Pyrazon (Pyramin, Pyrazonl, PCA, HS-119) {[5-Amino-4-chloro-3-oxo-2- 
pheny1-(2H)-pyridazine ] 
The urine of rabbits fed with pyrazon was hydrolyzed and analyzed by 
means of thin-layer chromatography. Approximately half the amount of 
pyrazon administered orally to rabbits was excreted in the urine within 24 
hours of ingestion in the form of the unchanged chemical and its metabolite 
the 2-(p-hydroxyphenyl) analog. Urinary excretion products resulting from 
oral administration of tech. pyrazon included not only unchanged pyrazon 
and the p-hydroxy metabolite, but also isopyrazon, present in the tech. 
formulation as an impurity, and its p-hydroxy metabolite. Similar results 
were obtained with cats and dogs, although in contrast to rabbits more p- 
hydroxy metabolite was excreted than unchanged pyrazon (973). 
Studies with pyrazon indicated that 5-amino—4-chloro-3-oxo-(2H)- 
pyridazine was formed after application to beets (456). A second metab-~ 
olite was also observed in subsequent studies but was not identified (1353). 
Resistant rec beets, Beta vulgaris L., were treated with pyrazon tritiated 
in the phenyl ring. A combination of gas liquid chromatography, infrared 
Spectroscopy and thin layer were used to identify the metabolite as the N- 
glucosamine of pyrazon (1211). 
4-Amino-5-chloro-3-oxo-(2H)-pyridazine was also found in soil treated 
with pyrazon (456). 

Pyrazon 
ne NeTucose 

281 
