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Abstract  

Thermal characterization is proposed as analytical methodology for the purity assay of lapachol, and for determination of the quality parameters of capsules containing this molecule. The TG data revealed that lapachol is more stable in the presence of adjuvants, showing the good quality of the formulation. The kinetic parameters obtained were lower for lapachol drug than for the formulated lapachol. The DSC data demonstrated good compatibility between lapachol drug and the adjuvant in the formulated lapachol, and did not reveal impurities such as secondary products of the isolation and recrystallization processes. The data were confirmed by the DSC-photovisual findings.

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Abstract  

The compatibilities and stabilities of some binary mixtures and generic hydrochlorothiazide formulations were studied by using TG, DSC and a DSC-photovisual system. The kinetic parameters were determined via the Arrhenius equations. Tablet B presented higher compatibility and thermal stability than those of tablets A and C. The photovisual system demonstrated that the decomposition of tablet A occurs before the melting point, due to the Maillard reaction between the hydrochlorothiazide and lactose present in the formulation. The behaviour and rate constants of binary mixtures suggest that lactose can be substituted for microcrystalline cellulose, MC(101), in tablet A. The DSC and TG data revealed different characteristics of compatibility and stability in generic formulations from different manufacturers.

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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 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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