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Featuring Demian Dressler, DVM and Sue Ettinger, DVM, Dip. ACVIM (Oncology), authors of The Dog Cancer Survival Guide

Historical Use Definition

Historical Use: This term suggests evaluating treatments by looking at their use over time, rather than using clinical studies. Some drugs, like aspirin (pain relief) and phenobarbital (anti-seizure), were used before the Food and Drug Administration (FDA) started regulating pharmaceuticals. These drugs, which have strong historical evidence of working in the body, are grandfathered into the system and do not need to go through the lengthy (ten to fifteen years) and extremely expensive (millions of dollars) approval process. Since 1938, new drugs undergo safety and efficacy trials to prove to the FDA that they work for the purpose for which they are intended. Drugs are usually approved for one, fairly narrow use, although their action may be useful in other diseases. Once approved, doctors and veterinarians can prescribe them for their approved purpose, or for any other purpose they judge to be safe and appropriate. A classic example of this is using phenobarbital – grandfather-approved for seizures – as a sedative. This practice, called off-label prescription, is very common, especially in veterinary medicine. Using off-label prescriptions, vets can prescribe a drug approved for humans for use in any other species. Vets may also use a drug approved for a condition in one species in a totally different species, and even for a different condition. There are two chemotherapy drugs approved for use specifically in dogs; both are approved for some types of mast cell tumors: Palladia and Kinavet CA-1. Many, but not all, other chemotherapy treatments used in conventional care have been reviewed for safety and efficacy in dogs, but do not have specific FDA approval. If a treatment (drug or not) has been in use for a long time and is successful, it is considered valid, even if there are no FDA studies “proving” its validity. Most pragmatic vets agree with this point of view, although a few demand more proof.

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