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Abstract  

A number of disintegrants are available on the market. They improve tablets’ disintegration. The objective of this work is the comparison of the technological quality parameters of disintegrants using different analytical techniques. Three batches of disintegrants and their binary mixtures (water:disintegrants) were investigated. Cooling experiments were used from –30 up to 200C. The data obtained showed calorimetric differences between the samples. In the binary mixtures water showed different crystallization behaviour from the one found in the literature. According to the results DSC technique helped the quality control of different disintegrants.

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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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Abstract  

The standard molar enthalpy of formation of crystalline di-isobutyldithiocarbamate complexes of P, As, Sb and Bi(III) has been derived by solution calorimetry at 298.15 K. The corresponding standard molar enthalpies of sublimation were estimated by means of differential scanning calorimetry. From the standard molar enthalpies of formation of the gaseous chelates the homolytic and heterolytic mean metal-sulphur bond-dissociation enthalpies were calculated.

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Journal of Thermal Analysis and Calorimetry
Authors: Ana Santos, I. Basílio, F. de Souza, A. Medeiros, Márcia Pinto, D. de Santana, and R. Macêdo

Abstract  

Thermal analysis is an essential analytical tool in development of new formulations as well as to study the interaction between drugs and excipients. This work aims to investigate the possible interactions between metformin and excipients as microcrystalline cellulose (Microcel MC101®), starch sodium glycolate (Explosol®), sodium croscarmellose (Explosel®), PVP K30, magnesium stearate, starch and lactose, usually employed in pharmaceutical products. TG, DSC and DTA techniques were used for the thermal characterization to track if the thermal properties of the drug substance were modified in the mixture. Disregard of the starch and lactose systems, no changes in thermal behavior of mixtures were found. Thermogravimetric studies (TG) of metformin and its binary mixtures showed different thermal behavior.

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Abstract  

The present work reports studies of the thermal behaviour of some anti-hypertensive drugs. Their purities were determined by DSC and specialized pharmacopeial methods. The activation energy values suggest the following sequence of satability: nifedipine>propanolol hydrochloride>captoril. Analysis of the DSC data indicated that the degrees of purity of nifedipine, captopril and propanolol hydrochloride were similar to those found by pharmacopeial methods BP 93 and USP 23. The simplicity, speed and low operational costs of thermal analysis justify its application in the quality control of pharmaceutical drugs.

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Journal of Thermal Analysis and Calorimetry
Authors: R. Macêdo, J. Barbosa-Filho, E. da Costa, and A. de Souza

Abstract  

The terpenoids acetyl sitosterol, lupeol, acetyl diosgenin and stigmasterol were studied. Comparison of the thermogravimetric curves and the activation energies of the terpenoids suggested the following sequence of thermal stability: acetyl sitosterol < acetyl diosgenin < lupeol < stigmasterol. The DSC curves allowed determination of the melting points and the degrees of purity. Comparison of the TG and DSC curves revealed the presence of phase transitions without mass loss that were attributed to rearrangements in the terpenoid molecules.

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Journal of Thermal Analysis and Calorimetry
Authors: Rosali Ferreira da Silva, Flávia Morais de Medeiros, T. Nascimento, R. Macêdo, and P. Neto

Abstract  

The object of the present work is to study the thermal characteristics of indinavir sulfate and to evaluate the quality of the raw materials. Indinavir A, B, C and reference samples were obtained from different suppliers and submitted to TG, DSC and DSC-photovisual analyses. TG/DTG curves indicated a desolvation and dehydration processes and were confirmed by DSC. According to the DSC curves the fusion took place at about 141–142°C for indinavir C and Reference sample B and about 146–149°C for the others. DSC-photovisual showed insoluble raw materials for indinavir C at 160°C. Indinavir sulfate is highly hygroscopic drug which requires attention during storage and manufacture by pharmaceutical industry.

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Journal of Thermal Analysis and Calorimetry
Authors: Antonilêni Medeiros, Ana Santos, F. de Souza, J. Procópio, Márcia Pinto, and R. Macêdo

Abstract  

Stability of drugs and products has a great practical interest, which is facing to strict regulation. Thermal studies, besides the determination of the thermal properties of the investigated product allow the verification of possible interactions between the drug substances and excipients. The objective of this work was to obtain solid pre-formulates of paracetamol (PC) by spray drying (SPDR), as well as to investigate their thermal behavior. Dynamic and isotherm TG, conventional DSC and DSC-photovisual coupled methods were used to characterize the conventional and pre-formulated mixtures obtained by SPDR. The results of both DSC investigations showed slight alterations in melting temperatures, which suggests incompatibilities. The TG decomposition data of the mixtures evidenced that the dry process via SPDR leads to stability enhancement of the pre-formulated mixtures.

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Journal of Thermal Analysis and Calorimetry
Authors: Nadábia de Souza, F. de Souza, I. Basílio, Ana Medeiros, E. Oliveira, Ana Santos, R. Macwdo, and R. Macędo
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