%,which consequently eliminated the lag phase in the initial release period and exhibited a good sustained-release effect.Central composite design-response surface methodology can be applied to optimizing the coating formulation for MS sustained release pellets .
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Objective To study the effect of surfactants on the dissolution profiles of poorly water-soluble acidic drug nimesulide from sustained-release tablets.Methods The anionic surfactant sodium dodecyl sulfate (SDS), cationic sur-factant cetyltrimethyl ammonium bromide (CTAB) and nonionic surfactant polysorbate 80 (Tween 80) were used to prepare nimesulide micelles .The effect of the buffer , surfactant and ionic strength on the equilibrium solubility of the drug and the in vitro release of sustained-release tablets was studied .Results and Conclusion In pH 1.2 HCl solution, water and pH 6.8 phosphate buffer, the solubilization capacity of CTAB was the highest.However, in pH 9.0 Tris buffer, when CTAB concen-tration was at about 1%, the equilibrium solubility of nimesulide was at the trough value .The in vitro release results were similar to those of equilibrium solubility and the kinetic pattern conformed to the first order equation according to the coefficient R .