Piperonyl butoxide is used as a potentiator or synergist in many pesticide formulations, including carbamates, organophosphates, organochlorines, pyrethrins, pyrethroids, and d-limonene. It decreases breakdown of the above-mentioned pesticides in the animal or insect's body by inhibiting mixed function oxidase enzymes and makes the pesticide more toxic to the insect—and the host. Animals that are debilitated or have decreased drug metabolizing capability become more susceptible to the pesticide. However, toxins that must be activated in the body to a toxic form are frequently less toxic when piperonyl butoxide exposure occurs at the same time. This potentiating or synergistic effect has been seen in many species, including cats, dogs, rats, and humans. Cimetidine, a drug that reduces stomach acid secretion by blocking gastric H₂ receptors, and the antibiotic chloramphenicol have the same effect.

Last full review/revision March 2012 by Ramesh C. Gupta, DVM, MVSc, PhD, DABT, FACT, FATS