Fate of Hydralazine in Man. I. Reactions under Gastric Conditions

Tetrazolo [5, 1-α] phthalazine (Tetra-P) was detected by GC and GC-MS in extracts of incubation mixtures of hydralazine (HP) in human saliva with simulated gastric juice (SGJ), while 3-methyl-s-triazolo [3, 4-α] phthalazine (MTP) and s-triazolo [3, 4-α] phthalazine (Tri-P) were identified as the main products in the absence of SGJ. Tetra-P was also found in rabbit urine when an aqueous solution of NaNO2 was given before and after the oral administration of HP. The amounts of MTP, Tri-P and Tetra-P formed depended on the pH and incubation time.