In another embodiment the drug pump can include {HEAD ~ several valves}, each valve being in {TAIL ~ communication} with one of the reservoirs and in fluid communication with the outlet port 
In another embodiment the drug pump can include { HEAD ~ several valves } , each valve being in { TAIL ~ communication } with one of the reservoirs and in fluid communication with the outlet port
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH