Fipronil is a contact insecticide and acaricide without systemic effect that belongs to the chemical class of the phenylpyrazoles. It is highly effective mainly against fleas an against several tick and lice species of dogs and cats. It is not effective against internal parasites.

Fipronil is massively used in numberless spot-ons but also in low-cost sprays, shampoos, soaps, etc. for dogs and cats worldwide. It is also used as a pour-on for cattle in some countries (mainly Latin America) against horn flies, cattle ticks and a few myiasis. It is also used massivle against agricultural and household pests.

The table below indicates some usual dosing recommendations for fipronil issued by manufacturers or documented in the scientific literature. They may not be approved in some countries.

Dosing recommendations for FIPRONIL
Delivery Parasites Dose (against fipronil-susceptible parasites)
Spot-on (10%) Fleas 6.7-13.3 mg/kg; 4-5 weeks protection.
Spot-on (10%) Lice (Trichodectes canis) 6.7-13.3 mg/kg
Spot-on (10%) Ticks 6.7-13.3 mg/kg (>90%): Amblyomma americanum, Dermacentor reticulatus, Dermacentor variabilis, Ixodes ricinus, Ixodes scapularis, Rhipicephalus sanguineus. Protection dep. on species.
Spray (0.25%) Fleas 7.5 mg/kg (3 ml solution/kg); 3-6 weeks protection.
Spray (0.25%) Lice (Trichodectes canis) 7.5-15 mg/kg (3 ml solution/kg)
Spray (0.25%) Lice (Neotrombicula autumnalis) 7.5-15 mg/kg (3 ml solution/kg); rep monthly until season end.
Spray (0.25%) Lice (Cheyletiella spp) 7.5 mg/kg (3 ml solution/kg); rep after 4 weeks.
Spray (0.25%) Sarcoptes scabiei 7.5 mg/kg (3 ml solution/kg); rep twice after 3 & 6 weeks.
Delivery Parasites Dose (against fipronil-susceptible parasites)
Spot (10%-on) Fleas ≤50 mg/kg (0.5 ml/animal >1 kg); 4-5 weeks protection.
Spot (10%-on) Lice (Felicola subrostratus) ≤50 mg/kg (0.5 ml/animal >1 kg)
Spot (10%-on) Otodectes cynotis 2 drops (eq. to 9mg/animal) in each ear. In addition treatment of ectopic lice with spot-on or spray at the rec. dose.
Spray (0.25%) Fleas 7.5 mg/kg (3 ml solution/kg); 4-5 weeks protection.
Spray (0.25%) Lice (Felicola subrostratus) 7.5 mg/kg (3 ml solution/kg)
Delivery Parasites Dose (against fipronil-susceptible parasites)
Pour-on (1%) Cattle ticks 1 ml/10 kg = 1 mg/kg; 2-3 weeks protection
Pour-on (1%) Horn flies 1 ml/10 kg = 1 mg/kg; protectionn >95% after 4 days; ~85% after 7 days; 70% after 4 weeks.
Pour-on (1%) Screwworms 1 ml/10 kg = 1 mg/kg; 2-3 weeks protection
Pour-on (1%) Human bot flies 1 ml/10 kg = 1 mg/kg; 4 weeks protection

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In most finished products, efficacy and safety depend not only on the amount of active ingredient(s) but also on their formulations (i.e. the type and amount of so-called inert ingredients), particularly in topical pour-ons and spot-ons. These inert ingredients can significantly affect the pharmacokinetic behavior (e.g. absorption through the skin, distribution within the body, spreading throughout the body surface, etc). Generic products usually contain the same amount of active ingredient(s) as the original product, but often in quite different formulations. In many cases, the curative (therapeutic) efficacy of the different formulations is quite comparable, but the protective (prophylactic) efficacy that determines the length of protection against re-infestations may be rather different.

Dosing recommendations for antiparasitics depend on national regulations. National regulatory authorities determine whether a product is approved for a given indication, i.e. use on a particular host at a specific dose and against a specific parasiteCheck the labels of the products available in your country for specific information on approved indications.

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