Imipramine

What is imipramine?

Imipramine (brand names: Tofranil®, Impril®) is a tricyclic antidepressant used to treat urinary incontinence, sudden muscle weakness, and certain behavior disorders. It may also be used in conjunction with other medications to treat chronic pain. In horses, it has been used for narcolepsy and ejaculatory dysfunction.

Its use in cats, dogs, and horses to treat behavior and medical conditions 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 imipramine given?

• Imipramine is given by mouth in the form of a tablet or capsule. It may also be compounded into an oral liquid to be given by mouth or injectable liquid to be used in the clinic.
• It may be given with or without food; however, if vomiting occurs when dosed on an empty stomach, give future doses with food.
• Measure liquid forms carefully.
• Do not give this medication in conjunction with aged cheese or while using amitraz-containing flea/tick collars.
• Allow free access to water while giving this medication.

This medication can take up to a few weeks before full effects are noted, and at times improvement may not be visible; Laboratory tests may be needed to evaluate this medication’s effectiveness.

What if I miss giving my pet the medication?

If you miss giving your pet a dose, give the next dose as soon as you remember. However, if it is less than 12 hours until the next scheduled dose, either:

• skip the dose you missed, give it at the next scheduled time, and continue with the regular dosing schedule OR
• give the missed dose and then wait the recommended interval before giving the next dose (continue giving it regularly at that new time).

Are there any potential side effects?

Studies are limited for this medication, so information about side effects is also limited. However, common side effects are typically like other tricyclic antidepressants and include:

• Sleepiness
• Dry mouth
• Constipation
• Diarrhea (less common)
• Vomiting (less common)
• Trouble urinating (less common)

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

• Excitability
• Shaking
• Seizures
• Bleeding
• Fever
• Fast heartbeat
• Weakness
• Collapse

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 imipramine in pets that:

• Are allergic to it or other tricyclic antidepressants
• Are also taking monoamine oxidase inhibitors (MAOIs)
• Are pregnant or nursing

USE WITH CAUTION in pets that:

• Are very young or old,
• Have seizures, diabetes, adrenal gland problems, glaucoma, or dry eye syndrome (KCS)
• Have liver, thyroid, or heart disease

Are there any drug interactions I should be aware of?

Several medications should be used with caution when given with imipramine, including:

• Alprazolam
• Anticholinergic agents
• Cisapride
• Clonidine
• Central nervous system (CNS) depressants
• Cyclobenzaprine
• Monoamine oxidase inhibitors (MAOIs)
• Metoclopramide
• Nonsteroidal antiinflammatory drugs (NSAIDs)
• Opioids
• Phenobarbital
• Phenothiazines
• Selective serotonin reuptake inhibitor (SSRIs)
• Thyroid agents
• Tramadol

Imipramine may also interact with blood glucose testing. 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 imipramine?

• Store the tablets and capsules at room temperature and protect from light.
• Store compounded forms of this medication according to the label.
• 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.