Clomipramine

Overview

Clomipramine (Clomicalm®, Anafranil®) is a tricyclic antidepressant (TCA) used in veterinary behavioral medicine to manage anxiety-related disorders in dogs and cats. It is FDA-approved for use in dogs as part of a comprehensive behavior modification program for the treatment of separation anxiety, which may present as destructive behavior, excessive vocalization, or inappropriate elimination.

In veterinary practice, clomipramine is also used to manage a broader range of behavioral disorders, including compulsive behaviors, noise-related fears, and urine spraying in cats. Clinical improvement often requires several weeks of therapy, and treatment is typically combined with environmental management and behavioral modification techniques.

Mechanism of Action (MOA): Clomipramine acts primarily by inhibiting the reuptake of serotonin (5-HT) at the neuronal synapse, increasing serotonin availability in the central nervous system. Its active metabolite, desmethylclomipramine, mainly inhibits norepinephrine reuptake. The drug also interacts with histamine-1 receptors and blocks alpha-1 adrenergic and muscarinic cholinergic receptors, contributing to both its therapeutic and adverse effects.

Indications

Clomipramine is primarily used in dogs and cats for the management of behavioral and anxiety-related disorders. It is most effective when used together with appropriate behavior modification and environmental management.

• Separation anxiety (dogs): FDA-approved for the treatment of separation-related disorders when combined with a structured behavior modification program. Clinical signs may include destructive behavior, excessive vocalization, and inappropriate urination or defecation.
• Anxiety-related behavioral disorders: May be used to help manage various anxiety conditions such as generalized anxiety, noise phobias, and stress-related behaviors.
• Compulsive behaviors: Used in dogs and cats for compulsive or repetitive behaviors, including excessive licking, tail chasing, or other stereotypic behaviors.
• Urine spraying in cats: May be used extra-label to reduce urine marking behavior associated with stress or social conflict.
• Cataplexy in dogs: Clomipramine has been reported to improve signs of narcolepsy–cataplexy in dogs with long-term therapy.

Dosage (Reference)

Dog

In dogs, clomipramine is primarily used for behavioral disorders such as separation anxiety and compulsive behaviors. The medication is typically administered orally and used together with behavioral modification therapy.

Cat

In cats, clomipramine is used extra-label for behavioral disorders, particularly urine spraying and anxiety-related behaviors. Lower doses are typically used compared with dogs.

Warnings & Precautions

Clomipramine should be used cautiously in dogs and cats due to its effects on the central nervous system and autonomic pathways. Careful patient selection and monitoring are recommended, particularly in animals with pre-existing medical conditions or those receiving other medications that may interact with tricyclic antidepressants.

• Hypersensitivity: Clomipramine is contraindicated in animals with known hypersensitivity to clomipramine or other tricyclic antidepressants.
• Seizure disorders: The drug should not be used in animals with a history of seizures or in patients receiving medications that lower the seizure threshold.
• Monoamine oxidase inhibitors (MAOIs): Concomitant use with MAO inhibitors (e.g., selegiline or amitraz-containing products) is contraindicated. A minimum 14-day washout period should be allowed between therapies.
• Cardiovascular disease: Use cautiously in animals with cardiac disease or arrhythmias, as tricyclic antidepressants may affect cardiac conduction and rhythm.
• Hepatic disease: Because clomipramine is extensively metabolized in the liver, animals with pre-existing hepatic disease should receive the drug cautiously and may require monitoring.
• Anticholinergic effects: Due to its anticholinergic activity, use cautiously in animals with decreased gastrointestinal motility, urinary retention disorders, glaucoma, or increased intraocular pressure.
• Thyroid function: Clomipramine may decrease circulating thyroid hormone concentrations (tT3, tT4, and free T4). Baseline thyroid testing is recommended prior to initiating therapy.
• Discontinuation: Therapy should not be stopped abruptly. Gradual tapering is recommended to reduce the risk of withdrawal signs.
• Breeding animals: Use is contraindicated in breeding male dogs due to potential effects on fertility.

