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.
Authors:R. Macêdo, O. de Moura, A. de Souza, and A. Macêdo
This work present comparative results on powder milk storage quality, obtained from analytical methods. Protein content was
determined conventional (Kjeldahl) and colorimetric with biuret reagent at 540 nm and integral quality by thermogravimetric
and biological methods. A method was developed for the protein separation of powder milk. Powder milk was submitted to degradation
processes at 45, 60 and 80°C for 20 days. The results indicated that protein content values were inconsistent if determinations
by Kjeldahl and colorimetric methods and biological tests were compared. There is evidence of thermal decomposition of powder
milk as detected by biological and thermogravimetric methods.
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.
This work proposes thermal characterization as analytical methodology for the identification and purity assay of warifteine,
an alkaloid in Cissampelos sympodialis Eichl. Thermal and kinetic parameters were determined by means of TG and DSC photovisual studies. The TG results showed that
the decomposition of warifteine in air and nitrogen atmospheres proceeds in three and four steps, respectively. The TG data
allowed calculation of the kinetic parameters of warifteine. The activation energy values obtained by different methods displayed
a good correlation. With the DSC photovisual system applied it is possible to detect the impurity level in warifteine after
Authors:R. Macêdo, T. Gomes do Nascimento, and J. Veras
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
Authors:Ana Medeiros, Lidiane Correia, Mônica Simões, and R. Macêdo
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
Authors:F. Santos de Souza, A. Gomes Barreto, and R. Macêdo
The present work proposes evaluation of the gelatinization processes of starch by means of DSC coupled with a photovisual
system. The use of DSC, TG and DTA for a fast and efficient evaluation of the starch is suggested. The DSC curves of starch
gels with water contents of 20, 30, 40 and 50% (mass/v) exhibited different phase transitions, corresponding to the gelatinization
processes at the different water contents for the different lots. The DSC-photovisual system confirmed calorimetric behaviour
differences between the starch lots studied.
Authors:A. de Medeiros, N. de Cervantes, A. Gomes, and R. Macêdo
TG and DSC data were used to determine the thermal parameters of prednisone drug and tablets. Two formulations of prednisone
20 mg were analysed in the form of tablets. The TG curves of prednisone drug and tablets A and B displayed six, eight and
seven thermal decomposition processes, respectively. Analysis of the DSC data pointed to chemical interactions between prednisone
drug and the excipients of tablets A and B, suggested by alterations in the melting temperature of prednisone. The analysis
revealed that prednisone drug is more stable than tablets A and B.