AIMTo study the thermal stability, decomposition process and kinetics of such purine pharmaceuticals as aciclovir (Acv), penciclovir (Pcv), and their parent substance, guanine.

METHODSUsing infrared technique, accelerating test method and thermogravimetry to investigate the thermal decomposition processes and using Coast-Redfern method, MKN method and Ozawa method to deal with the data to get kinetic functions.

RESULTSThe decomposition process and the formed products were derived, the kinetic model function was suggested by comparison of the kinetic parameters.

CONCLUSIONPcv and Acv's degrading product for the first step is guanine. The sequences of their thermal stabilities is: Pcv > Acv. The two drugs' kinetic equation of thermal decomposition is expressed as: da/dt = Ae-Ea/RT2(1-alpha)3/2.

Acyclovir ; analogs & derivatives ; chemistry ; Drug Stability ; Guanine ; chemistry ; Hot Temperature ; Kinetics ; Thermodynamics ; Thermogravimetry

5R-5-hydroxytriptolide (LLDT-8) is a new drug candidate which is in clinical trial treating rheumatoid arthritis. Polymorph screening of the compound was carried out in this study. Polymorph of LLDT-8 was prepared by evaporative crystallization and antisolvent crystallization methods and was characterized by powder X-ray diffraction (p-XRD), infrared spectrometry (IR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TG). It was found that p-XRD patterns, DSC curves, TG curves and IR spectra of the LLDT-8 samples prepared by the above recrystallization methods were all consistent. The 20 of main peaks in the p-XRD patterns appeared at 7.58 degrees, 8.14 degrees, 8.66 degrees, 15.46 degrees, 16.46 degrees, 29.54 degrees, 31.16 degrees and 38.26 degrees, while the infrared absorption peaks appeared at 3 471.3, 2 962.2, 2 887.0, 1 762.6, 1 677.8, 1 432.9, 1 365.4, 1 247.7, 1 080.0, 1 031.7 and 877.5 cm(-1). LLDT-8 was decomposed at 271.2 degrees C based on the determination from DSC and TG. It was showed in single crystal X-ray diffraction study that LLDT-8 crystal was monoclinic with the space group being P2 (1). The cell parameters were found to be: a = 11.460 1 (11), b = 6.320 5 (6), c = 13.028 1 (12), alpha = 90.00, beta = 115.557 (2) and gamma = 90.00. The crystal was a hydrogen-bonded dimmer. The slurry experiments, which were further conducted in solvents with different polarities, confirmed the stability of solid state of LLDT-8 based on the p-XRD determination. The polymorph of LLDT-8 made assurance of its efficacy consistence during its clinical trials.
Calorimetry, Differential Scanning ; Crystallization ; Diterpenes ; chemistry ; Drug Stability ; Spectrophotometry, Infrared ; Thermogravimetry ; X-Ray Diffraction

OBJECTIVETo investigate the processing mechanism of Zushima which was stir-fried with licorice.

METHODStudy of pyrolysis characteristics for extraction of Zushima effective part, petroleum ether, chloroform, ethyl acetate, n-butanol parts and the mixture of Zushima effective parts and licorice solid powder according to the proportion of 10: 1, 10: 2, 10: 3 was carried out in the thermogravimetric analyzer, the simulation of air (N2-O2 4:1) was chosen as carrier gas and heating rate was 5 degrees C x min(-1).

RESULTCompared with TG-DTG curve of Zushima effective parts, the major weightloss temperature range of petroleum ether extraction which has strong stimulation was 320-390 degrees C, 0.69% x min(-1) weightlessness rate peak gradually moved forward with the addition of licorice powder, finally it was merged with the peak around 265 degrees C. In addition, effective department of Zushima at 291, 516 degrees C for 2.38% x min(-1) and 2.42% x min(-1) thermal weightlessness rate peak shift to lower temperature, the moving range were about 20-26, 19-50 degrees C, the former was significantly reduced, the latter was significantly increased.

