Paroxetine

What is paroxetine?

Paroxetine (brand names: Paxil®, Brisdelle®) is a selective serotonin reuptake inhibitor (SSRI) antidepressant used to treat canine aggression, anxiety, and stereotypic/obsessive compulsive behaviors. In cats, it has been used to treat aggression, urine marking, and other behavior problems.

Its use in cats, dogs, or birds to treat behavioral disorders is off label (extra label). Many drugs are commonly prescribed for off-label use in veterinary medicine. “Off label” means the drug is being used in a way that has not been reviewed or approved by the U.S. Food and Drug Administration (FDA) or Health Canada. In these instances, follow your veterinarian’s directions and cautions carefully, as they may be significantly different from those on the label.

How is paroxetine given?

• Paroxetine is given by mouth in the form of a tablet, capsule, or liquid suspension.
• Shake liquid forms well prior to carefully measuring out the dose.
• It may be given with or without food; however, if vomiting occurs when dosed on an empty stomach, give future doses with food.
• If your pet’s appetite is decreased, try hand-feeding favorite foods.
• Do not give this medication with aged cheeses.
• Do not stop giving this medication abruptly after long-term use or withdrawal can occur.

This medication can take a few weeks before full effects are noted, but gradual improvements are usually noticeable after a few days.

What if I miss giving my pet the medication?

If you miss a dose, give it as soon as you remember, and then continue with the regular dosing schedule. However, if it is almost time for the next dose, skip the missed dose and resume the regular dosing schedule. Do not give the pet two doses at once.

Are there any potential side effects?

Paroxetine may cause the following side effects:

• Sleepiness
• Decreased appetite
• Drooling
• Vomiting
• Diarrhea
• Constipation
• Difficulty urinating
• Muscle twitches
• Restlessness
• Sleeplessness
• Panting
• Dry/itchy skin
• Vocalization

Serious adverse reactions may occur. If any of the following signs develop, stop giving paroxetine and contact your veterinarian immediately:

• Seizures
• Aggressive behavior
• Hyperexcitability
• Persistent lack of appetite

Drug sensitivities can develop over time, with repeated exposure. Your pet may have no reaction after the first few doses but may develop a sensitivity later. It is important to watch for signs of an allergic reaction over the entire course of treatment.

Other side effects may occur. If you notice anything unusual, contact your veterinarian immediately. This moderate-acting medication should stop working in a few days, although effects can be longer in pets with liver or kidney disease.

Are there any risk factors for this medication?

DO NOT USE paroxetine should not be used in:

• Pets that are allergic to paroxetine or other SSRIs
• Pets currently taking monoamine oxidase inhibitors (MAOIs)

USE WITH CAUTION in:

• Pets with aggression
• Pets with seizures
• Pets with diabetes
• Pets with severe heart, liver, or kidney disease
• Pets that are pregnant, nursing, old, or sick

Do not stop this medication abruptly after long-term use or withdrawal can occur.

Are there any drug interactions I should be aware of?

The following medications should be used with caution when given with paroxetine:

• Alprazolam
• Beta-adrenergic blocking agents
• Buspirone
• Diazepam
• Diuretics
• Insulin
• Monoamine Oxidase Inhibitors (MAOIs; includes some flea/tick collars)
• Metoclopramide
• Mexiletine
• Moxifloxacin
• Nonsteroidal anti-inflammatory drugs (NSAIDs)
• Tramadol
• Trazodone
• Tricyclic antidepressants

Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking before starting any new treatment.

Is any monitoring needed with this medication?

• Your veterinarian will let you know when and how they want to reassess your pet to ensure the medication is working and not causing side effects.
• At home, monitor for any side effects such as those noted above. If any occur, stop using the medication and contact your veterinarian.

How do I store paroxetine?

• Store this medication at room temperature between 59°F and 86°F (15°C and 30°C).
• Store the liquid suspension below 77°F (25°C). Protect from direct sunlight.
• Keep the container out of reach of children and pets.

What should I do in case of emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility. Be prepared to provide information about the product and your pet's weight and symptoms.