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By Wendy C. Brooks, DVM, DipABVP
Educational Director,

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Lufenuron (Program)

Brand Name: Program, and included in Sentinel

Available as oral suspension; and in 45 mg, 90 mg, 204.9 mg, & 409.8 mg tablets

Available as injectable for cats

Included in Sentinel Heartworm Preventative for dogs


Flea control for pets used to be all about shampoos, sprays, foggers, flea collars and powders. The U.S. market had been long in search of a flea product that was safe, convenient, and effective and many companies were racing to bring out their new product first. Ciba Animal Health won this battle in 1995 with the approval of lufenuron for use in U.S. pets. The introduction of lufenuron marked what is called the "revolution" in flea control where products shifted towards monthly oral and topical products and away from the labor-intensive materials of the past. Lufenuron does not kills fleas but it is highly effective at ending flea reproduction. This means that it is best used in combination with other products. It is available as an over-the-counter oral medication or as an "every six month" injectable for cats.

How this Medication Works

Insects are protected in the world by a hard exoskeleton made of a material called chitin. Lufenuron inhibits the production of chitin in insects.

By the time a flea has reached adulthood and is taking blood meals from a pet, it has made all the chitin it needs and is not directly affected by the lufenuron it is drinking in the pet's blood. The female flea, however, is largely drinking blood to support egg-laying (up to 40 eggs daily) and the larvae developing inside these eggs must make chitin in order to chip their way out of the egg. If the mother flea has passed along a big dose of lufenuron to her eggs, they will not be able to hatch.

Adult fleas feeding on a pet will be continually producing the black specks of digested blood called flea dirt. This material is highly nutritious for larvae developing in the environment but if this flea dirt is packed with lufenuron, the larvae will not be able to grow normal exoskeletons and they will die.

The injectable formula for cats was designed as an alternative to the relatively unpopular oral liquid. Like the oral product, injectable lufenuron is stored in body fat. One injection is effective for 6 months.

Fleas are not the only organisms to contain chitin. Apparently some fungi also are affected by lufenuron. An anti-ringworm dose, which is much higher than the flea preventive dose, has been published to aid in the treatment of dermatophytosis (more commonly known as ringworm.) The efficacy of lufenuron for fungal diseases has not panned out, however, and this unapproved use of lufenuron should be considered as only an adjunct to more traditional therapies, if at all. Lufenuron should not be used as a sole therapy for ringworm. As for other fungi, lufenuron use seems cost prohibitive but may be of benefit as adjunctive therapy.

Side Effects

Oral lufenuron must be given on a full stomach in order to be properly absorbed into the body.

Since Program works on enzyme systems that are unique to insects, no other side effects have been reported even in animals fed hundreds of times the recommended dose.

Interactions with Other Drugs

Program does not interact with other medications. Program is therefore compatible with all other treatments.

It is important to note that with the advent of popular top-spot treatments for fleas, special attention should be paid to the development of resistance to these products. Experience with other insects tells us that resistance can develop in 12 to 15 generations. In order to preserve these new insecticides, it is important to consider what is called integrated pest management. What this means is that insecticides should be rotated or combined with insect development inhibitors such as lufenuron or insect growth regulators such as methoprene or pyriproxifen (substances that interfere with the maturation of flea larvae). Adding a second product that breaks the flea life cycle in another stage is helpful in preventing resistance.  Lufenuron may be used in combination with any of the popular effective topicals or oral products to achieve this end.

Compare flea control products.

Concerns and Cautions

In order for lufenuron to work, fleas must bite the pet, which is potentially a problem for pets who are allergic to fleas. For pets with flea bite allergy, lufenuron would best be combined with a product that actually kills fleas. Currently there is no flea product that can kill fleas before they bite.

Lufenuron must be given on a full stomach.

Pets must be at least 6 weeks of age to begin taking lufenuron.

It is our policy not to give dosing information over the Internet.


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