Production of dry sterile dosage forms often involves large-scale mixing of the API with one or more excipients. To achieve a homogeneous mixture, the particle size distribution of the excipient(s) must match that of the API. In a one-step-operation, spray drying can turn a sterile solution of the excipient into sterile particles of the required size with no risk of introducing impurities – a well-known problem if milling is used. Spray dryers for sterile production are completely "tailor made" for the duty.