Solubilisation in aqueous micellar solutions of block copoly(oxyalkylene)s.
The solubilisation capacities of micellar solutions of diblock and triblock copolymers composed of hydrophilic poly(ethylene oxide) and hydrophobic poly(styrene oxide) have been compared using the poorly water-soluble drug griseofulvin as a model solubilisate. Our results showed an increase of solubilisation capacity (expressed as mg griseofulvin per gram of hydrophobic block) with temperature and, for spherical micelles, with core volume before reaching limiting values. A change of micelle shape from spherical to cylindrical (or worm-like) resulting from an increase in micelle aggregation number was accompanied by a further enhancement of solubilisation capacity. Comparison with the solubilisation of the same drug in micellar solutions of block copolymers of poly(ethylene oxide) and poly(1,2-butylene oxide) showed that the solubilisation capacity of a poly(styrene oxide) block was approximately four times that of a poly(1,2-butylene oxide) block for spherical micelles. Solubilisation capacity at 25 degrees C was approximately doubled when griseofulvin was incorporated into a copolymer melt and micelles initially formed from the drug-loaded melt at 65 degrees C rather than by loading the drug into pre-micellised solution at 25 degrees C in the usual manner.
Crothers
Michael
M
School of Pharmacy and Pharmaceutical Sciences, University of Manchester, Manchester M13 9PL, UK.
Zhou
Zhengyuan
Z
Ricardo
Nágila M P S
NM
Yang
Zhuo
Z
Taboada
Pablo
P
Chaibundit
Chiraphon
C
Attwood
David
D
Booth
Colin
C
D008823:Micelles; D019999:Pharmaceutical Solutions / Q000032:analysis / Q000737:chemistry; D011108:Polymers / Q000032:analysis / Q000737:chemistry*; D012995:Solubility; D014867:Water / Q000737:chemistry*
D008823:Micelles; D019999:Pharmaceutical Solutions; D011108:Polymers; D014867:Water