Thermochemical study of two anhydrous polymorphs of caffeine

Pinto, Susana; Diogo, Hermı́nio P.

doi:10.1016/j.jct.2006.04.008

Cited by 42 publications

(34 citation statements)

References 29 publications

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“…For the anhydrous phase of CAFII, the major feature in the diffraction pattern Figure 1 Crystal structures of anhydrous caffeine polymorphs, along the crystallographic c-axis. Temperatures and nomenclature are taken according to the literature [40]. The a-form is highly disordered about each crystallographic site.…”

Section: Resultsmentioning

confidence: 99%

“…Caffeine has been the subject of immense interest to the solid-state research community [28,[39][40][41][42] and has served as a fundamental example of the benefits of co-crystallisation on the physico-chemical properties of drug materials [43]. This compound exists in a variety of solid forms, for which the structures of two anhydrous polymorphs and one monohydrate are known, Fig.…”

Section: Introductionmentioning

confidence: 99%

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The effect of ball mass on the mechanochemical transformation of a single-component organic system: anhydrous caffeine

2018

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ABSTARCTMechanochemical methodologies, particularly ball milling, have become commonplace in many laboratories. In the present work, we examine the effects of milling ball mass on the polymorphic conversion of anhydrous caffeine. By investigating a single-phase system, the rate-limiting step of particle-particle contact formation is eliminated. It is found that larger milling balls lead to considerably faster conversion rates. Modelling of the transformation rate suggests that a single, time-independent rate constant is insufficient to describe the transformation. Instead, a convolution of at least two rate-determining processes is required to correctly describe the transformation. This suggests that the early stages of the transformation are governed only by the number of particle-ball collisions. As the reaction proceeds, these collisions less frequently involve reactant, and the rate becomes limited by mass transport, or mixing, even in originally single-phase systems, which become multi-phase as the product is formed. Larger milling balls are less hindered by poorly mixed material. This likely results from a combination of higher impact energies and higher surface areas associated with the larger milling balls. Such insight is important for the selective and targeted design of mechanochemical processes.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The effect of ball mass on the mechanochemical transformation of a single-component organic system: anhydrous caffeine

2018

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“…The DSC curve of pure CAF exhibited a single endothermic peak at 235.5 C which corresponding to crystalline CAF melting point. 34,35 As amorphous polymers, FG did not show any fusion peaks or phase transitions. In the case of CAF loaded FG lm, there was an endothermic peak of crystal CAF melting peak which indicates the crystallization during the slow water evaporation process.…”

Section: 30mentioning

confidence: 90%

Fish gelatin nanofibers prevent drug crystallization and enable ultrafast delivery

et al. 2017

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For drug delivery, uncontrolled drug crystallization is the most important and well-described problem which affects the compatibility between target drug and carrier polymer matrix. The crystallization of drugs makes a drug delivery system unstable and it causes a drop the drug loading efficiency and unpredictable release behavior. Recently, the electrospinning process which has rapid solvent evaporation speed has been proposed to prevent the drug crystallization during the drug loading process. In the present study, a fastdissolving nanofibrous drug delivery carrier was prepared via electrospinning of aqueous fish gelatin as the polymer carrier and caffeine as the hydrophilic model drug under environmentally friendly conditions. Fish gelatin electrospinning was able to produce caffeine loaded gelatin nanofibers with a diameter of 200-220 nm. The X-ray diffraction (XRD) and differential scanning calorimetry (DSC) data clearly showed that the amorphous state of caffeine was well incorporated into ultrafine nanofibrous carrier whereas crystalline caffeine was dispersed into conventional fish gelatin film. Fish gelatin nanofibers were able to load two times more caffeine (20 mg ml À1) than conventional caffeine-loaded polymer nanofibers. The fish gelatin nanofibrous mat has good flexibility compared to film due to its interporous nanofiber network. The fish gelatin nanofibrous mats disintegrated within 1.5 s, 27 times faster than films. Fish gelatin nanofibers also showed that most caffeine was released within 10 seconds, which is faster than fish gelatin film and free caffeine drugs. These fish gelatin nanofibers showed 10 times faster caffeine release rates than other caffeine loaded polymer nanofibers. Electrospun fish gelatin nanofibrous mats can be used in biomedical fields especially for the ultra fast delivery of hydrophilic drugs or active ingredients.

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“…The heating chamber was heated to a desired temperature (313.15, 323.15, 333.15, or 343.15 K). Liquid CO 2 was subsequently pumped into the system using a high pressure pump until a targeted pressure was achieved (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26). After equilibrium condition was achieved in 4 h, the sampling tube (1 ml) was disconnected from the system.…”

Section: Solubility Of Catechin In Sc-comentioning

confidence: 99%

Catechin sublimation pressure and solubility in supercritical carbon dioxide

Soetaredjo¹,

Ismadji²,

Yuliana³

et al. 2013

Fluid Phase Equilibria

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a b s t r a c tSolubility of (+)-catechin in SC-CO 2 was measured at several temperatures (313.15, 323.15, 333.15 and 343.15 K) and pressure in the range of 12-26 MPa using ethanol as the co-solvent (5 mol.%). The experimental data were used for the correlation of density dependent solute solubility parameters. The equations of Chrastil, del Valle and Aguilera, Adachi and Lu, González, and Méndez-Santiago and Tejawere fitted very well for the solubility of (+)-catechin. The rate of mass loss of (+)-catechin showed that its sublimation pressure is very low, an indication of the stability of the compound. Thermogravimetric analysis was used to determine the sublimation pressure.

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Thermochemical study of two anhydrous polymorphs of caffeine

Cited by 42 publications

References 29 publications

The effect of ball mass on the mechanochemical transformation of a single-component organic system: anhydrous caffeine

The effect of ball mass on the mechanochemical transformation of a single-component organic system: anhydrous caffeine

Fish gelatin nanofibers prevent drug crystallization and enable ultrafast delivery

Catechin sublimation pressure and solubility in supercritical carbon dioxide

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