Study of Pharmaceutical Coatings by Means of NMR Cryoporometry and SEM Image Analysis
Artikel i vetenskaplig tidskrift, 2012

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.

cellulose

spinodal decomposition

cellulose

cryoporometry

evaporation

porosity

light-scattering

films

image analysis

solvent

polymers

film

OMCTS

mechanism

coating

permeability

NMR spectroscopy

Författare

Catherine Boissier

AstraZeneca Sweden

F. Feidt

The Royal Institute of Technology (KTH)

Lars Nordstierna

Chalmers, Kemi- och bioteknik, Teknisk ytkemi

Journal of Pharmaceutical Sciences

0022-3549 (ISSN)

Vol. 101 2512-2522

Ämneskategorier

Farmakologi och toxikologi

Kemi

DOI

10.1002/jps.23160