Method and system of producing microparticles loaded with biologically active drugs, including proteins such as ICAM-1, for controlled release of the drugs in a nasal passageway. The method includes introducing a drug/polymer feed solution and an emulsifier into a first mixing chamber to create an emulsion, then mixing a cross-linking agent together with the emulsion under controlled conditions to create microparticles loaded with the drug. The system includes a first mixing chamber, in which the emulsion is created, having a first port for introducing the drug/polymer solution, and a second port angled substantially perpendicular to the first port for introducing the emulsifier. A second mixing chamber adjacent to the first mixing chamber receives the emulsion and either contains a cross-linking agent or receives a stream of a cross-linking agent to solidify the microparticles. The formed microparticles are filtered and deaggregated to form individual microparticles that then may be formulated for nasal passageway delivery.