Unconventional dissolution methodologies

Pillay, Viness; Fassihi, Reza

doi:10.1021/js990139b

Cited by 64 publications

(42 citation statements)

References 55 publications

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“…Dissolution is a key phenomenon encountered in various processes, for example for drug delivery, quality control in pharmacology [1] or in the food-processing industry [2,3]. Dissolution also takes part in many chemical processes in the mining industry [4][5][6][7], batteries [8,9], fertilizer production [10], or the recycling industry [11].…”

Section: Introductionmentioning

confidence: 99%

A method for phenomenological and chemical kinetics study of autocatalytic reactive dissolution by optical microscopy. The case of uranium dioxide dissolution in nitric acid media

Marc¹,

Magnaldo²,

Godard³

et al. 2018

EPJ Nuclear Sci. Technol.

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Abstract. Dissolution is a milestone of the head-end of hydrometallurgical processes, as the stabilization rates of the chemical elements determine the process performance and hold-up. This study aims at better understanding the chemical and physico-chemical phenomena of uranium dioxide dissolution reactions in nitric acid media in the Purex process, which separates the reusable materials and the final wastes of the spent nuclear fuels. It has been documented that the attack of sintering-manufactured uranium dioxide solids occurs through preferential attack sites, which leads to the development of cracks in the solids. Optical microscopy observations show that in some cases, the development of these cracks leads to the solid cleavage. It is shown here that the dissolution of the detached fragments is much slower than the process of the complete cleavage of the solid, and occurs with no disturbing phenomena, like gas bubbling. This fact has motivated the measurement of dissolution kinetics using optical microscopy and image processing. By further discriminating between external resistance and chemical reaction, the "true" chemical kinetics of the reaction have been measured, and the highly autocatalytic nature of the reaction confirmed. Based on these results, the constants of the chemical reactions kinetic laws have also been evaluated.

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Section: Introductionmentioning

confidence: 99%

A method for phenomenological and chemical kinetics study of autocatalytic reactive dissolution by optical microscopy. The case of uranium dioxide dissolution in nitric acid media

Marc¹,

Magnaldo²,

Godard³

et al. 2018

EPJ Nuclear Sci. Technol.

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“…[19][20][21][22] As described above, the cylinder system at 30 dpm was faster than at 5 dpm by a factor of about 4 (14 vs 52 minutes to achieve a 50% APAP release). However, the changes in paddle speeds apparently resulted in relatively less discriminating profiles.…”

Section: Effects Of Agitation Ratesmentioning

confidence: 70%

“…The percent release of APAP was observed to depend on the screen size (mesh). Three levels of screen size (20,40, and 78 mesh) were tested for APAP release under different dip speeds (10 and 30 dpm) in 3 pH buffers. Table 2 shows only the most discriminating data (in pH 5.0 buffer and at 10 dpm).…”

Section: Effects Of Screen Sizesmentioning

confidence: 99%

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In vitro evaluation of dissolution behavior for a colon-specific drug delivery system (CODES™) in multi-pH media using United States Pharmacopeia apparatus II and III

Li¹,

Yang²,

Ferguson³

et al. 2002

AAPS PharmSciTech

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United States Pharmacopeia dissolution apparatus II (paddle) and III (reciprocating cylinder) coupled with automatic sampling devices and software were used to develop a testing procedure for acquiring release profiles of colon-specific drug delivery system (CODES™) drug formulations in multi-pH media using acetaminophen (APAP) as a model drug. System suitability was examined. Several important instrument parameters and formulation variables were evaluated. Release profiles in artificial gastric fluid (pH 1.2), intestinal fluid (pH 6.8), and pH 5.0 buffer were determined. As expected, the percent release of APAP from coated core tablets was highly pH dependent. A release profile exhibiting a negligible release in pH 1.2 and 6.8 buffers followed by a rapid release in pH 5.0 buffer was established. The drug release in pH 5.0 buffer increased significantly with the increase in the dip or paddle speed but was inversely related to the screen mesh observed at lower dip speeds. It was interesting to note that there was a close similarity (f 2 = 80.6) between the release profiles at dip speed 5 dpm and paddle speed 100 rpm. In addition, the release rate was reduced significantly with the increase in acid-soluble Eudragit E coating levels, but lactulose loading showed only a negligible effect. In conclusion, the established reciprocating cylinder method at lower agitation rates can give release profiles equivalent to those for the paddle procedure for CODES™ drug pH-gradient release testing. Apparatus III was demonstrated to be more convenient and efficient than apparatus II by providing various programmable options in sampling times, agitation rates, and medium changes, which suggested that the apparatus III approach has better potential for in vitro evaluation of colon-specific drug delivery systems.

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“…Application of MDT provides more accurate drug release rate as compared to the t x% (time for x% drug dissolved) approach and is determined as the sum of the individual periods of time during which a specific fraction of the total dose is released. 20) The following equation may be used to calculate the MDT for each percentage point:…”

Section: S L Sl Sl L Slmentioning

confidence: 99%

Physicochemical Characterization and Dissolution Study of Solid Dispersions of Ketoconazole with Nicotinamide

Aggarwal¹,

Jain²

2011

Chem. Pharm. Bull.

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Purpose: The aim of the present study was to improve the solubility and dissolution rate of a poorly watersoluble drug ketoconazole using solid dispersion technique. Methods: Solid dispersions of ketoconazole were prepared in ratios of 90 : 10, 70 : 30, 50 : 50, 30 : 70 and 10 : 90 by the melting method using nicotinamide as carrier. These solid dispersions were characterized by differential scanning calorimetry (DSC), powder X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy to ascertain if there were any physicochemical interactions between drug and carrier that could affect dissolution. Solubility and dissolution studies were conducted with pure ketoconazole, physical mixtures and solid dispersions. Results: Solubility studies indicated that nicotinamide increased significantly the solubility of ketoconazole in water. The Gibbs free energy (D DG°t r ) values were negative indicating the spontaneous nature of ketoconazole solubilization, and it decreased with increase in concentration of the carrier, demonstrating that the reaction became more favorable as the concentration of the carrier increased. The cumulative release of ketoconazole within 120 min from solid dispersion at a drug-tonicotinamide ratio of 10 : 90 (w/w) was 6 times higher than the pure drug in phosphate buffer of pH 6.8. Conclusion: Solid state characterization indicated that there is no interaction between ketoconazole and nicotinamide in the solid state. In contrast to the very slow dissolution rate of pure ketoconazole, the dispersion of the drug in nicotinamide considerably enhanced the dissolution rate. The drug dissolution rate was highest at a drug-tonicotinamide ratio of 10 : 90 (w/w).

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Unconventional dissolution methodologies

Cited by 64 publications

References 55 publications

A method for phenomenological and chemical kinetics study of autocatalytic reactive dissolution by optical microscopy. The case of uranium dioxide dissolution in nitric acid media

A method for phenomenological and chemical kinetics study of autocatalytic reactive dissolution by optical microscopy. The case of uranium dioxide dissolution in nitric acid media

In vitro evaluation of dissolution behavior for a colon-specific drug delivery system (CODES™) in multi-pH media using United States Pharmacopeia apparatus II and III

Physicochemical Characterization and Dissolution Study of Solid Dispersions of Ketoconazole with Nicotinamide

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