Study of Pharmaceutical Coatings by Means of NMR Cryoporometry and SEM Image Analysis

QC 20120726
Nuclear magnetic resonance (NMR) cryoporometry and scanning electron microscopy (SEM) image analysis have been used to investigate the size and shape distribution of pores in pharmaceutical coatings. The coatings were made from a mixture of hydroxypropylcellulose (HPC) and ethylcellulose (EC). Upon solvent evaporation from a solution consisting of both the polymers, a solid polymer film is formed, which after removal of the water-soluble HPC consists of a skeleton of EC. A change in the amount of HPC enables modification of the water permeability through the films. By means of NMR cryoporometry, the presence of small pores (radius below 400 nm) was revealed with no significant change in the pore size distribution (PSD) as the HPC content in the films were changed. NMR cryoporometry showed the presence of channels of a characteristic 30-nm length scale in the films that contained more than 22% HPC. Below this threshold, the lack of interconnecting channels seems to prevent complete HPC dissolution and thereby the water permeability. SEM image analysis showed pore sizes that ranged from hundreds of nanometers up to few micrometers. Above the 22% threshold, further increase of HPC in the films resulted in an increased pore volume and wider PSD.

MEDICIN OCH HÄLSOVETENSKAP Medicinska och farmaceutiska grundvetenskaper Farmakologi och toxikologi hsv//swe
MEDICAL AND HEALTH SCIENCES Basic Medicine Pharmacology and Toxicology hsv//eng
NATURVETENSKAP Kemi hsv//swe
NATURAL SCIENCES Chemical Sciences hsv//eng
light-scattering
cryoporometry
polymers
films
coating
cellulose
OMCTS
film
evaporation
mechanism
solvent
NMR spectroscopy
image analysis
porosity
spinodal decomposition
permeability
cellulose

Feidt, FrancoisKTH,Tillämpad fysikalisk kemi(Swepub:kth)u1ig65mt (author)
Nordstierna, Lars,1976Chalmers tekniska högskola,Chalmers University of Technology(Swepub:cth)nlars (author)
AstraZeneca ABTillämpad fysikalisk kemi (creator_code:org_t)

In:Journal of Pharmaceutical Sciences: Elsevier BV101:7, s. 2512-25221520-60170022-3549

By the author/editor: Boissier, Cather ...; Feidt, Francois; Nordstierna, Lar ...

About the subject

MEDICAL AND HEALTH SCIENCES: MEDICAL AND HEAL ...; and Basic Medicine; and Pharmacology and ...

By the university: Chalmers University of Technology; Royal Institute of Technology

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