Cheng-jie Wu

Bio: Cheng-jie Wu is an academic researcher from Zhejiang International Studies University. The author has contributed to research in topics: Thermal decomposition & Decomposition. The author has an hindex of 4, co-authored 5 publications receiving 26 citations.

Thermal decomposition mechanism of tenofovir disoproxil fumarate

Abstract: Tenofovir disoproxil fumarate (TDF) is an antiretroviral medication widely used to prevent and treat HIV/AIDS and to treat chronic hepatitis B. In this paper, thermal decomposition processes of TDF were measured with thermogravimetry, differential scanning calorimetry and thermogravimetric analysis coupled with Fourier transform infrared spectroscopy. The IR spectra, high-performance liquid chromatography and liquid chromatography mass spectrometry of TDF and the residues of its thermal decomposition at various temperatures were determined. The molecular bond orders were calculated using an ab initio method from the GAMESS program of quantum chemistry. The mechanism of thermal decomposition was discussed. The results indicated that the thermal decomposition of TDF is a three-step process, the initial step of thermal decomposition of TDF is the decomposition of carboxylic ester, the first stage mainly is the decomposition of the phosphoric disoproxil section, and the second stage mainly is the decomposition of the tenofovir section and partially goes through adenine stage. The initial decomposition temperature in either nitrogen or air is 138 °C, and the thermal stability of TDF is not very good under routine temperature.

Thermal decomposition mechanism of piroxicam

Abstract: Piroxicam (PRX) is a nonsteroidal anti-inflammatory drug. The thermal decomposition process of PRX was investigated with thermogravimetry and differential scanning calorimetry. The gaseous products generated by thermal decomposition were characterized with thermogravimetric analysis coupled with Fourier transform infrared spectroscopy. The residues of the thermal decomposition at various temperatures were identified with infrared spectroscopy. The molecular bond orders were calculated using an ab initio method from the GAMESS program of quantum chemistry. The mechanism of thermal decomposition for PRX was discussed. The results indicated that the thermal decomposition of PRX is a two-stage process with the initial temperature of 198 °C either in nitrogen or air atmospheres. The thermal decompositions of the first stage in two atmospheres are the same process. The main part of the molecule, including sulfamide, amide, benzene ring and pyridine ring, decompose simultaneously and to form gasifiable small molecules and carbonaceous residue in the first stage. The second stage in nitrogen is a slow thermal pyrolysis process of carbonaceous residue. The forepart of the second stage in air is a slow thermal pyrolysis process as like as in nitrogen, and the later period of the second stage is an oxidation (combustion) reaction process of carbonaceous residue. PRX is stable under ambient temperature and air atmosphere, and it can be preserved for long-term storage under ambient temperature and in air atmosphere.

Study on the thermal decomposition of famciclovir

Abstract: The thermal decomposition of famciclovir (FCV) was measured with thermogravimetry, differential scanning calorimetry, and thermogravimetric analysis coupled with Fourier transform infrared spectroscopy. The IR spectra, high-performance liquid chromatography, and liquid chromatography–mass spectrometry of FCV and the residues of its thermal decomposition at various temperatures were determined. The molecular bond orders were calculated using an ab initio method from the GAMESS program of quantum chemistry. The mechanism of thermal decomposition for FCV was discussed. The kinetic parameters for thermal decomposition such as activation energy E a and the pre-exponential factor A were obtained using the Ozawa method. The prospective lifetime of FCV was estimated using the Dakin equation. The results indicated that the thermal decomposition of FCV is a two-step process. The initial decomposition temperature in either nitrogen or air is about 205 °C. The decomposition of FCV does not go through 2-amino-purine stage, 2-amino-purine, and alkane chain segment both decompose simultaneously during the first stage. For decomposition in nitrogen, the E a and A for the initial thermal decomposition are 107.8 kJ mol−1 and 2.19 × 109 min−1, respectively. For decomposition in air, the corresponding E a and A are 96.4 kJ mol−1 and 1.45 × 108 min−1, respectively. The FCV has good thermal stability under routine temperature.

