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