Mixtures of triblock copolymers E 62P 39E 62 and E 137S 18E 137: Potential for drug delivery from in situ gelling micellar formulations

Abstract

The gelation behaviour of concentrated micellar solutions of mixtures of a block copolymer of ethylene oxide and styrene oxide (E 137S 18E 137) with one of ethylene oxide and propylene oxide (E 62P 39E 62) has been investigated. Over a wide range of compositions, up to 90 wt.% E 137S 18E 137 in the mixture, gelation resembled that of solutions of E 62P 39E 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 137S 18E 137 approached that of solutions of E 137S 18E 137 alone. Thus it was shown that the mixed system could have both the satisfactory solubilisation capacity of micellar solutions of E 137S 18E 137 and the desirable gelation characteristics of E 62P 39E 62, and so have potential for use in drug release applications involving in situ gelation.