New Lidocaine-Based Pharmaceutical Cocrystals: Preparation, Characterization, and Influence of the Racemic vs. Enantiopure Coformer on the Physico-Chemical Properties

This study describes the preparation, characterization, and influence of the enantiopure vs. racemic coformer on the physico-chemical properties of a pharmaceutical cocrystal. For that purpose, two new 1:1 cocrystals, namely lidocaine:dl-menthol and lidocaine:d-menthol, were prepared. The menthol racemate-based cocrystal was evaluated by means of X-ray diffraction, infrared spectroscopy, Raman, thermal analysis, and solubility experiments. The results were exhaustively compared with the first menthol-based pharmaceutical cocrystal, i.e., lidocaine:l-menthol, discovered in our group 12 years ago. Furthermore, the stable lidocaine/dl-menthol phase diagram has been screened, thoroughly evaluated, and compared to the enantiopure phase diagram. Thus, it has been proven that the racemic vs. enantiopure coformer leads to increased solubility and improved dissolution of lidocaine due to the low stable form induced by menthol molecular disorder in the lidocaine:dl-menthol cocrystal. To date, the 1:1 lidocaine:dl-menthol cocrystal is the third menthol-based pharmaceutical cocrystal, after the 1:1 lidocaine:l-menthol and the 1:2 lopinavir:l-menthol cocrystals reported in 2010 and 2022, respectively. Overall, this study shows promising potential for designing new materials with both improved characteristics and functional properties in the fields of pharmaceutical sciences and crystal engineering

A thermophysical study of the melting process in alkyl chain metal n-alkanoates: The thallium (I) series

The peculiar thermal behavior of the thallium(I) n-alkanoates series (consisting in several transitions between polymorphic and mesomorphic phases) in comparison with other metallic n-alkanoates series is stated. The allowance of highly accurate adiabatic heat capacity data permits a study of the CH2CH2 contributions to the lattice heat capacity curve at low temperature. Moreover, in this series an anomalous gradual enhancement of the lattice heat capacity has been interpreted from vibrational spectroscopy results as a noncooperative effect due to the internal hindered rotation of the alkyl chain (formation of gauche defects, even in the solid state). The thermodynamics of the “stepwise melting process” from the totally ordered solid at low temperature to the isotropic liquid is based on a revised lattice heat-capacity curve. This was used to evaluate the energy and entropy not only of the clear first order transitions present in the series but also of the described noncooperative effect. The CH2CH2 enthalpy and entropy contribution for this series is estimated and a comparison with the published values for other series is carried out. Moreover, the texture of the mesophases is revealed by polarized light microscopy. © 1999 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69602/2/JCPSA6-111-8-3590-1.pd

Systèmes à tension de vapeur non négligeable : diagrammes T-v et p-T de l'adamantane

A DSC method, designed to determine the melting enthalpy of compounds with non-negligible vapour pressure, is applied to adamantane. This method, based upon the linear dependence of the melting-related thermal effect with the specific volume v, is used to construct the T-v diagram of adamantane through which a melting enthalpy, at the triple point conditions, ΔfusH (+12,4 ± 0,3) kT.mol-1 at Tfus = (543 ± 2) K of is obtained. Also, the specific volume of the vapour phase is extrapolated to (52,7 ± 1,5) cm3.g-1 With this information, a more general description of the p-T diagram for adamantane is put forward

Racemic compound and conglomerate of anhydrous sibutramine hydrochloride: a rare case of relative stability

The thermal behaviours of racemic sibutramine hydrochloride monohydrate as well as that of the anhydrous state were investigated by DSC. A new anhydrous solid was then put in evidence and its crystal structure was solved from XRPD data. This new phase was found to be the conglomerate. Depending on the heat treatment , the initial anhydrous racemic compound may be completely resolved. DSC analyses have shown that the anhydrous conglomerate melts at a higher temperature than the anhydrous racemic compound.Analyse de contrefaçons pharmaceutiques par technologie térahert

Binary Phase Diagram with Non Isomorphous n-Alkanes:C12H26-C15H32. Implication of the Rotator Phase R-I in the Melting Behaviour of Odd-Even and Even-Odd Phase Diagrams

International audienceno abstrac

Solid state landscape of an Active Pharmaceutical Ingredient used for rare diseases

International audienc

Thermal cycling of molecular alloys and eutectics containing alkanes for energy storage

no abstrac

Solid state landscape of an Active Pharmaceutical Ingredient used for rare diseases

International audienc