5 PY 6 Q {HEAD ~ pyridin 2 amines} or pharmaceutically acceptable acid addition salts thereof are useful cardiotonics, where Q is hydrogen or lower alkyl, and PY is 4 pyridinyl or 4 pyridinyl having {TAIL ~ one or two lower alkyl substituents} 
5 PY 6 Q { HEAD ~ pyridin 2 amines } or pharmaceutically acceptable acid addition salts thereof are useful cardiotonics , where Q is hydrogen or lower alkyl , and PY is 4 pyridinyl or 4 pyridinyl having { TAIL ~ one or two lower alkyl substituents }
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL