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Journal of Thermal Analysis and Calorimetry
Authors: M. Łaszcz, K. Trzcińska, K. Filip, A. Szyprowska, M. Mucha, and P. Krzeczyński

samples of capecitabine: KP-1 and KP-2, produced at the Pharmaceutical Research Institute in Warsaw and the commercial one KP-API2 (Aurisco Pharmaceutical Limited Batch No. 081105) were taken into the stability studies. Capecitabine was stored at following

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Abstract  

A new formulation of nifedipine tablets was prepared. The tablets were conditioned in amber-colored glass containers and placed in a climatized room at 40 °C and relative humidity of 75% for 180 days. Differential scanning calorimetry (DSC) and Thermogravimetry (TG) were used in order to evaluate the thermal properties of nifedipine, the excipients and two well-known nifedipine degradation products. There is no evidence of interaction between nifedipine and excipients or degradation products. High performance liquid chromatography (HPLC) was used in the dosage of nifedipine tablets before and after acclimatized exposure. Results show that DSC and TG offer important data for a more detailed assessment of the stability of a pharmaceutical formulation.

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A robust and eco-friendly stability-indicating high-performance thin-layer chromatography (HPTLC) method was developed for the stability study of thiocolchicoside using analytical quality-by-design approach. Full factorial design was used for screening potential variables affecting method development. Box‒Behnken design was used subsequently for investigation of the main, interactive, and quadratic effects of these variables on response. Four potential variables were selected on the basis of scientific knowledge for the development of a method for the stability study of thiocolchicoside. The selected potential factors, namely, volume of water (mL), saturation time (min), migration distance (mm), and volume of mobile phase (mL) were screened by 24 full factorial designs by selecting resolution as a critical method attribute. Pareto chart analysis showed that 3 variables, namely, volume of water (mL), saturation time (mm), and migration distance (mm), out of 4 potential variables were significantly affecting the response variable (resolution). Optimization with response surface methodology further clarified the relationship between critical variables and resolution using Box–Behnken design. The experimental design model was found to be quadratic, and the design space was developed on the basis of suggested model for optimization of critical method variables for maximum desirable resolution and for the development of a control strategy of the HPTLC method for the stability study of thiocolchicoside. The developed method was validated for linearity, range, specificity, precision, accuracy, limit of detection and limit of quantification as per the International Conference on Harmonization guidelines (ICH) Q2 (R1). The developed method was applied for the estimation of thiocolchicoside in its pharmaceutical dosage forms. The degradation products formed in acidic and alkaline media were isolated and characterized by their infrared (IR), nuclear magnetic resonance (NMR), and mass spectral data.

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Abstract  

This study demonstrates the thermalanalysis applications in compatibility and stability studies of the propranolol binary mixture sand tablets A and B. The propranolol binary mixtures were prepared in the laboratory and compared to the fully formulated tablets using the thermogravimetric (TG) and calorimetric(DSC) methods. DSC of binary mixtures showed similar phase transition to propranolol drug. The tablets phase transition decreased and there was no detectable significant interaction in propranolol–lactose mixture and tablets. The DSC-photovisual test revealed an interaction similar to the Maillard reaction. The TG isothermal study showed a difference in the profile between the drug and tablets due excipients quality and problems in manufacture process. The kinetic parameters indicated a lower stability for the tablets than propranolol drug. The thermal techniques thermally differentiated the propranolol preparations demonstrating the importance in the design development of pharmaceuticals solid-dosage form.

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Incidence of suicidal attempts presents an explanation for the high prevalence of quetiapine (QTI) in forensic cases. Thus, the interpretation of its concentrations in biological specimens is needed, but in forensic toxicology, potential postmortem changes such as instability of the target drugs should be taken in consideration. High-performance liquid chromatography (HPLC) method has been developed for determination of QTI. This method was based on reversed phase (RP)-HPLC separation of QTI on a C-18 column (150 mm × 4.6 mm, 5 μm) with elution system of acetonitrile—methanol—0.025 M phosphate buffer (pH 2.5), containing 1 mL TEA in each 250 mL, in a ratio of 40:30:30%, v/v, at the flow rate of 1.2 mL min−1 using mirtazapine as internal standard (IS). The proposed method was applied to the determination of QTI in plasma in presence of coadministered drugs. The application of the proposed method was extended for long-term stability study of two different concentration levels of QTI in the whole blood.

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Thermal stability study of the protease inhibitors

Nelfinavir mesylate and atazanavir sulfate

Journal of Thermal Analysis and Calorimetry
Authors: Katarzyna Michalik, Zofia Drzazga, Anna Michnik, and M. Kaszuba

Abstract  

A thermal and kinetic analysis of two protease inhibitors: nelfinavir mesylate and atazanavir sulfate, were carried out to find their thermal stability. DSC curves of both drugs showed exothermic transition. This observed process resulted in two steps. Obtained apparent activation energy pointed at low stability of studied protease inhibitors in water solutions.

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Abstract  

Thermogravimetry technique is useful to determine the thermal stability of vegetable oils. In this paper some vegetable oils obtained from brazilian Cerrado native plants were studied based on their high oleic acid content. Amburana, baru and pequi pulp oils presented higher yield of extraction compared to soybean oil. The thermal stability of oils in nitrogen was very close hence their fatty acid composition was very similar. Amburana and baru oils have major amount of unsaturated fatty acids, especially linoleic acid and pequi pulp oil has the highest short chain fatty acid content which can explain its lowest thermal stability in synthetic air.

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Two stability-indicating chromatographic methods were developed for the analysis of dapsone in presence of its oxidative degradants. Forced degradation studies were performed on the drug substance using 30% hydrogen peroxide. The degradation products were identified by infrared spectroscopy and mass spectrometry, and a pathway is illustrated. The first method was based on thin-layer chromatographic separation of the drug from its oxidative degradants, followed by densitometric measurement of the intact drug spot at 289 nm. The developing system used for separation is ethyl acetate-toluene in the ratio 1:1 (v/v). The linear range was 0.5–6.0 μg/spot, with mean recoveries of 99.37 ± 0.96%. The second method was based on reversed-phase liquid chromatographic separation of the drug from its oxidative degradants on a C18 column, using the mobile phase methanol-water (65:35, v/v) at the controlled temperature of 25°C. Quantification was achieved by UV detection at 289 nm, based on peak area. The linear range was 5–65 μg mL−1 with mean recoveries 99.50 ± 1.70%. The methods were validated according to guidelines of International Conference on Harmonization. The HPLC method was used to investigate the kinetics of oxidative degradants at different temperatures.

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Abstract  

A formulation of nifedipine tablets was prepared in the present research. The tablets were conditioned in amber-colored glass containers and placed in a climatized room at 40°C and relative humidity of 75% for 180 days. Differential scanning calorimetry (DSC) and thermogravimetry (TG) were used in order to evaluate the thermal properties of nifedipine, the excipients and two well-known nifedipine degradation products. The results demonstrated that there is no evidence on the interaction between nifedipine and excipients, or degradation products.

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Journal of Thermal Analysis and Calorimetry
Authors: M. R. S. Silva, S. C. Souza, I. M. G. Santos, M. R. Cassia-Santos, L. E. B. Soledade, A. G. Souza, S. J. G. Lima, and E. Longo
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