CONCLUSIONIn the course of programmed temperature heating, petroleum ether department was easy to lose with the addition oflicorice solid powder. At the same time, the main efficacy components of Zushima had a slow loss rate, which supported the processing mechanisms of TG-DTG method to research traditional Chinese medicine, and verified irritating characteristics that stimulus reduced after stir-fried with licorice.

Chemistry, Pharmaceutical ; methods ; Drugs, Chinese Herbal ; chemistry ; isolation & purification ; Glycyrrhiza ; chemistry ; Thermogravimetry ; methods

This article studies the thermostability and the crystal structure of a new anticancer drug dasatinib. The thermostability of dasatinib was analyzed using the differential scanning calorimeter (DSC) and thermo gravimetric analyzer (TGA), and the structural characteristics of polymorphism and crystalline transformation was determined using the X-ray powder diffractometry (XRD) with in-situ high temperature accessories. The results showed that dasatinib has at least two different crystal forms. The form-I has one crystalline water and form-II one and half, and in a heating-up processing both of them would change their crystal structures. After losing their crystalline water, both would change into the same crystalline form with no crystalline water. Their melting points were almost the same: form-I was 285.68 degrees C and form-II was 285.50 degrees C. The results of the study method would provide a comprehensive reference for the quality evaluation of dasatinib.
Antineoplastic Agents ; chemistry ; Calorimetry, Differential Scanning ; Crystallization ; Dasatinib ; Molecular Structure ; Protein Kinase Inhibitors ; chemistry ; Pyrimidines ; chemistry ; Temperature ; Thermogravimetry ; Thiazoles ; chemistry ; X-Ray Diffraction

The aim of the study was to evaluate the effect of adding acrylamide monomer (AAm) on the characterization, flexural strength, flexural modulus and thermal degradation temperature of poly(methyl methacrylate) (PMMA) denture-base resins. Specimens (n=10) were fabricated from a conventional heat-activated QC-20 (Qc-) and a microwave heat-activated Acron MC (Ac-) PMMA resins. Powder/liquid ratio followed the manufacturer's instructions for the control groups (Qc-c and Ac-c) and for the copolymer groups, the resins were prepared with 5% (-5), 10% (-10), 15% (-15) and 20% (-20) acrylamide contents, according to the molecular weight ratio, respectively. The flexural strength and flexural modulus were measured by a three-point bending test. The data obtained were statistically analyzed by Kruskal-Wallis test (α=0.05) to determine significant differences between the groups. The chemical structures of the resins were characterized by the nuclear magnetic resonance spectroscopy. Thermal stabilities were determined by thermogravimetric analysis (TGA) with a heating rate of 10 °C⋅min(-1) from 35 °C to 600 °C. Control groups from both acrylic resins showed the lowest flexural strength values. Qc-15 showed significant increase in the flexural strength when compared to Qc-c (P<0.01). Ac-10 and Ac-15 showed significance when compared to Ac-c (P<0.01). Acrylamide incorporation increased the elastic modulus in Qc-10, Qc-15 and Qc-20 when compared to Qc-c (P<0.01). Also significant increase was observed in Ac-10, Ac-15 and Ac-20 copolymer groups when compared to Ac-c (P<0.01). According to the (1)H-nuclear magnetic resonance (NMR) results, acrylamide copolymerization was confirmed in the experimental groups. TGA results showed that the thermal stability of PMMA is increased by the insertion of AAm.
Acrylamide ; chemistry ; Acrylic Resins ; chemistry ; Dental Materials ; chemistry ; Denture Bases ; Elastic Modulus ; Hot Temperature ; Humans ; Magnetic Resonance Spectroscopy ; Materials Testing ; Microwaves ; Pliability ; Polymerization ; Polymethyl Methacrylate ; chemistry ; Powders ; Solutions ; Stress, Mechanical ; Thermodynamics ; Thermogravimetry ; Time Factors

