Process for the production of nanoporous foamed active substance-containing preparations, wherein the active substance is present embedded in a pharmaceutically acceptable polymer, wherein, in stage a) loading of a polymeric molding composition or a polymer melt with a propellant is effected at a pressure and at a temperature at which the propellant is in the supercritical state, in stage b) heating of the laden polymer molding compound or melt is carried out under pressure at a temperature which lies in the range from −40 to +60° C., preferably −20 to +55° C., and especially preferably 0 to +50° C. around the glass transition temperature of the unladen (prior to loading) polymeric molding compound and in stage c) a depressurization of the polymeric molding compound or melt laden in stage a) and heated under pressure in stage b) is effected out with a depressurization rate in the range from 15,000 to 200,000 MPa/sec.