Negative inotropic activity of para-substituted diethyl benzylphosphonates related to fostedil

Abstract Several p -substituted diethyl benzylphosphonates related to the calcium antagonist diethyl 4-(2-benzothiazolyl)benzylphosphonate (fostedil) have been studied. They produce a dose-dependent negative inotropic effect on left atrial muscle isolated from guinea pig heart. Some of the compounds are equipotent or slightly more potent than fostedil and diltiazem taken as reference drugs. Structure—activity relationships are discussed.