Indications for Fluorouracil
Fluorouracil 5 topical cream is an antimetabolite used for chemotherapy. Antimetabolites, like the name suggests, are a toxic compound that prevent cells from metabolizing, thereby halting cell growth. It is this damage to the metabolism of cells that prevents mutated cells (i.e., carcinoma or sarcoma) from spreading. The medication has no way of specifically targeting only the mutated cells, meaning that it prevents all cell growth within a wide area, which can be quite painful. However, as far as dog skin cancer treatments are concerned, the benefits often greatly outweigh the risks.
Precautions for Fluorouracil
Fluorouracil should not be given to pregnant or nursing dogs, due to it being a teratogen, which lead to a number of different birth defects. It should also not be given to patients suffering from bone marrow suppression, serious infections, poor nutritional states, or a known hypersensitivity to antimetabolites. Patients with blood disorders should only be given fluorouracil under certain conditions, and should be used with great caution. Use with Leucovorin might increase the chances of gastrointestinal toxicity. Also, fluorouracil should never be given to cats, as it is extremely neurotoxic.
Side Effects of Fluorouracil
Like with other forms of chemotherapy, side effects can be extreme. Fluorouracil can lead to vomiting, diarrhea, loss of appetite, ulceration in the mouth and GI tract, neurotoxicity, ataxia, hair loss, and blood dyscrasia.
Dosage for Fluorouracil
Since this drug is designed for use in people, it is considered an extra-label drug in dogs, meaning that no official recommended dosage for canine usage has been published. However, since the therapeutic index (the range in which fluorouracil is actually beneficial) of fluorouracil in dogs is very narrow, dosages should be administered with great care.
Brand/Generic Equivalent of Fluorouracil
Carac, Efudex, Fluoroplex