The present invention is directed to the use of microparticles to protect the
pharmaceutical effectiveness of a pharmaceutically active agent. According to one
embodiment, a pharmaceutically acceptable suspension is provided that comprises
microparticles and a pharmaceutically active agent. This pharmaceutically acceptable
suspension is then exposed to a component or condition that is incompatible with
the pharmaceutically active agent, such that the microparticles provide a pharmaceutical
effectiveness that is greater than it would have been in the absence of the microparticles.
Preferably, the microparticles result in a pharmaceutical effectiveness of the
pharmaceutically active agent that is at least 10% greater than the pharmaceutical
effectiveness of the pharmaceutically active agent would have been in the absence
of the micro particles. Polymer microparticles, such as polystyrene microparticles,
are one preferred class of microparticles. The microparticles preferably range
from 0.01 to 100 microns in largest dimension, more preferably 0.1 to 10 microns
in largest dimension. The microparticles are preferably provided in an amount of
0.1 to 1 wt % within the suspension. Agents comprising polynucleotides, including
cells, plasmids and viral vectors, are a preferred class of pharmaceutically active
agent. Other embodiments on the invention are directed to pharmaceutically acceptable
suspensions, medical devices for parenteral injection, and methods of treatment.
