An impermeable reservoir is divided into {TAIL ~ a water swellable agent chamber} and {HEAD ~ an active agent formulation chamber} 
An impermeable reservoir is divided into { TAIL ~ a water swellable agent chamber } and { HEAD ~ an active agent formulation chamber }
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD