Metabolism
• Diazinon metabolism has been studied in mice, rats, guinea pigs, dogs, hens, cattle and sheep.34 The primary metabolic
route was cleavage of the P-O-pyrimidine group followed by oxidation and dealkylation of the alkyl substituents on the
pyrimidine ring.34
• Diazinon is oxygenated to an intermediate compound, phosphooxythiran, which in turn undergoes desulfurization to form
diazoxon. Diazoxon is a more potent ChE inhibitor compared to diazinon itself.12 Diazoxon can be detoxified by paraoxanase
1/arylestase (PON1) enzymes35 and can be deactivated by hydrolysis, desulfurization and deoxygenation to form
2-isopropyl-4-methyl-6-hydroxypyrimidine (IMHP), diethylthiophosphate (DETP) and diethylphosphate (DEP).12
• In rats orally exposed to diazinon, liver metabolism reduced the systemically bioavailable amount of diazinon by 65% during
the first pass through the liver.10
• Diazinon is rapidly metabolized with most metabolites being excreted in the urine within 48 hours.34