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Insect Growth Regulators (IGR's) & Insect Development Inhibitors (IDI's)
Veterinary & Aquatic Services Department, Drs. Foster & Smith
Flea - Tick - External Parasites
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Generic Name
IGR's include methoprene, fenoxycarb, pyriproxyfen,

IDI's include lufenuron, diflubenzuron

Brand Names
Precor, Nylar

Type of Drug
Treatment and prevention of flea infestations.

Form and Storage
Liquid or pellet tablet should be stored in a cool, dry location out of sunlight.

Indications for Use
Note that the IGRs and IDIs do not kill the adult fleas, so to be most effective they should be used along with a product that does kill the adults (adulticide). If there is little risk of flea infestation, the IGRs and IDIs may be enough to prevent a flea infestation. However, if flea problems already exist, or the risk is high, it is best to also use an adulticide.

General Information
IRGs and IDIs differ from traditional flea product ingredients in that their main activity is against the immature forms of the flea. The IGRs mimic the juvenile growth hormone of fleas. The juvenile growth hormone is what keeps the fleas from developing into more mature forms. When the levels of juvenile growth hormone decrease, the larva form matures. The IGRs keep this development from occurring and the immature forms of the flea fail to molt and death occurs. The IDIs inhibit the synthesis of a substance called chitin. Chitin is necessary for the formation of the hard outside skin (cuticle) of the flea. No chitin, no adult flea.

Usual Dose and Administration
Many IGRs and IDIs are used in the environment as ingredients in foggers and sprays. They are also applied to cats and dogs, or given orally or by injection. Remember, at this point there are no effective IGRs or IDIs for ticks.

Side Effects
Tablets may cause vomiting or diarrhea.

IGR's break down in sunlight.

Test small area of carpet/fabric for colorfastness if used as a spray. Stay off the carpet while damp.

IGR's do not kill adult fleas.

Drug or Food Interactions
None known.

Contact your veterinarian or the Animal Poison Control Center if you think your pet may have accidentally received or been given an overdose of the medication.

Because IGRs and IDIs mimic insect hormones or alter a unique insect process (the making of chitin, which mammals do not make), they are extremely safe.



Insect growth regulators (IGRs) and insect development inhibitors (IDIs) are relatively new components of flea and tick products that are very safe. They have no affect on adult fleas, but prevent immature forms of the flea from developing.

Keep this and all other medications out of the reach of children and pets.

If you think your pet has been poisoned...

Contact your veterinarian or one of the Animal Poison Hotlines (listed below) if you think your pet may have accidentally received or been given an overdose of the medication.

**ASPCA Animal Poison Control Center - 24-hour service available throughout North America.

1-888-4ANI-HELP (1-888-426-4435). $65.00 per case, billed to caller's credit card.

Follow-up calls can be made for no additional charge by dialing 888-299-2973.

There is no charge when the call involves a product covered by the Animal Product Safety Service.

**Pet Poison Helpline - 24-hour service available throughout North America for pet owners and veterinary professionals who require assistance with treating a potentially poisoned pet.

1-800-213-6680 ($59.00 per incident). Staffed 24-hours a day.

Updated 6/20/17

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