The Effect of 1-Hydrazinophthalazine in Hypertension

The compound 1-hydrazinophthalazine appears to be be an antihypertensive drug of only moderate potency.Based on experience with 50 cases of arterial hypertension, it was found most effective in patients with unsuccessful sympathectomy, malignant hypertension, and neurogenic hypertension.It was relatively ineffective in renal hypertension and in a group of miscellaneous conditions.Chronic administration by mouth in outpatients was feasible.ANEW compound, 1-hydrazinophthalazine (C-5968), has been shown by Reubil to cause hemodynamic effects which suggest that it may act as an antihyper- tensive agent.After single doses effective renal plasma flow was increased, while blood pressure was moderately lowered in hypertensive pa- tients.'Freis and Finnerty2 found that the cold pressor test was modified by the drug, as well as the vasopressor "overshoot" following the Valsalva maneuver.Pulse volume in digits also increased.Grimson and his co-workers3 failed to demonstrate sustained effects on repeated administration.l-Hydrazinophthalazine is the basic struc- ture (fig. 1) for several substituted compounds which have the peculiar pharmacologic prop- erties of increasing renal and femoral blood flow in the dog and rabbit while lowering blood pressure,4 a characteristic not enjoyed by most other circulatory depressants.The drug is sympatholytic in some animals in that it antago- nizes the pressor action of epinephrine3; that of hypertensin is also blocked.5' 8 In man, nor- epinephrine may be partly opposed.There is suggestive evidence that the depressor effect occurs through action on the hind or mid- brain.46 Methyl and benzene substituted com- pounds appear to differ but little.