A method of inhibiting pulmonary hypertensive disease comprising administering to a human in need thereof an effective amount of a compound having the formula ##STR1## wherein R.sup.1 and R.sup.3 are independently hydrogen, --CH.sub.3, ##STR2## wherein Ar is optionally substituted phenyl; R.sup.2 is selected from the group consisting of pyrrolidine, hexamethyleneamino, and piperidino; or a pharmaceutically acceptable salt of solvate thereof.