BUSPIRONE HYDROCHLORIDE

(for veterinary information only)

BRAND NAME: BUSPAR

AVAILABLE IN
5 mg, 7.5 mg, 10 mg, 15 mg, 30 mg
TABLETS

BACKGROUND

The relief of anxiety is an area of human medicine which has received a great deal of pharmaceutical attention. In the beginning, there were only tranquilizers, such as diazepam, which were helpful but also addictive and had undesirable drowsiness side effects. The development of non-addictive non-sedating medications to relieve anxiety (called anxiolytic drugs) has been an important area of pharmacology in the last 20 years. The development of buspirone, a member of the azapirone class of anxiolytics, stems from this research. Buspirone is able to relieve anxiety with minimal sedation, minimal muscle relaxation, and no addiction potential.

In veterinary medicine, buspirone has been especially helpful in the treatment of stress-related urine marking in cats. Prior to the use of diazepam as mentioned, strong female hormones (progestins) had been the favored treatment. Happily, diazepam was free from the unpleasant side effects of hormone therapy but, unfortunately, the problem behavior typically returned when the diazepam was discontinued. When buspirone was used, a sustained effect was seen such that after an eight week course, medication could be discontinued, in many cases permanently, without recurrence of urine marking. 

HOW THIS MEDICATION IS USED

Buspirone requires several weeks of administration to achieve effectiveness. Single doses would not be expected to be effective. It is not a helpful drug for panic-like syndromes (like thunderstorm phobias) either in humans or in animals but is effective for more generalized anxiety. As mentioned, the usual use is for urine-marking in cats but can also be used to relieve anxiety in timid cats who are bullied by more dominant cats.

Buspirone is usually given 2-3 times daily. Buspirone can be given with or without food.

If a dose is skipped accidentally, do not double up on the next dose. Simply give the next dose at the regular time.

SIDE EFFECTS

The most commonly observed side effect with this medication is an increase in affectionate behavior in the cat. This may not sound problematic but some owners complain of not being able to sleep through the aggressive purring and rubbing. Any drug that modifies behavior has potential to reduce a cat’s inhibitions thus making other behavioral changes, including aggression, possible.

Side effects that have been reported by humans taking buspirone include: nausea, headache, dizziness, appetite loss, and restlessness.

Increases in heart rate have been an occasionally noted side effect in humans though it is usually reduced heart rate that is seen in cats.

INTERACTIONS WITH OTHER DRUGS

Buspirone should not be used in conjunction with monoamine oxidase inhibitors such as Deprenyl, a medication mostly used against canine cognitive dysfunction, or Amitraz, a tick-killing ingredient common in many flea and tick products. Dangerous episodes of high blood pressure ("serotonin syndrome") can result when these medications are used in conjunction. Anther medication that can increase the risk of serotonin syndrome include mirtazapine (an appetite stimulant).

Concurrent use of buspirone with sedating medications (antihistamines, certain pain relievers, tranquilizing anti-anxiety medications) will have increased potential to cause sedation.

The following medications can increase the blood levels of buspirone thus increasing the potential for side effects:

• Diltiazem (a heart medication)
• Erythromycin (an antibiotic)
• Ketoconazole (an antifungal)
• Itraconazole (an antifungal)
• Cimetidine (an antacid)

 A serious drop in blood pressure can result when buspirone is combined with medications that treat hypertension, including diuretics. A similar reaction can occur when buspirone is combined with either prazosin or phenoxybenzamine.

Buspirone should not be used with metoclopramide (neurologic reactions).

CONCERNS AND CAUTIONS

• Buspirone tablets should be stored in a way that protects them from light exposure.
• This medication should be used cautiously in patients with either liver or kidney disease.
• Buspirone has not been shown to be safe for use in pregnancy. It definitely crosses into the mammary gland and can be passed to nursing young.

Page last updated: 3/16/2023