Process Induced Disorder in Crystalline Materials:Differentiating Defective Crystals from the Amorphous Form of Griseofulvin

Feng, Tao; Pinal, Rodolfo; Carvajal, Micaela

doi:10.1002/jps.21219

Cited by 121 publications

(101 citation statements)

References 33 publications

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“…Additionally, the triplet at 1600 cm −1 becomes a doublet in the amorphous form and several other doublet peaks such as those at~1210 and 1340 cm −1 become single peaks. Similar observations can be made in the FT-Raman data with increased diffusion in the C-H stretching region at~3000 cm −1 , a doublet becoming a single peak at~640 cm −1 , and a significant reduction in peak intensity at~840 cm −1 with the amorphous form of GRIS, with similar observations made by other researchers (38).…”

Section: Physicochemical Characterizationsupporting

confidence: 90%

Thermal Processing of PVP- and HPMC-Based Amorphous Solid Dispersions

et al. 2015

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Abstract. Thermal processing technologies continue to gain interest in pharmaceutical manufacturing. However, the types and grades of polymers that can be utilized in common thermal processing technologies, such as hot-melt extrusion (HME), are often limited by thermal or rheological factors. The objectives of the present study were to compare and contrast two thermal processing methods, HME and KinetiSol® Dispersing (KSD), and investigate the influence of polymer type, polymer molecular weight, and drug loading on the ability to produce amorphous solid dispersions (ASDs) containing the model compound griseofulvin (GRIS). Dispersions were analyzed by a variety of imaging, solid-state, thermal, and solution-state techniques. Dispersions were prepared by both HME and KSD using polyvinylpyrrolidone (PVP) K17 or hydroxypropyl methylcellulose (HPMC) E5. Dispersions were only prepared by KSD using higher molecular weight grades of HPMC and PVP, as these could not be extruded under the conditions selected. Powder X-ray diffraction (PXRD) analysis showed that dispersions prepared by HME were amorphous at 10% and 20% drug load; however, it showed significant crystallinity at 40% drug load. PXRD analysis of KSD samples showed all formulations and drug loads to be amorphous with the exception of trace crystallinity seen in PVP K17 and PVP K30 samples at 40% drug load. These results were further supported by other analytical techniques. KSD produced amorphous dispersions at higher drug loads than could be prepared by HME, as well as with higher molecular weight polymers that were not processable by HME, due to its higher rate of shear and torque output.

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Section: Physicochemical Characterizationsupporting

confidence: 90%

Thermal Processing of PVP- and HPMC-Based Amorphous Solid Dispersions

et al. 2015

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“…7, all binary solid dispersions, ITSDs, and ETSDs showed an absence of the characteristic melting endotherm of sulfathiazole, confirming a solid solution of an amorphous form of sulfathiazole dispersed in the polymeric porous carrier matrix at the molecular level (25)(26)(27). While preparing the PM, a partial disorientation of the organized crystalline structure of sulfathiazole occurs due to the size reduction, which partially disrupts the crystalline structure (28,29). This phenomenon is confirmed by the low intensity endothermic peak at 175°C in the DSC thermograph of the PM and the absence of a second endothermic peak, as shown in Fig.…”

Section: Modulated Differential Scanning Calorimetrymentioning

confidence: 87%

Evaluation of Colloidal Solid Dispersions: Physiochemical Considerations and In Vitro Release Profile

Patel¹,

Dave²

2013

AAPS PharmSciTech

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Abstract. Colloidal solid dispersion is an innovative breakthrough in the pharmaceutical industry that overcomes the solubility-related issue of poorly soluble drugs by using an amorphous approach and also the stability-related issue by means of a complex formation phenomenon using different carrier materials. In the present study, a newly developed adsorption method is introduced to incorporate a high-energy sulfathiazole-polyvinylpyrrolidone (Plasdone® K-29/32) solid dispersion on porous silicon dioxide (Syloid® 244FP). Different ternary systems of sulfathiazole-Plasdone® K-29/32-Syloid® 244FP were prepared (1:1:2, 1:1:3, and 1:2:2) and categorized depending on the mechanism by which Syloid® 244FP was incorporated. Modulated differential scanning calorimetry (MDSC), X-ray diffraction, Fourier transform infrared spectroscopy, and in vitro dissolution studies were conducted to characterize the ternary systems. The X-ray diffraction and MDSC data showed a lack of crystallinity in all internal and external ternary systems, suggesting a loss of the crystallinity of sulfathiazole compared to the physical mixtures. USP apparatus II was used to measure the in vitro dissolution rate of the prepared systems at 75 rpm in different media. The dissolution rate of the optimum ratio (1:2:2) containing an internal ternary solid dispersion system was found to be three times higher than that of the external and physical systems. Thus, the porous silicon dioxide incorporated into the conventional binary solid dispersion acted as a carrier to disperse the complex and increase the dissolution rate.

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“…The water loss after milling can be explained by evaporation due to localized heating at newly cleaved surfaces during milling. Due to high mechanical and thermal stresses, the average milling temperature in a bench-top ball mill can rise by as much as 125°C to 180°C (21,32). Water freed from the adipic acid surfaces could have readily vaporized inside the milling jar.…”

Section: From Sem Images Inmentioning

confidence: 99%

Effect of Milling on DSC Thermogram of Excipient Adipic Acid

Kwek

Yuen

et al. 2010

AAPS PharmSciTech

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Abstract. The purpose of this research was to investigate why and how mechanical milling results in an unexpected shift in differential scanning calorimetry (DSC) measured fusion enthalpy (∆ fus H) and melting point (T m ) of adipic acid, a pharmaceutical excipient. Hyper differential scanning calorimetry (hyper-DSC) was used to characterize adipic acid before and after ball-milling. An experimental study was conducted to evaluate previous postulations such as electrostatic charging using the Faraday cage method, crystallinity loss using powder X-ray diffraction (PXRD), thermal annealing using DSC, impurities removal using thermal gravimetric analysis (TGA) and Karl Fischer titration. DSC thermograms showed that after milling, the values of ∆ fus H and T m were increased by approximately 9% and 5 K, respectively. Previous suggestions of increased electrostatic attraction, change in particle size distribution, and thermal annealing during measurements did not explain the differences. Instead, theoretical analysis and experimental findings suggested that the residual solvent (water) plays a key role. Water entrapped as inclusions inside adipic acid during solution crystallization was partially evaporated by localized heating at the cleaved surfaces during milling. The correlation between the removal of water and melting properties measured was shown via drying and crystallization experiments. These findings show that milling can reduce residual solvent content and causes a shift in DSC results.

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Process Induced Disorder in Crystalline Materials:Differentiating Defective Crystals from the Amorphous Form of Griseofulvin

Cited by 121 publications

References 33 publications

Thermal Processing of PVP- and HPMC-Based Amorphous Solid Dispersions

Thermal Processing of PVP- and HPMC-Based Amorphous Solid Dispersions

Evaluation of Colloidal Solid Dispersions: Physiochemical Considerations and In Vitro Release Profile

Effect of Milling on DSC Thermogram of Excipient Adipic Acid

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