From Dog

Imidacloprid is a first newer generation insecticide released by Bayer for control of fleas in 1996[1].

It is a topical spot-on that spreads over the skin by translocation and is not absorbed systemically. It is a neonicotinoid (chloronicotinyl nitroguanidine) that acts as an agonist on the postsynaptic nicotinic acetylcholine receptors. By keeping the receptor channels open, it causes constant neuronal stimulation and therefore paralysis and death of adult fleas.

Imidacloprid has a very high margin of safety as a result of the affinity of the compound for insect acetylcholine receptors over mammalian acetylcholine receptors. Imidacloprid is absorbed through flea intersegmental membranes and does not require ingestion by the flea to be effective[2].

Like selamectin, imidacloprid kills adult fleas rapidly, with 100% efficacy achieved within 12 to 24 hours after application. Efficacy decreases by 28 days after application[3].

Imidacloprid also has good larvicidal activity, although the principles of integrated pest management would discourage the use of a single chemical as both an adulticide and a larvicide. This drug is apparently safe to use on lactating, feeding and pregnant queens, and kittens from 12 weeks of age.


  1. Schwassman, M & Logas, D (2010) How to treat common parasites safely. In August, JR (Ed): Consultations in feline internal medicine. Vol 6. Elsevier Saunders, Philadelphia. pp:390
  2. Schnieder, T, Wolken, S & Mencke, N (2008) Comparative speed of efficacy of imidacloprid against Ctenocephalides felis in experimentally infested cats. Compend Contin Educ Pract Vet 30:18
  3. Jacobs, DE et al (1997) Duration of activity of imidacloprid, a novel adulticide for flea control against Ctenocephalides felis in cats. Vet Rec 140:259