Prescriptions for Healthier Animals

by Food and Drug Administration (FDA)

Tina and Baron have both seen better days. Tina Gilliam, of Gaithersburg, Md., slowly gets out of bed in the morning and carefully pulls on her socks to avoid the pain she feels when she tries to move too fast. Her golden retriever, Baron, also lifts himself slowly from the floor next to her bed. As he limps after her to the medicine cabinet, his gait is much like hers — slow, stiff and deliberate — for like Gilliam, Baron suffers from arthritis.

Gilliam shakes a pill out of a bottle, and swallows it with a few sips of water. She shakes another pill out of a different bottle, pops it into Baron's mouth, and massages his throat while he swallows it. Soon, the pain and stiffness for both will lessen, and the two companions will go out for their morning walk.

Gilliam has just taken Lodine, and Baron has taken EtoGesic. The pills are different sizes, shapes, and colors. But if Gilliam were to check the label on each, she would find the same active ingredient: etodolac.

Gilliam and Baron are part of an increasingly common phenomenon in which humans and animals often take similar drugs for similar diseases.

Admittedly, the animal drug's active ingredient may be in a concentration different from that found in the human drug. The animal drug might even have different inactive ingredients. But that drug can alleviate the same pain, eliminate the same symptoms, and cure the same illness in pets as its counterpart can in people.

Veterinarians have been prescribing approved animal drugs that are similar to human drugs for years. And, since the passing of the Animal Medicinal Drug Use Clarification Act of 1994 (AMDUCA), it has been legal for vets to treat pets with human drugs that have not been approved for animals. Veterinarians also prescribe drugs not approved for humans, such as flea control medications.

Veterinary science is working doggedly to keep up with the expectations of pet owners, who represent the majority of Americans. More than 37 percent of American households own dogs, 34 percent own cats, and 16 percent own both, according to consumer marketing firm NPD Group Inc.

These guardians of 58 million dogs and 72 million cats want first-rate treatment for their four-legged friends. "As people are seeing more complex and sophisticated drugs for themselves, they want that same quality for their pets," says Melanie Berson, DVM, director of the Division of Therapeutic Drugs for Non-Food Animals within the Food and Drug Administration's Center for Veterinary Medicine (CVM).

Recognizing this need, animal pharmaceutical companies continue to submit applications to CVM, the organization within FDA that approves drugs designed for animals. The applications fall into three drug categories: an existing animal drug to be used for a different illness, an existing animal drug to be used for a different type of animal, and an entirely new animal drug.

Drugs Approved for Animals

Nearly 300 drugs currently on the market have been approved by FDA for dogs, cats, and horses — otherwise known as companion animals. Many of these have the same active ingredient found in their human drug counterparts.

Drugs for animals are given new trade names to distinguish them from the human drugs, and different companies may manufacture them. GastroGard, for example, used to treat stomach ulcers in horses, has the same active ingredient as Prilosec, used to treat severe and persistent heartburn in people. GastroGard is made by Merial Limited in London, while Prilosec is a product of AstraZeneca PLC, also in London.

"The approval process for a new companion animal drug is similar to the approval of a new human drug," says Berson. "The major difference is that the size of the clinical trials for animal drugs is many times smaller." A human clinical trial typically involves thousands of test subjects, but an animal trial involves only hundreds, according to Berson.

Despite their smaller clinical trials, pet drugs must meet standards similar to those for human drugs. And pet drug manufacturers "must apply the same rigorous scientific standards to studies and the manufacturing processes must be in accordance with Good Manufacturing Practices," says Ann Stohlman, VMD, a veterinary medical officer at CVM.

Drugs Used But Not Approved for Animals

The practice of giving animals drugs that have been approved for humans but not for animals is known as prescribing "off-label," or "extralabel." Extralabel use can also mean prescribing a drug to a different species, for a different condition, or in a different dosage than that for which the drug was approved. For example, a veterinarian may prescribe a lower dose of an arthritis drug approved for dogs to a feline with an inflamed joint.

FDA restricts extralabel use of human drugs in food-producing animals. This precaution is taken to prevent drug residues in animals from entering the human food chain and threatening public health. But extralabel use of human drugs in companion animals is not as restricted.

While these human drugs have been tested in some animals before being tested in humans, they have not gone through the comprehensive studies FDA requires to approve them for use in animals. And drug manufacturers cannot advertise to veterinarians or pet owners a drug that has not been approved for animals.

Even so, it is a long-standing veterinary practice to treat pets with the latest human drugs. "In vet medicine we've relied on human drugs for years," says Michael Bassett, DVM, owner and medical director of Pet Dominion Animal Hospital in Rockville, Md. "They don't develop new drugs for animals fast enough."

Veterinarian Daniel Negola tries to rely on the animal drugs when possible. "We use the drugs approved for animals first," says the owner of Negola's Ark Veterinary Hospital in Gaithersburg, Md. "Only when they're not working or if they're not available for a specific problem do we go to the next source — human drugs."

How do vets know how much of a human drug to prescribe to an animal when it is not approved for animal use? The veterinary research community shares study results through published papers, seminars, and books, says Neal Bataller, a veterinarian in CVM's Office of Surveillance and Compliance. Formulations found to be effective are documented in numerous veterinary drug handbooks and textbooks.

The handbooks provide such information as the drug's indications and usage, contraindications, dosage, precautions, and adverse reactions. There are also veterinary handbooks and texts that explain what drugs to use to treat other pets — such as lizards, rabbits, and birds — for which specific FDA approvals do not exist, adds Bataller.

About the Author

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FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.