The drug-loading system of DMF (dextran - magnetic layered double hydroxide - fluorouracil) was synthesized by "co-precipitation intercalated assembly - dextran composite in situ - solvent conversion" technology. The crystal-phase characteristic and slow-release performance of DMF were investigated through X-ray diffraction (XRD), infrared spectrum (IR), transmission electron microscopy (TEM), thermogravimetry (TG) and in vitro release experiment. The targeted transshipment and slow-release effect of DMF system were evaluated by in vivo animal experiment. It was showed that the XRD of DMF matched with R-sixtetragonum type layered double hydroxide and Fd-3m cubic type ferrite. IR test demonstrated that the DMF system was a supra-molecular complex consisted of Dextran (DET), magnetic layered double hydroxide (MLDH) and fluorouracil (FU) components. The two-level supra-molecular MLDH-FU presented six-edge lozenge TEM morphology, with layered characteristics. DET on the surface of DMF was capable of protecting the layered structure of MLDH-FU, improving particle dispersion properties, and strengthening the slow-release performance of the drug delivery system. The drug release model of DMF at pH 7.35 of PBS in vitro fit to the zero-order kinetics equation C = 1.1716 x 10(-5) + 4.4626 x 10(-7) t. The drug delivery system DMF could transport drugs principally to in vivo target organs with a local effect, targeted specificity, and excellent circulation transshipment performance. The pharmacokinetic process of DMF presented multi-peak phenomenon with peak attenuation and cyclic growth. The peaks appeared at 0.25, 1, 3, 5 and 9 d separately after dosing intervention. The first peak process of DMF accorded with a pharmacokinetic equation of C(FU) = 14.34 e(-0.530t) + 36.04 e(-0.321t) + 24.18 e(-0.96t), and presented the characteristic of slow absorption and fast elimination. As for subsequent peak processes, half-life increased, bioavailability increased, and plasma clearance decreased. The highest peak value of DMF was 1/37 of original value of FU, and the relative bioavailability was 419% to original FU.
Animals ; Biological Availability ; Delayed-Action Preparations ; Dextrans ; chemistry ; Drug Carriers ; Female ; Fluorouracil ; administration & dosage ; chemistry ; pharmacokinetics ; Half-Life ; Hydroxides ; chemistry ; Magnetics ; Male ; Microscopy, Electron, Transmission ; Rats ; Rats, Sprague-Dawley ; Spectrophotometry, Infrared ; Thermogravimetry ; X-Ray Diffraction

OBJECTIVETo study processing method and mechanism of Calamine.

METHODThermogravimetry analysis method and nano-technology were adopted to analyze and synthesize the components in Calamine, Tetracycline was took as the comparison drug to determine the antibacterial activity of Calamine and its components.

RESULTA part of zinc carbonate in Calamine was decomposed into zinc oxide when processing, and the particle size was smaller than before. The antibacterial activity of Calamine is decided by the content and particle size of zinc oxide, and has nothing with zinc carbonate. The more content and the smaller particle size of zinc oxide, the more powerful antibacterial activity of Calamine.

CONCLUSIONThe content and the particle size of zinc oxide can be the important targets in the processing of Calamine.

Anti-Bacterial Agents ; pharmacology ; Carbonates ; chemistry ; pharmacology ; Drug Combinations ; Escherichia coli ; drug effects ; Ferric Compounds ; chemistry ; pharmacology ; Materia Medica ; chemistry ; pharmacology ; Nanostructures ; Nanotechnology ; Particle Size ; Pseudomonas aeruginosa ; drug effects ; Salmonella ; drug effects ; Staphylococcus aureus ; drug effects ; Technology, Pharmaceutical ; methods ; Tetracycline ; pharmacology ; Thermogravimetry ; Zinc Compounds ; chemistry ; pharmacology ; Zinc Oxide ; analysis ; chemistry ; pharmacology