Program is now also available in an injectable form for cats which is administered every six months. It is important to treat all animals in the household, as untreated animals will serve as a source of reinfestation for treated animals. In order for Program to be correctly absorbed from the intestinal tract, it must be dissolved in fat. It is administered every thirty days, and once absorbed into the body, is stored in the fat and slowly released into the animal's bloodstream. When the adult flea takes a blood meal, the Program is taken in by the flea, and interferes with egg production.
Program is approved for both dogs and cats six weeks of age and over.
Because it is not an insecticide, it does not add to the toxicity of other insecticides. Therefore, as stated above, insecticides may be used initially along with Program in order to control existing adult flea populations, and kill new juveniles as they hatch from eggs laid prior to the administration of Program. A potential disadvantage to Program is that the flea must bite the host in order to ingest the drug. For dogs with flea bite allergies, even a few bites can cause severe itching. An advantage is that Program is considered extremely nontoxic to mammals because it interferes with the reproductive processes of the flea, which are not found in mammals.