{HEAD ~ A beneficial agent} present in the devices is released at a controlled rate and in {TAIL ~ effective amounts} as the polymers erode over time 
is released in
{ HEAD ~ A beneficial agent } present in the devices is released at a controlled rate and in { TAIL ~ effective amounts } as the polymers erode over time
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH REL REL OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH