Human Drugs for Your Cat

A lengthy approval process results in fewer feline-specific medications.

When a human drug is prescribed for your ailing cat, you may wonder: Is this medication actually safe for my animal?

An estimated 300 drugs carry Food and Drug Administration (FDA) approval for companion animals, but many more human drugs are being prescribed for pets today. This off-label use of drugs for a different species or purpose is common – even though they have not undergone the tests required of drugs specifically for animals. 

The reason that few cat-specific drugs are sold is because the route of approval for any new animal drug is long, circuitous and costly. The time from the drawing board to the veterinarians office is five to 12 years, according to drug companies. But government agencies responsible for the safety of animal pharmaceuticals say that the timeline is actually shorter than the drug companies say, and that the review processes are being improved.

To speed up the paperwork, the Food and Drug Administrations Center for Veterinary Medicine (CVM) is working towards electronic submissions, and is working very diligently to decrease the backlog, says Beth Luddy, DVM, veterinary medical officer. One proposal is to legislate industry user fees to fund the review of animal drug applications as with human drugs, so that more CVM staff can be hired.

According to CVM officials, this would eliminate the pending backlog within two years of enactment, and within five years would ensure that 90 percent of submissions are completed within 180 days.

Research is Required
Currently, Luddy explains, What we confront is that so many drugs are for novel applications (such as behavior modification), and we have to take time to contact experts in the field and do lots of research to make sure the claim is true (and) to learn about the clinical disease. Proof of safety and efficacy are not sacrificed to save time.

The CVM makes the final rulings on all animal drugs. New animal vaccines undergo a similar regulatory process under the United States Department of Agriculture (USDA) and its Center for Veterinary Biologics (CVB). Vaccines average one to two years from application to approval, according to CVB chief staff veterinarian Byron Rippke, DVM, as long as the technology is pretty straight forward. But new concepts – such as recombinant vaccines – usually take longer.

Much of the research time is spent following biological testing processes, but sometimes the government has questions you didnt anticipate, and it makes you go back, adding another couple of years to the timeframe, notes Rami Cobb, BVSc, vice president of pharmaceutical research and development, Fort Dodge Animal Health. A couple of years ago, it was estimated that it costs $40 million for a new (animal) drug (to get to market) – and thats if all goes well. The government requirements are greater than when I started 12 years ago, and it drives a lot of companies out of the arena.

Companies spend at least two years just getting research underway, says Ann Jernigan, DVM, head of Discovery, Pfizer Animal Health. After this discovery period, exploratory development takes another one to two years as different drug formulations and doses are tried, determining the safety margin and general effects of the drug. Later, in a clinical testing phase of two years or longer, safe dosages are tested in pets.

Only after extensive field trials can a company compile all its research and manufacturing data for the regulatory agency. It takes about six months for USDA vaccine review and approval, but sources say that applications to the CVM often take up to two years for final drug licensing.

Although cats metabolize drugs uniquely – which can make the use of human or dog drugs dangerous in even small quantities – For the most part, off-label use is safe, notes Elizabeth Hardie, DVM, North Carolina State University College of Veterinary Medicine. If theres a successful, human disease-treating drug, theres often no reason to develop new animal drugs. There are a number of drugs that will never be approved (for animals) because of the costs of testing.

CVM offers expedited review status for breakthrough drugs which have new medical benefits. These drugs are assessed under shorter timeframes, but to qualify the drug must be for a debilitating or life-threatening disease.

Unique Vaccines Are An Exception
Currently, the USDA offers a conditional license that allows a vaccine that is unique – or prevents a new disease – to be marketed more speedily. Safety studies still must be completed, but the approval time can be cut several months by shortening the efficacy testing, says Rippke. The company must later finish all studies before it can get full licensing.

Overall, the USDA requires similar forms and testing procedures for vaccines as the FDA does for drugs, but Rippke says that things generally move faster because the technology of vaccines is a little more defined, compared to therapeutic (drug) treatments where youre going on new, unproven ideas. (For vaccines) the level of proof of efficacy varies, he says, depending on the vaccine, the disease and how long the vaccine is supposed to work. If you have a brand new agent, sometimes having a lower level of efficacy is more important than having no vaccine at all.

Our charge is to ensure that no worthless, contaminated, dangerous or harmful product gets on the market, Rippke concludes. Were constantly looking for more efficient ways to do our work (but) theres always that balancing act going on.