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Nifedipine solid dispersion in micro...

Huang, Jingjun.

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Nifedipine solid dispersion in microparticles of ethylcellulose and Eudragit RL binary blend for drug controlled delivery .

Record Type:	Electronic resources : Monograph/item
Title/Author:	Nifedipine solid dispersion in microparticles of ethylcellulose and Eudragit RL binary blend for drug controlled delivery ./
Author:	Huang, Jingjun.
Description:	126 p.
Notes:	Source: Dissertation Abstracts International, Volume: 67-04, Section: B, page: 1939.
Contained By:	Dissertation Abstracts International67-04B.
Subject:	Chemistry, Pharmaceutical. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3215812
ISBN:	9780542670374

Nifedipine solid dispersion in microparticles of ethylcellulose and Eudragit RL binary blend for drug controlled delivery .
Huang, Jingjun.

Nifedipine solid dispersion in microparticles of ethylcellulose and Eudragit RL binary blend for drug controlled delivery . - 126 p.

Source: Dissertation Abstracts International, Volume: 67-04, Section: B, page: 1939.

Thesis (Ph.D.)--University of the Sciences in Philadelphia, 2006.

In order to develop microparticles for controlled release of a poorly water-soluble drug, nifedipine, microparticles consisting of Eudragit RL RTM (RL) and ethylcellulose (EC) binary blend with different levels of drug loading were prepared using a phase-separation method. The effects of microparticle formulations on the physico-chemical properties, drug physical forms, and nifedipine release kinetics/mechanism were evaluated by polarized light microscopy, differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR) spectroscopy, X-ray powder diffraction (XRPD), UV-visible spectroscopy, stability and drug release studies.

ISBN: 9780542670374Subjects--Topical Terms:

550957
Chemistry, Pharmaceutical.

Nifedipine solid dispersion in microparticles of ethylcellulose and Eudragit RL binary blend for drug controlled delivery .
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245 1 0 $a Nifedipine solid dispersion in microparticles of ethylcellulose and Eudragit RL binary blend for drug controlled delivery .
300 $a 126 p.
500 $a Source: Dissertation Abstracts International, Volume: 67-04, Section: B, page: 1939.
500 $a Adviser: Joseph B. Schwartz.
502 $a Thesis (Ph.D.)--University of the Sciences in Philadelphia, 2006.
520 $a In order to develop microparticles for controlled release of a poorly water-soluble drug, nifedipine, microparticles consisting of Eudragit RL RTM (RL) and ethylcellulose (EC) binary blend with different levels of drug loading were prepared using a phase-separation method. The effects of microparticle formulations on the physico-chemical properties, drug physical forms, and nifedipine release kinetics/mechanism were evaluated by polarized light microscopy, differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR) spectroscopy, X-ray powder diffraction (XRPD), UV-visible spectroscopy, stability and drug release studies.
520 $a The physico-chemical characterization studies demonstrated that depending on drug loading, a nifedipine stable molecular dispersion may exist or coexist with its metastable molecular dispersion in the microparticles. The formation of a nifedipine amorphous molecular dispersion in the microparticles was confirmed by FTIR spectroscopic studies, which demonstrated that there were hydrogen-bond interactions between nifedipine and the polymers at the molecular level. As a result of formation of an amorphous molecular dispersion, nifedipine dissolution inside the microparticles was no longer the rate-limiting step for its release from micro-matrix into the dissolution medium. Instead, the drug diffusion process in matrix became the slowest step for drug release. Consequently, controlled release of nifedipine from microparticles can be achieved by changing the matrix permeability with different ratios of ethylcellulose to Eudragit RTM RL polymer.
520 $a Study results demonstrated that controlled release of nifedipine can be achieved by varying the microparticle composition. The microparticle sizes, shape, size distribution, and drug release rate were influenced by the ratio of RL to EC. Spherical microparticles with a narrow size distribution and a controlled release profile were obtained when the ratio of RL to EC was in the range from 1:1 to 2:1 w/w, whereas, no significant effects of drug loading on the microparticle size, shape, and size distribution were observed. Drug release modeling with the Korsmeyer-Peppas model indicated that nifedipine release from microparticles was controlled by the Fickian diffusion mechanism. Moreover, the regression analysis of drug release data demonstrated that at low levels of drug loading, the release of nifedipine was best described by the Baker & Lonsdale's matrix diffusion model for microspheres containing dissolved drug. The plasticizing effect of nifedipine on the micro-matrices, owing to significant hydrogen-bond interactions between drug and polymers as detected by FTIR spectroscopy, caused a rise in the nifedipine diffusion coefficient in matrices with increasing drug loading. However, at medium levels of drug loading, the formation of nifedipine metastable solitary phase domain, found by solid-state characterization studies, may cause a change in the release mechanism.
590 $a School code: 1379.
650 4 $a Chemistry, Pharmaceutical. $3 550957
650 4 $a Health Sciences, Pharmacy. $3 1017737
690 $a 0491
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710 2 0 $a University of the Sciences in Philadelphia. $3 1017850
773 0 $t Dissertation Abstracts International $g 67-04B.
790 1 0 $a Schwartz, Joseph B., $e advisor
790 $a 1379
791 $a Ph.D.
792 $a 2006
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3215812