Phenylpropanolamine

Major Uses

Phenylpropanolamine is a stimulant generally used to control urinary incontinence in female dogs. It may also be used as a decongestant in animals. Phenylpropanolamine works by increasing sphincter tone in the urethra to stop inadvertent urine leakage. It is sometimes used in combination with diethylstilbestrol, which is an estrogen.

Phenylpropanolamine acts as a stimulant in the sympathetic nervous system, releasing norepinephrine. After release, the neurotransmitter causes constriction of blood vessels, increased heart rate, and increased blood pressure. Constriction of blood vessels inside the nasal cavity is what reduces congestion. Although phenylpropanolamine is not approved by the Food and Drug Administration for use in animals, it is prescribed legally as an extra-label drug by veterinarians.

Common Precautions

Side effects most commonly associated with use of phenylpropanolamine include high blood pressure, restlessness, and lack of appetite. Stroke and other serious adverse events have been reported with use of this medication. Phenylpropanolamine should be used cautiously in animals with a history of diabetes, high blood pressure, glaucoma, overactive thyroid, or heart disease.

This medication should not be used to control urinary incontinence until other causes of the condition, such as bladder infection and kidney disease, have been ruled out. This drug may interact with other medications or supplements, including aspirin, tricyclic antidepressants, and ephedrine. When used along with L-Deprenyl, phenylpropanolamine can cause unpredictable fluctuations in blood pressure.

Phenylpropanolamine should not be used in animals with a known allergy or hypersensitivity to the drug. Any known or suspected overdose should be reported to a veterinarian right away.

Storage

Phenylpropanolamine should be stored in its original packaging, away from sources of light. It should not be kept within reach of children or animals.

Administration

Phenylpropanolamine is available in chewables in strengths of 25 mg, 50 mg, and 75 mg, and as an oral suspension. It is also available through compounding pharmacies and can be made to order in a variety of concentrations.

The typical dose of phenylpropanolamine in dogs is 12.5 to 50 mg three times daily, depending on the weight of the animal. In cats, the typical dose is 12.5 mg per cat three times daily or one 75 mg sustained-release capsule once daily.

Doses may vary in different species, when the drug is given by a different route or concurrently with other medications, and with regards to a patient's age, breed, and health status. A veterinarian's dosing instructions and/or those printed on the medication label should be followed closely.

If a dose of phenylpropanolamine is missed, it should be given as soon as possible. If it is almost time for the next dose, the missed dose should be skipped and the normal schedule resumed. Two doses of this medication should not be give at once.