We previously reported the structureactivity relationships (SAFt) of adibendan (l), a potent and long-acting cardiotonic. This paper describes the synthesis of a novel series of linear, tricyclic fused heterocycles of the 5-6-5 type. The compounds were evaluated for positive inotropic activity in anesthetized rats, cats, and dogs. Changes in left ventricular dP/dt were measured as an index of cardiac contractility. The increase in contractility was not ...
