Polymer-drug interactions and wetting of solid dispersions.
We demonstrate the ability of drugs to influence the wetting of solid dispersion tablets in unexpected ways. Five model drugs of different water solubility and ability to interact with the involved polymers were incorporated in hydrophilic polymer matrices, made of either hydroxypropyl methylcellulose (HPMC) or polyvinyl pyrrolidone (PVP). The physical mixtures of all combinations of drug and polymer presented surface hydrophobicities, as measured by the equilibrium advancing contact angle of water, which are expected for materials that do not influence the interactions of each other with water. However, the solid dispersions containing HPMC deviated from this regular behaviour and displayed contact angles below those of the pure compounds involved, either drug or polymer. This behaviour is explained by changed surface exposure of HPMC side groups, as a result of changes in intermolecular hydrogen bonds. In addition to water contact angle measurements, we employed NMR imaging to monitor the time course of water ingress and swelling.
Dahlberg
Carina
C
YKI, Institute for Surface Chemistry, Box 5607, SE-114 86 Stockholm, Sweden. carina.dahlberg@yki.se
Millqvist-Fureby
Anna
A
Schuleit
Michael
M
Furó
István
I
D055598:Chemical Phenomena; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D004347:Drug Interactions; D057927:Hydrophobic and Hydrophilic Interactions; D065347:Hypromellose Derivatives; D008747:Methylcellulose / Q000031:analogs & derivatives / Q000737:chemistry; D015394:Molecular Structure; D004364:Pharmaceutical Preparations / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D011205:Povidone / Q000737:chemistry; D012995:Solubility; D013499:Surface Properties; D013607:Tablets / Q000737:chemistry; D013678:Technology, Pharmaceutical / Q000295:instrumentation / Q000379:methods
D004364:Pharmaceutical Preparations; D011108:Polymers; D013607:Tablets; D065347:Hypromellose Derivatives; D008747:Methylcellulose; D011205:Povidone