Authors:Luciana Fernandes, W. Oliveira, J. Sztatisz, and Cs. Novák
Microencapsulation of Lippia sidoides essential oil was carried out by spray drying. Blends of maltodextrin and gum arabic were used as carrier. Spray dried microparticles
were characterized using conventional (thermogravimetry, evolved gas analysis) and combined (thermogravimetry-mass spectrometry
analysis) thermal analysis techniques in order to evaluate the abilities of carriers with different compositions in retaining
and in releasing the core vs. dynamic heating. Thermal analysis was useful to evaluate the physico-chemical interactions between
the core and carriers and to determine the protective effect of the carriers on the evaporation of essential oil.
Authors:Luciana Fernandes, W. Oliveira, J. Sztatisz, I. Szilágyi, and Cs. Novák
Inclusion complexes of Lippia sidoides essential oil and β-cyclodextrin were obtained by slurry method and its solid powdered form was prepared using spray drying.
The influence of the spray drying, as well as the different essential oil:β-cyclodextrin ratio on the characteristics of the
final product was investigated. With regard to the total oil retention 1:10 mass/mass ratio as optimal was found between the
essential oil and β-cyclodextrin.
Thermoanalytical techniques (TG, EGD, TG-MS) were used to support the formation of inclusion complex and to examine their
physicochemical properties after accelerated storage conditions. It may be assumed that the thermal properties of the complexes
were influenced not only by the different essential oil/ β-cyclodextrin ratio but also by the storage conditions. In the aspect
of their thermal stabilities, complex prepared with 1:10 m/m ratio (essential oil:β-cyclodextrin) was the most stable one.
Authors:M. I. Yoshida, M. A. Oliveira, E. C. L. Gomes, W. N. Mussel, W. V. Castro, and C. D. V. Soares
Thermogravimetry (TG) and differential scanning calorimetry (DSC) are useful techniques that have been successfully applied in the pharmaceutical industry to reveal important information regarding the physicochemical properties of drug and excipient molecules such as polymorphism, stability, purity, and formulation compatibility among others. In this study, lovastatin was studied by TG, DSC, and other techniques such as Fourier transform infrared spectroscopy, optical microscopy, X-ray diffraction, chromatography, and mass spectrometry. Lovastatin showed melting point at 445 K and thermal stability up to 535 K. It presented morphological polymorphism, which in the drug has the same unit cell, but with different crystal habits. Preservative excipient butylhydroxyanisole (BHA) causes amorphization of lovastatin crystallites and, therefore is incompatible with lovastatin. Degradation by hydrolysis was observed under neutral, acid, and basic conditions. The active degradation product, lovastatin hydroxyacid, was obtained after neutral and basic hydrolysis.
Authors:K. R. W. Oliveira, R. A. Sversut, A. K. Singh, M. S. Amaral, and N. M. Kassab
The present study aimed to develop and validate an analytical method for determination of marbofloxacin (MAR) in veterinary chewable tablets. The isocratic reversed-phase chromatographic method was developed and validated using a Vertisep®, RP C18 column (150 mm × 4.6 mm, 5.0 μm). The mobile phase was composed of water–acetonitrile (55:45, v/v) with pH adjusted to 3.0 with ortho-phosphoric acid and a flow rate set at 0.4 mL/min. The proposed method was validated for linearity in a concentration range of 2.5 to 17.5 μg/mL with a correlation coefficient of 0.99991. The mean content of MAR found in chewable tablets was 104.40% with RSD below 2%. The accuracy expressed as average recovery of the proposed method was 98.74%, and the precision expressed as relative standard deviation among repeated analysis was 0.55%. The method has adequate sensitivity with detection and quantitation limits of 0.25 and 0.81 μg/mL, respectively. Based on the presented results and according to the ICH and AOAC guidelines on validation of analytical methods, the proposed method was considered precise, accurate with adequate sensitivity, and robust in the MAR quantitative analysis. Therefore, the method can be used in the quality control of chewable veterinary tablets containing MAR.