Stabilized dispersions are provided for the delivery of a bioactive agent. The dispersions preferably comprise a plurality of perforated microstructures dispersed in a suspension medium that typically comprises a liquid fluorochemical. As density variations between the suspended particles and suspension medium are minimized and attractive forces between microstructures are attenuated, the disclosed dispersions are particularly resistant to degradation, such as by settling or flocculation. In particularly preferred embodiments the stabilized dispersions may be directly administered to the lung of a patient using an endotracheal tube or bronchoscope.