[Evaluation of a pyridopyridazine as a drug with marked antihypertensive properties (author's transl)].

Compound BQ 22-708 is a pyridopyridazine with marked antihypertensive effects on experimentally induced hypertension. At this study hemodynamic reactions were controlled in 5 patients with resistent hypertension, two of them with the complication of hypertensive, two of them with the complication of hypertensive crisis, after oral administration of a mean dose of 11 mg BQ 22-708 (range 5 to 15 mg). Mean arterial pressure was reduced by 40 mm Hg. The onset of drug activity occurred 10 to 20 minutes after application. Maximum was reached after 90 to 180 minutes, whereas the antihypertensive effect lasted for about 5 to 6 hours. Peripheral resistance was reduced by about 50%. Heart rate and cardiac output increased. In patients with normal cardiac function stroke volume remained constant, whereas in patients with heart insufficiency an increase occurred. BQ 22-708 led to a slight reduction in pulmonary artery pressure and pulmonary capillary wedge pressure. Right atrial mean pressure remained unchanged. Additional treatment with a beta-adrenergic-blocking-agent or a drug with Ca-antagonistic-activities is indicated for inhibition of BQ-related increase of heart-rate.