Mar Vista Animal Medical Center

3850 Grand View Blvd.
Los Angeles, CA 90066

(310)391-6741

marvistavet.com

FLUOXETINE

(for veterinary information only)

 

BRAND NAME: RECONCILE, PROZAC

 

AVAILABLE IN
10, 15 and 20 mg TABLETS,
10 mg, 20 mg, 40 mg and 90 mg CAPSULES,
ORAL LIQUID,
AND
8 mg, 16 mg, 32 mg, 64 mg
CHEWABLE TABLETS
FOR DOGS.

BACKGROUND

Anxiety, obsessive-compulsive disorder, and depression are common problems for humans. Because the development of drugs that alleviate these conditions is ongoing, there are many medications on the market for these uses currently. One of the more popular classes of anti-anxiety medications are the “selective serotonin reuptake inhibitors” also called “SSRI”’s for short.

Serotonin is a neurotransmitter in the brain associated among other things with mood elevation and reduced aggression. Increasing serotonin in the brain means less anxiety and a happier attitude. By inhibiting the brain’s system for removing used serotonin, SSRI’s cause serotonin to linger, lasting longer. The more serotonin we have in our brains, the less anxiety, obsession, and depression we get.

Eli Lilly, a prominent pharmaceutical company, tested many related compounds and released fluoxetine as the most specific “selective serotonin reuptake inhibitor” of all of them. Fluoxetine, marketed under the brand name Prozac®, was not quite the first SSRI on the human market but quickly became the most popular.


Serotonin: a neurotransmitter that makes us happy
(Photocredit: Public Domain image via Wikimedia Commons)

It was not long after that that fluoxetine found its way into veterinary use for animals with anxiety, compulsive behavior, and other behavior issues. When low-cost generic fluoxetine became available, its use increased in the veterinary market and in 2007 Eli Lilly released a version of fluoxetine specifically labeled for animal use.

HOW THIS MEDICATION IS USED

Fluoxetine has been used in many animal behavior issues: inappropriate urine marking in both dogs and cats, separation anxiety, compulsive chewing, circling, and self-mutilation, even aggression. Eli Lilly released a product approved for dogs (Reconcile®) in 2007. This product is specifically approved for the treatment of separation anxiety.

It should be noted that the treatment of behavior disorders requires training in addition to simply giving the pet a medication. In the instance of separation anxiety, Lilly has trademarked the B.O.N.D. training program (for details visit www.reconcile.com). Our on-line web library also has information (see link above). When medication and treatment were combined, 42% of dogs with separation anxiety showed improvement by the end of the first week and 73% were improved within 8 weeks.

Fluoxetine is usually given once daily.

 

SIDE EFFECTS

It is important to understand that whenever an anti-anxiety medication is used, the phenomenon of “disinhibition” is possible. What this means is that an animal’s inhibitions about aggressive behavior may be reduced when his or her anxiety over the consequences of such behavior is removed. An animal that was not previously aggressive could potentially become aggressive.

The most common side effect of fluoxetine use is drowsiness or lethargy, but the opposite is also reported: hyperactivity, panting (dogs), and/or insomnia. Appetite reduction has also been described.

Appetite reduction is a common side effect of fluoxetine in the dog. Approximately 22% of the dogs in the Reconcile® licensing studies showed 5-10% weight loss on this medication while 6% showed 10-15% weight loss. In other words, these dogs lost 5-10% or 10-15% of the initial body weight while taking fluoxetine.

Some patients will experience an upset stomach with this medication.

 

INTERACTIONS WITH OTHER DRUGS

Serotonin syndrome is a potentially dangerous situation that can result when serotonin levels get too high.  Elevated heart rate, tremors/shivering, dilated pupils, difficulty breathing, elevated body temperature, hyperactivity, and/or high blood pressure can all be signs of serotonin syndrome. Fortunately, the development serotonin syndrome generally requires a combination of at least two serotonin-increasing drugs and rarely happens spontaneously with one medication but it is important to be aware of the symptoms as the high blood pressure can be life-threatening if severe enough.  Using MAO inhibitors in conjunction with fluoxetine could create serotonin syndrome. MAO inhibitors are rarely used in veterinary patients with the exception of seligiline, a drug used for cognitive dysfunction in dogs, and amitraz, an anti-parasite topical which is used in several tick control products (see our tick product comparison chart) as well as in Mitaban® dip which is used against mange. Fluoxetine should not be given in conjunction with a Monoamine oxide inhibitor (“MAO inhibitor”) such as seligiline or amitraz.

The use of buspirone, tramadol, clomipramine, or amitriptyline with fluoxetine can also increase the risk of serotonin syndrome.

Cyproheptadine, an appetite stimulant, may decrease or even reverse the effect of fluoxetine.

Diazepam and alprazolam may have stronger effects if used in conjunction with fluoxetine.

Fluoxetine should not be used in combination with drugs that could increase the likelihood of seizures (such as acepromazine).

Insulin requirements may be altered in the presence of fluoxetine.

 

CONCERNS AND CAUTIONS

This medication is best not used in patients with diabetes mellitus or with seizure disorders.

Page posted: 1/29/2016