Solid-State Characterization of Different Crystalline Forms of Sitagliptin

Abstract: Sitagliptin is an inhibitor of the enzyme dipeptidyl peptidase-4, used for the treatment of type 2 diabetes mellitus. The crystal structure of active pharmaceutical solids determines their physical and chemical properties. The polymorphism, solvates and hydrates can influence the free energy, thermodynamic parameters, solubility, solid-state stability, processability and dissolution rate, besides directly affecting the bioavailability. Thus, the physicochemical characterization of an active pharmaceutical ingredient is required to guarantee the rational development of new dosage forms. In this context, we describe herein the solid-state characterization of three crystalline forms of sitagliptin: sitagliptin phosphate monohydrate, sitagliptin phosphate anhydrous and sitagliptin base form. The investigation was carried out using differential scanning calorimetry (DSC), thermogravimetry (TG)/derivative thermogravimetry (DTG), spectroscopic techniques, X-ray powder diffraction (XRPD) and morphological analysis by scanning electron microscopy. The thermal analysis revealed that during the dehydration of sitagliptin phosphate monohydrate (Tpeak = 134.43 °C, ΔH = −1.15 J g−1) there is a characteristic crystalline transition event, which alters the physicochemical parameters of the drug, such as the melting point and solubility. The crystalline behavior of sitagliptin base form differs from that of sitagliptin phosphate monohydrate and sitagliptin phosphate anhydrous, mainly with regard to the lower temperature of the fusion event. The melting point (Tpeak) values obtained were 120.29 °C for sitagliptin base form, 206.37 °C for sitagliptin phosphate monohydrate and 214.92 °C for sitagliptin phosphate anhydrous. In relation to the thermal stability, sitagliptin phosphate monohydrate and sitagliptin phosphate anhydrous showed a slight difference; however, both are more thermostable than the base molecule. Therefore, through this study it was possible to establish the most suitable crystalline form of sitagliptin for the development of a safe, effective and appropriate pharmaceutical dosage form.

Formulation and characterization of lornoxicam-loaded cellulosic-microsponge gel for possible applications in arthritis.

Abstract: Rheumatoid arthritis (RA) is an autoimmune disease associated with severe joint pain Herein, we report lornoxicam loaded cellulosic microsponge gel formulation with sustained anti-inflammatory effects that are required to manage arthritic pain The microsponges were formulated using quasi emulsion-solvent diffusion method employing four different surfactant systems, namely polyvinyl alcohol (PVA), Tween80, Gelucire 48/16 and Gelucire 50/13 All the lornoxicam loaded microsponge formulations were extensively characterized with a variety of analytical tools The optimized microsponge formulation was then converted into gel formulation The lornoxicam loaded microsponge gel formulation had adequate viscosity and sufficient pharmaceutical properties as confirmed by the texture analysis and the drug release followed Super case II transport It is noteworthy that we described the preparation of a new cellulosic polymers based microsponge system for delivery of lornoxicam to provide quick as well as lasting (sustained) anti-inflammatory effects in rats using carrageenan induced rat paw edema model We were able to demonstrate a 72% reduction in inflammation within 4 h using the optimize transdermal gel formulation utilizing Transcutol P as permeation enhancer and with the aid of skin micro-piercing by microneedles, hence, demonstrating the potential of this microsponge gel formulation in arthritis management

Rheological and thermal degradation properties of hyperbranched polyisoprene prepared by anionic polymerization.

Abstract: Hyperbranched polyisoprene was prepared by anionic copolymerization under high vacuum condition. Size exclusion chromatography was used to characterize the molecular weight and branching nature of ...

Thermal Stability of Amorphous Solid Dispersions

Abstract: Amorphous solid dispersion drug delivery systems (ASD DDS) were proved to be efficient for the enhancement of solubility and bioavailability of poorly water-soluble drugs. One of the major keys for successful preparation of ASD is the selection of appropriate excipients, mostly polymers, which have a crucial role in improving drug solubility and its physical stability. Even though, excipients should be chemically inert, there is some evidence that polymers can affect the thermal stability of active pharmaceutical ingredients (API). The thermal stability of a drug is closely related to the shelf-life of pharmaceutical products and therefore it is a matter of high pharmaceutical relevance. An overview of thermal stability of amorphous solids is provided in this paper. Evaluation of thermal stability of amorphous solid dispersion is perceived from the physicochemical perspective, from a kinetic (motions) and thermodynamic (energy) point of view, focusing on activation energy and fragility, as well all other relevant parameters for ASD design, with a glance on computational kinetic analysis of solid-state decomposition.