NSAIDs + Pesticides - Drug Interactions

Chronic exposure to lindane and other chlorinated pesticides canslightly increase rate of metabolism of phenazone (antipyrine)and phenylbutazone

Clinical evidence,mechanism, importance and management

A study in 26 men occupationally exposed to a mixture of insecticides, predominantly DDT, chlordane and lindane, found that half-life of phenazone 10 or 15 mg/kg was reduced from 13.1 hours,in a group of 33 unexposed subjects, to 7.7 hrs in exposed group (See reference number 1). The significance of this is unclear as changes in working practices have reduced occupational exposure to such chemicals.

The plasma half-life of phenylbutazone in a group of men who regularly used chlorinated insecticide sprays (mainly lindane) as part of their work, was found to be 20 % shorter (51 hours) than in a control group (64 hours), due, it is believed, to enzyme-inducing effects of pes-

ticides (See reference number 2). This modest increase in rate of metabolism is of doubtful direct clinical importance, but it illustrates changed metabolism that can occur in those exposed to environmental chemical agents.

Kolmodin B,Azarnoff DL, Sjöqvist F. Effect of environmental factors on drug metabolism:decreased plasma half-life of antipyrine in workers exposed to chlorinated hydrocarbon insecticides. Clin Pharmacol Ther (1969) 10, 638–42.

Kolmodin-Hedman B. Decreased plasma half-life of phenylbutazone in workers exposed tochlorinated pesticides. Eur J Clin Pharmacol (1973) 5,195–8.