34 research outputs found
Effect of the granulometric characteristics of monensin sodium on controlling experimental coccidiosis in broiler chickens
Controlling Indomethacin Release through Vapor-Phase Deposited Hydrogel Films by Adjusting the Cross-linker Density
Ring Transformation of 1,4 (or 1,6)-Disubstituted 3,5-Dinitro-2-pyridones with Sodio β-Keto Esters
Effect of surface modification on hydration kinetics of carbamazepine anhydrate using isothermal microcalorimetry
The purpose of this research was to improve the stability of carbamazepine (CBZ) bulk powder under high humidity by surface modification. The surface-modified anhydrates of CBZ were obtained in a specially designed surface modification apparatus at 60°C via the adsorption of n-butanol, and powder x-ray diffraction, Fourier-Transformed Infrared spectra, and differential scanning calorimetry were used to determine the crystalline characteristics of the samples. The hydration process of intact and surface-modified CBZ anhydrate at 97% relative humidity (RH) and 40±1°C was automatically monitored by using isothermal microcalorimetry (IMC). The dissolution test for surface-modified samples (20 mg) was performed in 900 mL of distilled water at 37±0.5°C with stirring by a paddle at 100 rpm as in the Japanese Pharmacopoeia XIII. The heat flow profiles of hydration of intact and surface-modified CBZ anhydrates at 97% RH by using IMC profiles showed a maximum peak at around 10 hours and 45 hours after 0 and 10 hours of induction, respectively. The result indicated that hydration of CBZ anhydrate was completely inhibited at the initial stage by surface modification of n-butanol and thereafter transformed into dihydrate. The hydration of surface-modified samples followed a 2-dimensional phase boundary process with an induction period (IP). The IP of intact and surface-modified samples decreased with increase of the reaction temperature, and the hydration rate constant (k) increased with increase of the temperature. The crystal growth rate constants of nuclei of the intact sample were significantly larger than the surface-modified samples at each temperature. The activation energy (E) of nuclei formation and crystal growth process for hydration of surface-modified CBZ anhydrate were evaluated to be 20.1 and 32.5 kJ/mol, respectively, from Arrhenius plots, but the Es of intact anhydrate were 56.3 and 26.8 kJ/mol, respectively. The dissolution profiles showed that the surface-modified sample dissolved faster than the intact sample at the initial stage. The dissolution kinetics were analyzed based on the Hixon-Crowell equation, and the dissolution rate constants for intact and surface-modified anhydrates were found to be 0.0102±0.008 mg1/3 min−1 and 0.1442±0.0482 mg1/3·min−1. The surface-modified anhydrate powders were more stable than the nonmodified samples under high humidity and showed resistance against moisture. However, surface modification induced rapid dissolution in water compared to the control
New Effects in the Poly-N-Vinylcaprolactam/Titanium(IV) Oxides Nanocomposite System and Their Nature
Effects of Compression and Grinding on Chemical Stability of a Benzodiazepine Receptor Agonist
Stability and Stabilization Studies of TAK-599 (Ceftaroline Fosamil), a Novel N-Phosphono Type Prodrug of Anti-methicillin Resistant Staphylococcus aureus Cephalosporin T-91825
Predictive Approaches to Establishing, Understanding, and Communicating Risk with Emphasis on Early Development
Comparative evaluation of the degree of indomethacin crystallinity by chemoinfometrical fourie-transformed near-infrared spectroscopy and conventional powder X-ray diffractiometry
A chemoinfometrical method for evaluating the degree of crystallinity based on fourie-transformed near-infrared (FT-NIR) spectroscopy was established and compared with the conventional powder X-ray diffraction method. Powder X-ray diffraction profiles and FT-NIR spectra were recorded for 11 kinds of standard materials with various degrees of crystallinity obtained by physically mixing crystalline and amorphous indomethacin (IMC). Chemoinfometric analysis was performed on the FT-NIR spectral data sets by multiple linear regression (MLR) (MLR-Set-Up Search program). The crystalline and amorphous forms showed significant NIR spectral peaks. MLR analysis was performed based on normalized NIR spectra sets for standard samples of known crystallinity. A calibration equation was determined to minimize the root mean square error of prediction. The predicted crystallinity values were reproducible and had a smaller standard deviation. The values of crystallinity predicted by X-ray powder diffractometry and FT-NIR spectrometry suggested a satisfactory correlation between the 2 techniques. The results indicated that FT-NIR spectroscopy provides for an accurate quantitative analysis of crystallinity compared with conventional X-ray diffractometry