scanning calorimetry (DSC) is a thermal analytical tool for preformulation
studies. Extrapolated melting temperature (TP)
and heat of fusion (ΔHf)
can be used as parameters for optimizing the DSC performance. Two model pharmaceuticals
acetaminophen and nicotinamide are used in this study. Using a factorial design
for the experimental model and matrix analysis the results, the effect of
sample mass, heating rate and the nitrogen flow rate were evaluated on the
and TP values. Two
levels for each of the procedural variables were used as a balanced experimental
design with two sample sizes, two heating rates and two nitrogen flow rates.
It was found that the change in the heating rate caused significant changes
in the ΔHf
values but not the Tp
values for acetaminophen. However, no significant effect was found for the Tp value but ΔHf value was affected to a
certain extent for nicotinamide.
Authors:M. Freitas, R. Alves, J. Matos, and J. Marchetti1
Osmotically controlled and oral drug delivery
systems utilize osmotic pressure for controlled delivery of active agent(s).
Drug delivery from these systems, to a large extent, is independent of the
physiological factors of the gastrointestinal tract and these systems can
be utilized for systemic as well as targeted delivery of drugs. We apply the
thermal methods and IR spectroscopy to study compatibility between atenolol
and several excipients usually found in the osmotic systems formulations (Polyethylene
oxide, MW 3350, 100000, 200000 and 5000000;
HPMC K4000, magnesium stearate and cellulose acetate.
acetate, HPMC K4000 and magnesium stearate have essentially no interaction
with atenolol otherwise all Polyethylene oxide excipients modifies significantly
the drug melting point indicating some extend of interaction.
Authors:M. Brown, E. Antunes, B. Glass, M. Lebete, and R. Walker
Differential scanning calorimetry was used to examine the thermal behaviour of mixtures of the drug prochlorperazine with
standard excipients, to assess potential interactions, and of mixtures with cyclodextrins, to investigate inclusion complexation
which could increase the photostability of the drug. For most of the excipients (magnesium stearate, stearic acid, Explotab®, Ac-Di-Sol®, Encompress® and Ludipress®, lactose and Starch 1500) disappearance or broadening of the melting endotherm of the drug indicated interactions. Lubritab® was the only 'inert' excipient tested. Mixtures of prochlorperazine and the cyclodextrins gave incomplete inclusion complexation
as shown by only partial disappearance of the melting endotherm of the drug.
Chemical compatibility of two drugs, namely, etamsylate and fluconazole was studied with lactose as excipient, employing differential
scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques. The DSC patterns recorded for the mixtures of both the
drugs with the common excipient (lactose) indicated that fluconazole as well as etamsylate were incompatible with lactose
at high temperatures. X-ray diffraction patterns recorded for pure drugs and lactose and the mixtures of individual drugs
with lactose prepared at room temperature by intimate grinding of the components revealed incompatibility of both the drugs
with lactose also at room temperature.
Authors:J. Van den Brande, Ilse Weuts, G. Verreck, J. Peeters, M. Brewster, and G. Van den Mooter
Thermal analysis was performed on the anti-HIV agent loviride in order to test its suitability to be processed using hot-melt
extrusion. Temperature characteristic parameters of crystallization were determined to quantify the stability of amorphous
loviride. The present study has shown that cooling and heating loviride at different rates influenced its thermal stability.
At high cooling rates melted loviride did not crystallize during cooling, and formed a glass that recrystallized during reheating.
Very low cooling rates resulted in significant decomposition of the drug. The glass transition temperature was found to increase
as a function of increasing heating rates and the activation energy for the transition from the glassy to the super-cooled
liquid state was relatively high, indicating good stability of the glass.
Authors:George G. G. de Oliveira, Humberto G. Ferraz, Patrícia Severino, and Eliana B. Souto
component of Active Antiretroviral Therapy (HAART) being typically the primary choice for efficient viral suppression [ 1 ]. Considering the risk of physicochemical changes of drugs during pre-formulation and handling, it is necessary to identify the