3-Hydrazinopyridazine derivatives as inhibitors of pyridoxal-phosphate dependent enzymes.

A series 3-hydrazinopyridazine derivatives with anti-hypertensive properties was studied as inhibitors of pyridoxal-phosphate dependent enzymes. All the compounds with a free hydrazino group were found to be strong inhibitors in vitro. In vivo inactive compounds became active at doses which exert a hypotensive action. The significance of this inhibition is discussed.