ABSTRACT
The gelation behaviour of concentrated micellar solutions of mixtures of a block copolymer of ethylene oxide and styrene oxide (E(137)S(18)E(137)) with one of ethylene oxide and propylene oxide (E(62)P(39)E(62)) has been investigated. Over a wide range of compositions, up to 90 wt.% E(137)S(18)E(137) in the mixture, gelation resembled that of solutions of E(62)P(39)E(62) alone, i.e. they gelled on heating from ambient to body temperature. In related experiments, using the aromatic drug griseofulvin as a comparative standard, it was demonstrated that solubilisation efficiency of dilute micellar solutions of the mixtures with 80 wt.% or more E(137)S(18)E(137) approached that of solutions of E(137)S(18)E(137) alone. Thus it was shown that the mixed system could have both the satisfactory solubilisation capacity of micellar solutions of E(137)S(18)E(137) and the desirable gelation characteristics of E(62)P(39)E(62), and so have potential for use in drug release applications involving in situ gelation.
