A high viscosity composition which according to the invention comprises at least one polyoxyethylene-polyoxypropylene-block copolymer (poloxamer) having the structural formula HO(C2H4O)a (C3H6O)b (C2H4O)a H and having an average molecular weight of above 6000 at least one additional polymer having an average molecular weight of above 150000, and a dispersion medium, comprising at least one freezing point depressing dispersant and at least one freezing point non-depressing dispersant. The composition is heatable above the body temperature of a mammal and coolable below 0° C. within a predetermined temperature range.
