Small drug sample fabrication of controlled release polymers using the microextrusion method.

Ethylene vinylacetate polymer (EVA) has been used for many years to fabricate controlled-release polymeric implant devices with which drugs of high or low molecular weight compounds could be delivered with zero-order kinetics. However, because the known fabrication methods such as solvent evaporation, casting and possible shrinkage are not sufficiently controllable we have now developed the microextrusion method with which even small amount of clinically important and expensive drugs can be incorporated into EVA with high reproducibility. We show here that devices produced by the microextrusion method allows for a controlled delivery of several neurotoxic and neurotherapeutic compounds such as alpha-methyl-p-tyrosine, diazepam, quinolinic acid, and phencyclidine. Each substance is slowly released from the polymer, as evidenced by spectrophotometric data, for up to 120 days at daily rates varying from 18.4 microg of phencyclidine to 97.6 microg/day of diazepam. Thus, microextrusion is a valuable method for fabricating controlled-release polymers in which small amounts of scarce drugs can be incorporated. Another advantage of the current procedure is that polymers can be fabricated with very little amount of solvent.