Thermal Decomposition Kinetics of Ursodeoxycholic Acid Drug Crystal

Abstract

The crystallization of ursodeoxycholic acid drug crystals in gel by reduction of solubility method is the first of its kind to be reported in literature. Monoclinic crystalline form of the structure was confirmed using single crystal X-ray diffraction analysis. This report deals with the kinetic analysis made from the thermogravimetric analysis/differential thermal analysis (TGA/DTA) data using Coats-Redfern (CR) relation. Thermodynamic parameters were also determined. Arrhenius equation for ursodeoxycholic acid was derived as k = 3.10 × 10 .

Determination of Mefenamic Acid in a Topical Emulgel by a Validated HPLC Method

“…3E). The results were consistent with previous studies that mefenamic acid was susceptible to high temperature and thermal decomposition was nonspontaneous with Gibbs free energy (∆G) of 131.01 kJ/mol [24]. These results presented that the proposed method was selective and could separate mefenamic acid from the other chemicals and degradation products.…”

A New Technique for Calculating Kinetic and Thermodynamic Barriers for Nucleation Rates and Interfacial Energy of CaCO3 Prenucleation Nanoclusters at High Temperature Using TGA Models and In Situ Crystallization

“…[ 63 ] Different studies have suggested a tenfold variation in the nucleation rates due to assumption of constant $${J}_o$$ values at normal temperature points. [ 12–64 ] Consequently, computation of $${J}_o$$ was performed by determining $${A}_{\alpha}\ \mathrm{and}\ {E}_{\alpha}$$, using experimentally generated TGA data. A precise value of apparent activation energy $$( {{E}_\alpha } )$$ of nucleation for CCPN matrix is computed by iterative procedure (Equation (16)) and provided in Table 2 and Table S2 (Supporting Information).…”

“…The following Equations [ 42 ] are presented to calculate thermodynamic parameters $$( {\Delta H,\ \Delta G\ {\rm and}\ \Delta S} )$$, Where $$\Delta H$$, $$\Delta G$$ and $$\Delta S$$ correspond to change in enthalpy ($$\Delta H$$), change in Gibbs free energy ($$\Delta G$$), and change in entropy ($$\Delta S$$), respectively. $$$$\begin{equation}\Delta H = {E}_\alpha - RT \end{equation}$$$$ $$$$\begin{equation} \Delta G={E}_{\alpha}+R{T}_{p}\textit{ln}\left(\frac{{k}_{B}{T}_{p}}{\textit{hA}}\right) \end{equation}$$$$ $$$$\begin{equation}\Delta S = \frac{{\Delta H - \Delta G}}{{{T}_p}} \end{equation}$$$$Here, $${k}_{B}$$ is Boltzmann constant (…”