Kinetics of a nucleoside release from lactide-caprolactone and lactide-glycolide polymers in vitro

We assessed the rate of release of a model nucleoside (adenosine, 5%, w/w) from nine different lactide-glycolide or lactide-caprolactone polymers. The polymer discs were eluted every second day with an artificial cerebrospina l fluid at the elution rate roughly approximating the brain extracellular f luid formation rate. Adenosine in eluate samples was assayed by HPLC. Three polymers exhibited a relatively constant release of adenosine for over fou r weeks, resulting in micromoIar concentrations of nucleoside in the eluate . This points to the neccessity of further development of polymers of this types as intracerebral nucleoside delivery systems for local treatment of b rain tumors.