WHAT'S THE DEAL WITH PHENYLPROPANOLAMINE?
Phenylopropanolamine (also known as PPA) is a drug which veterinarians have used for many years for the control of urinary incontinence in dogs. We've had consistent success with it, and are aware of only a few reports of minor side effects in pets. Unfortunately, late in 2000 a report was publicized linking strokes in people with the use of PPA. The FDA quickly recommended that people stop using this medication, and many drug suppliers stopped selling it. The end result is that PPA may become increasingly difficult to find, and we may have to consider alternatives for pets taking this medication.
What is it and how's it work?
Phenylpropanolamine, or PPA, is a drug known as a sympathomimetic amine, which means it mimics effects of the sympathetic nervous system. For those of you whose memory of biology is a little rusty (or who haven't taken biology yet), the sympathetic nervous system is involved with the "fight or flight" response in stressful situations. Anything that happens when you're nervous or frightened is controlled by the sympathetic nervous system.
PPA, through an unknown mechanism, causes similar effects in the body. It causes an increase in blood pressure and heart rate, and causes constriction of blood vessels. It also decreases nasal congestion, which is why it's very popular in cold medicines; decreases appetite, which is why it's found in weight control products; and increases the muscle tone of the urethral sphincter (the "valve" that controls when you urinate), which is why it's so helpful for urinary incontinence in dogs.
What's all the fuss about?
Late this year, a study conducted by the Yale University School of Medicine was released. In it, the possible role of PPA in hemorrhagic strokes in people was examined. The conclusion was that there was an increased risk of stroke, especially for woman taking weight loss products. The FDA, because of the severe potential for such a side effect, recommended that people stop using PPA. The response shortly afterwards was that PPA-containing medications were removed from drug store counters, and many suppliers (where we obtain our medications) also stopped carrying PPA in any form.
The report looked at the use of products containing PPA within 3 days of suffering a hemorrhagic stroke, and found that women were at significantly increased risk. The risk of stroke in women using appetite suppressants containing PPA was increased 16-fold, while the risk with cold formulas was about 3 times normal.
So, what now?
Our expectation is that PPA will become increasingly difficult to find, and we may have to use other alternatives for control of urinary incontinence in dogs. Our hope is that, while PPA will be unavailable in over-the-counter form, it may become available again on a prescription-only basis for our use in pets.
Where can I learn more?
You can read the FDA's position at www.fda.org, which contains background information and the FDA's news releases. You can currently (December 2000) find the article itself at the New England Journal of Medicine site, www.nejm.org. We're trying to keep informed about any changes; any client who would like a periodic e-mail update, please send your e-mail address to us here at comments@companionanimalclinic.com, and we'll pass on information as we receive it.