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Effect of excipient porosity on melt...

Long Island University, The Brooklyn Center.

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Effect of excipient porosity on melting point depression of deposited materials.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Effect of excipient porosity on melting point depression of deposited materials./
Author:	Khairuzzaman, A. K. M.
Description:	218 p.
Notes:	Adviser: Robert A. Bellantone.
Contained By:	Dissertation Abstracts International68-10B.
Subject:	Health Sciences, Pharmacology. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3285788
ISBN:	9780549281047

Effect of excipient porosity on melting point depression of deposited materials.
Khairuzzaman, A. K. M.

Effect of excipient porosity on melting point depression of deposited materials. - 218 p.

Adviser: Robert A. Bellantone.

Thesis (Ph.D.)--Long Island University, The Brooklyn Center, 2008.

Key Words. Differential Scanning Calorimetry; Melting point depression; Kelvin equation; Thermodynamic model; Stress relaxation.

ISBN: 9780549281047Subjects--Topical Terms:

1017717
Health Sciences, Pharmacology.

Effect of excipient porosity on melting point depression of deposited materials.
LDR:04858nam 2200337 a 45 001 852058
005 20100629
008 100629s2008 ||||||||||||||||| ||eng d
020 $a 9780549281047
035 $a (UMI)AAI3285788
035 $a AAI3285788
040 $a UMI $c UMI
100 1 $a Khairuzzaman, A. K. M. $3 1017736
245 1 0 $a Effect of excipient porosity on melting point depression of deposited materials.
300 $a 218 p.
500 $a Adviser: Robert A. Bellantone.
500 $a Source: Dissertation Abstracts International, Volume: 68-10, Section: B, page: 6611.
502 $a Thesis (Ph.D.)--Long Island University, The Brooklyn Center, 2008.
520 $a Key Words. Differential Scanning Calorimetry; Melting point depression; Kelvin equation; Thermodynamic model; Stress relaxation.
520 $a The effect of excipient porosity on melting point depression of confined liquids and deposited solids in the pores of solid pharmaceutical excipients was evaluated using differential scanning calorimetry (DSC). Pore size distributions were measured using nitrogen gas adsorption. It was seen that the melting occurred over a range of temperatures, which corresponded to the distribution of pore sizes. Based on such observations, a thermodynamic model was established to explain these effects on the basis of surface area energies, which can be related to the Kelvin equation.
520 $a Various grades of porous silicon dioxide were allowed to soak in purified water, USP into their pores and DSC was conducted using various cooling rates to -30°C, isothermally maintained for 7 minutes, and heated slowly to 6°C at various heating rates. A melting point depression during the heating cycle was observed at -10°C to -2°C for the ice confined in pores of various diameters. The effect of cooling rate on the melt behavior of the confined ice was observed as a function of intensity of the "early" melting phase. (Here, early refers to the melting that occurs in a range of temperatures that is lower than the nominal freezing or melting temperature. The DSC peaks that are observed are referred to as "satellite" peaks.) Satellite melt peaks became less prevalent with slower cooling and disappeared at a cooling rate of 0.01°C/min.
520 $a The effect of porosity on melting point depressions of cyclohexane was also studied. Cyclohexane was soaked into Syloid 244 and Syloid 74 followed by freezing in DSC at a cooling rate of 1°C/min. and heating at 0.25°C/min. Similarly, two endothermic melt peaks were observed, one from each grade of Syloid-cyclohexane matrix. The satellite melt peak represented the distribution of melting of frozen confined cyclohexane starting from -7°C to -0.8°C with a peak at -3.6°C from Syloid 244, while the satellite melting phase started as low as -13°C and ended at -1.9°C, with the peak at -6.0°C from the pores of Syloid 74. This investigation further suggested that porosity can also have significant effects on the melting point depression of organic solvents (or any other solvents), which does not expand upon freezing.
520 $a The effect of pore sizes on uptake of various aqueous solutions was also studied using DSC. For a small molecule like ethanol (contrary to the bigger molecule like PEG 400), it was easy for the solution to get into the pores of Syloid, as can be seen from the satellite melt peak from DSC thermogram. However, the solutes did affect the uptake of the solvent into the pores, as evidenced in diminishing satellite melt peaks on the thermograms.
520 $a In addition to studying solvent melting behavior, the melting behavior of solid compounds deposited into the pores was also investigated. Initially, sucrose was deposited into the pores of Syloid, and it was seen that the melting peak of sucrose was significantly lowered. Similarly, melting point depressions were also observed from deposited model drugs namely: danazol, prednisolone, hydrocortisone and D(-) norgestrel. The deposition of all these model drugs into the pores of Syloid contributed a very high surface to volume ratio of the deposited material. Therefore, the surface energy was increased significantly that contributed the shift of melting in the downfield of DSC spectra. A trend in such melting point depression was found to be related to the average pore diameter of Syloid and the transport of the prepared solution into the pores of Syloid. Such decrease in the melting point of poorly soluble drugs may be an indication that their solubility has increased significantly.
590 $a School code: 0198.
650 4 $a Health Sciences, Pharmacology. $3 1017717
650 4 $a Health Sciences, Pharmacy. $3 1017737
690 $a 0419
690 $a 0572
710 2 $a Long Island University, The Brooklyn Center. $3 1017735
773 0 $t Dissertation Abstracts International $g 68-10B.
790 $a 0198
790 1 0 $a Bellantone, Robert A., $e advisor
791 $a Ph.D.
792 $a 2008
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3285788