From Cat

Fipronil is an anthelmintic and insecticidal drug commonly available for use in control of fleas on cats, sold as Frontline. Frontline also contains S-methoprene.

Fipronil is an insecticide and acaricide belonging to the phenylpyrazole family. It acts by interacting with ligand-gated chloride channels, in particular those gated by the neurotransmitter gamma-aminobutyric acid (GABA), thereby blocking pre- and post-synaptic transfer of chloride ions across cell membranes. This results in uncontrolled activity of the central nervous system and death of insects or acarines.

Fipronil kills fleas within 24 hours, ticks (Dermacentor variabilis, Rhipicephalus sanguineus, Ixodes scapularis, Ixodes ricinus, Haemaphysalis longicornis, Haemaphysalis flava, Haemaphysalis campanulata) and lice within 48 hours post-exposure[1].

When used in combination with (S)-Methoprene (Frontline), this drug is effective:

  • against infestations with fleas, ticks and/or biting lice[2]
  • at elimination of fleas (Ctenocephalides felis) and insecticidal efficacy against new infestations with adult fleas persists for 4 weeks
  • prevention of the multiplication of fleas by inhibiting the development of eggs (ovicidal activity), larvae and pupae (larvicidal activity) originating from eggs laid by adult fleas for 6 weeks after application.
  • limination of ticks (Ixodes ricinus, Dermacentor variabilis, Rhipicephalus sanguineus). The product has a persistent acaricidal efficacy for up to 2 weeks against ticks[3]
  • elimination of biting lice (Felicola subrostratus).


  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. Dryden MW (2009) Flea and tick control in the 21st century: challenges and opportunities. Vet Dermatol 20(5-6):435-440
  3. Baxter C et al (2009) Dermatoses caused by infestations of immature Ixodes spp. on dogs and cats in Sydney, Australia. Aust Vet J 87(5):182-187