Indoxacarb is an ectoparasiticide belonging to the oxadiazine chemical family. After being converted into a metabolite, indoxacarb is active against adult, larval and egg stages of insects. In fleas, in addition to its adulticidal activity, indoxacarb activity on the developing larval stages in the immediate surroundings of the treated pet has been demonstrated.
Indoxacarb is a pro-drug that requires bioactivation by the insect enzymes to exert its pharmacodynamic effects. It enters the insect primarily through ingestion but is also absorbed, to a lesser degree, through the insect cuticle. In the mid-gut of susceptible insect species, the insect’s enzymes remove the carbomethoxy group from parent indoxacarb, and convert it into its biologically active form. The bioactivated metabolite acts as a voltage-dependent sodium channel antagonist in insects, by blocking the sodium channels that regulate the flow of sodium ions in the insect’s nervous system. This results in a rapid cessation of feeding within 0 to 4 hours after treatment followed by cessation of egg laying (oviposition), paralysis and death occurring within 4 to 48 hours.
Following a single spot-on application of the product, indoxacarb can still be detected in both skin and hair coat after 4 weeks post-treatment. Absorption through the skin also occurs, but this systemic absorption is partial and not relevant for the clinical efficacy. The absorbed indoxacarb is extensively metabolised by the liver to a variety of metabolites. The major route of excretion is in faeces.