One‐step preparation of double‐walled microspheres

Multilayered microspheres for drug delivery can be produced by several methods, but most techniques involve several stages and often lead to layers of non‐uniform thickness. The solcent evaporation method of producing double‐layered microspheres described here svoids these difficulties, a single step yielding micrespheres consisting of an inner core of polymer surrounded by a second polymer. The theory is presented and the characterization of the microspheres discussed.