Carbostyril derivatives as combined thromboxane synthetase and cyclic-amp phosphodiesterase inhibitors

The invention concerns a method of inhibiting both thromboxane synthetase and cyclic-AMP phosphodiesterase in a mammal having a disease characterized by elevated thromboxane levels or an imbalance of prostacyclin/thromboxane levels with a compound of the formula: (I) or a pharmaceutically acceptable acid addition salt or ester thereof, wherein: X is chosen from the group consisting of: and a covalent bond in which R1 is H, alkyl having 1-6 carbon atoms, optionally substituted phenyl or optionally substituted phenyl lower alkyl, when R2 is H or OH, or R1 and R2 taken together represent oxo, alkylidene having 1-6 carbon atoms or optionally substituted benzylidene; R3 is H or alkyl having 1-6 carbon atoms, R4 is H and R3 and R4 are either cis or trans to each other, or R3 and R4 taken together represent a covalent bond; n is an integer from 0-3; Het is 1-imidazolyl or 3-pyridyl; and the dotted line represents an optional covalent bond.