Amrinone and milrinone are bipyridine
derivatives that are relatively selective
inhibitors of cGMP-inhbited, cyclic AMP
phosphodiesterase (type III).
These agents cause vasodilation
(decreased afterload) and increase myocardial
Milrinone is the agent of choice among
the phosphodiesterase inhibitors for short-term
parenteral support in severe heart failure patients. Oral
formulations are not used due to intolerable side-effects including
increases in mortality.