The Experts below are selected from a list of 5049 Experts worldwide ranked by ideXlab platform
Helen A Archontaki - One of the best experts on this subject based on the ideXlab platform.
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kinetic study on the degradation of indomethacin in alkaline aqueous solutions by derivative ultraviolet spectrophotometry
Analyst, 1995Co-Authors: Helen A ArchontakiAbstract:A fourth-order derivative method for monitoring a degradation product is proposed for the kinetic investigation of the alkaline hydrolysis of indomethacin, where indomethacin co-exists with its degradation products. A second-order derivative approach for monitoring the parent compound itself was also examined but showed limitations. Detection limits for the second-and fourth-order derivative methods, defined as b+ 3sb, are 4 × 10–6 and 2 × 10–6 mol dm–3, respectively. In this work the kinetic investigation of the alkaline hydrolysis of indomethacin was carried out at pH levels of 8.0, 9.0 and 10.0. Two sets of recovery studies, in order to calculate one substance in the presence of the other, gave us 104.0 ± 0.3% and 96.8 ± 9.7%(for the second-order derivatization) and 100.9 ± 0.9% and 101.4 ± 1.5%(for the fourth-order derivative approach) showing that only the latter method can be considered free of interference and is analytically useful. Accelerated studies at higher temperatures have been employed that enable rapid prediction of the long-term stability of this Drug at pH 8.0 (90 °C), 9.0 (35, 40 and 45 °C) and 10.0 (20, 26 and 30 °C). At pH 9.0 and 10.0 enough data were produced to draw Arrhenius plots and calculate the activation energies for Drug Decomposition: Ea= 17 ± 1 kcal mol–1(1 cal = 4.184 J) and 14 ± 1 kcal mol–1, respectively. Kinetic results for kobs and t1/2 at room temperature (25 °C) were estimated from the Arrhenius plots: kobs= 7.7 × 10–4 min–1 and t1/2= 900 min at pH 9.0 and kobs= 7.3 × 10–3 min–1 and t1/2= 95 min at pH 10.0. Measurements of absorbance at a wavelength of 360 nm in the zero-order spectrum of indomethacin were included in our study for the purpose of comparison, as well as literature results.
Túlio Flávio Accioly De Lima E Moura - One of the best experts on this subject based on the ideXlab platform.
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application of thermal analysis to the study of antituberculosis Drugs excipient compatibility
Journal of Thermal Analysis and Calorimetry, 2014Co-Authors: Edilene P. Lavor, Marco V. M. Navarro, Fátima Duarte Freire, Cícero Flávio Soares Aragão, Fernanda Nervo Raffin, Euzébio Guimarães Barbosa, Túlio Flávio Accioly De Lima E MouraAbstract:First-line Drugs (rifampicin, RIF; isoniazid, INH; ethambutol, ETA; and pyrazinamide, PZA) recommended in conventional treatment of tuberculosis were analyzed in 1:1 w/w binary mixtures with microcrystalline cellulose MC 101 (CEL) and lactose supertab® (LAC) by differential scanning calorimetry (DSC), thermogravimetry (TG), differential thermal analysis (DTA), and Fourier transformed infrared analysis (FTIR) as part of development of fixed dose combination (FDC) tablets. Evidence of interaction between Drug and pharmaceutical excipients was supposed when peaks disappearance or shifting were observed on DTA and DSC curves, as well as decreasing of Decomposition temperature onset and TG profiles, comparing to pure species data submitted to the same conditions. LAC was showed to interact with RIF (absence of Drug fusion and recrystallization events on DSC/DTA curves); INH (thermal events of the mixtures different from those observed for Drug and excipient pure in DSC/DTA curves); PZA (decrease on Drug fusion peak in DSC/DTA curves), and ETA (shift on Drug onset fusion and absence of pure LAC events on DSC/DTA curves). In all cases, an important decrease on the temperature of Drug Decomposition was verified for the mixtures (TG analysis). However, FTIR analysis showed good correlation between theoretical and experimental Drug-LAC spectra except for INH–LAC mixture, evidencing high incompatibility between these two species and suggesting that those interactions with PZA and RIF were thermally induced. No evidence of incompatibilities in CEL mixtures was observed to any of the four-studied Drugs.
Marcilio Cunhafilho - One of the best experts on this subject based on the ideXlab platform.
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preformulation studies of itraconazole associated with benznidazole and pharmaceutical excipients
Thermochimica Acta, 2014Co-Authors: I Alvessilva, Livia Lira Sabarreto, Eliana Martins Lima, Marcilio CunhafilhoAbstract:Abstract Recent studies have shown that the antifungal itraconazole (ITZ), when in associations with benznidazole (BNZ), is a potential treatment for Chagas disease. Therefore, the objective of the present study was to evaluate the compatibility of ITZ with BNZ and with selected pharmaceutical excipients. Differential scanning calorimetry (DSC), derivative thermogravimetry (DTG), Fourier transform infrared spectroscopy (FTIR), optical microscopy and kinetic analyses under isothermal conditions were performed. The results showed thermal interactions between ITZ and the excipients hydroxypropyl methylcellulose and polyvinylpyrrolidone. The FTIR data together with complementary tests revealed signs of Drug Decomposition in the presence of these materials. Thus, these excipients were considered incompatible with ITZ and should be avoided in solid dosage forms containing this Drug. Moreover, it was found that associations between ITZ and BNZ are potentially unstable. Therefore, it is necessary to develop a pharmaceutical dosage form that avoids the processing of these Drugs together and allows a stable pharmaceutical formulation to be obtained.
J T Carstensen - One of the best experts on this subject based on the ideXlab platform.
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the state of water in Drug Decomposition in the moist solid state description and modelling
International Journal of Pharmaceutics, 1992Co-Authors: J T CarstensenAbstract:Abstract The state of moisture as it is involved in Decomposition of Drugs in a moist solid state is classified and described. Equations useful for describing such Decomposition are discussed in the light of reported experimental data.
Edilene P. Lavor - One of the best experts on this subject based on the ideXlab platform.
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application of thermal analysis to the study of antituberculosis Drugs excipient compatibility
Journal of Thermal Analysis and Calorimetry, 2014Co-Authors: Edilene P. Lavor, Marco V. M. Navarro, Fátima Duarte Freire, Cícero Flávio Soares Aragão, Fernanda Nervo Raffin, Euzébio Guimarães Barbosa, Túlio Flávio Accioly De Lima E MouraAbstract:First-line Drugs (rifampicin, RIF; isoniazid, INH; ethambutol, ETA; and pyrazinamide, PZA) recommended in conventional treatment of tuberculosis were analyzed in 1:1 w/w binary mixtures with microcrystalline cellulose MC 101 (CEL) and lactose supertab® (LAC) by differential scanning calorimetry (DSC), thermogravimetry (TG), differential thermal analysis (DTA), and Fourier transformed infrared analysis (FTIR) as part of development of fixed dose combination (FDC) tablets. Evidence of interaction between Drug and pharmaceutical excipients was supposed when peaks disappearance or shifting were observed on DTA and DSC curves, as well as decreasing of Decomposition temperature onset and TG profiles, comparing to pure species data submitted to the same conditions. LAC was showed to interact with RIF (absence of Drug fusion and recrystallization events on DSC/DTA curves); INH (thermal events of the mixtures different from those observed for Drug and excipient pure in DSC/DTA curves); PZA (decrease on Drug fusion peak in DSC/DTA curves), and ETA (shift on Drug onset fusion and absence of pure LAC events on DSC/DTA curves). In all cases, an important decrease on the temperature of Drug Decomposition was verified for the mixtures (TG analysis). However, FTIR analysis showed good correlation between theoretical and experimental Drug-LAC spectra except for INH–LAC mixture, evidencing high incompatibility between these two species and suggesting that those interactions with PZA and RIF were thermally induced. No evidence of incompatibilities in CEL mixtures was observed to any of the four-studied Drugs.