Drug Interactions

Clomipramine has numerous potential drug interactions because of its effects on serotonin, norepinephrine, cardiac conduction, and anticholinergic pathways. Careful review of concurrent medications is recommended before initiating therapy.

• Monoamine oxidase inhibitors (e.g., selegiline, amitraz products): Concurrent use is contraindicated due to the risk of severe serotonin syndrome. A washout period of at least 14 days is recommended between therapies.
• Selective serotonin reuptake inhibitors (e.g., fluoxetine, paroxetine, sertraline): Combination may increase the risk of serotonin syndrome. When switching from clomipramine to an SSRI, a washout period of several days is recommended.
• Other serotonergic drugs (e.g., tramadol, trazodone, buspirone, dextromethorphan): Concurrent use may increase the risk of serotonin syndrome and excessive CNS effects.
• CNS depressants (e.g., benzodiazepines, opioids, sedatives): Additive sedation and central nervous system depression may occur when used together.
• Anticholinergic drugs (e.g., atropine, glycopyrrolate, oxybutynin): Concurrent administration may increase anticholinergic effects such as tachycardia, constipation, urinary retention, and dry mouth.
• Sympathomimetic agents (e.g., ephedrine, phenylpropanolamine, albuterol): May increase the risk of cardiovascular stimulation including hypertension and cardiac arrhythmias.
• QT-prolonging medications (e.g., amiodarone, cisapride, quinidine, sotalol): Concurrent use may increase the risk of QT prolongation and cardiac arrhythmias.
• Barbiturates (e.g., phenobarbital): May reduce clomipramine effectiveness through increased hepatic metabolism.
• Cimetidine: May inhibit metabolism of tricyclic antidepressants and increase the risk of toxicity.

Side Effects & Overdose

Side Effects

Adverse effects associated with clomipramine are generally related to its central nervous system and anticholinergic properties. Some animals may experience mild gastrointestinal or behavioral changes during the early stages of treatment.

• Gastrointestinal signs: Vomiting, diarrhea, decreased appetite, and occasional constipation may occur.
• Sedation and lethargy: Drowsiness, reduced activity, or depression may develop, particularly during the initial phase of therapy.
• Anticholinergic effects: Dry mouth, tachycardia, urinary retention, mydriasis, and constipation may occur due to anticholinergic activity.
• Hepatic enzyme elevations: Mild increases in liver enzyme concentrations have been reported in some patients.
• Pancreatitis (rare): A case report has described pancreatitis developing in a dog receiving clomipramine.
• Increased sensitivity in cats: Cats may be more prone to adverse effects such as sedation, diarrhea, and anticholinergic signs.

Overdose

Clomipramine has a relatively narrow margin of safety, and overdose may result in serious neurologic and cardiovascular complications.

• Neurologic signs: Lethargy, agitation, tremors, ataxia, vocalization, and seizures may occur.
• Cardiovascular effects: Tachycardia, arrhythmias, and conduction abnormalities may develop.
• Autonomic signs: Mydriasis, vomiting, and central nervous system depression may be observed.
• Management: Treatment includes supportive care and appropriate gastrointestinal decontamination when indicated.
• Severe toxicity: Life-threatening complications such as seizures, cardiac arrhythmias, and cardiorespiratory collapse may occur at high doses.

Key Notes

Practical clinical considerations that may help optimize the use of clomipramine in dogs and cats when managing behavioral disorders:

• Behavioral therapy is essential: Clomipramine should always be used alongside a structured behavior modification program to achieve the best clinical outcomes.
• Active metabolite contribution: The drug is metabolized to desmethylclomipramine, an active metabolite that contributes significantly to its overall pharmacologic effects.
• Slower metabolism in cats: Cats tend to metabolize clomipramine more slowly than dogs, which can lead to greater variability in drug response between patients.
• Baseline diagnostic evaluation recommended: Prior to starting therapy, baseline bloodwork (CBC, serum chemistry, urinalysis) and thyroid testing are commonly recommended to help monitor patient safety during treatment.
• ECG monitoring consideration: Baseline electrocardiography may be advisable in some patients because tricyclic antidepressants can influence cardiac conduction.
• Drug name confusion risk: Care should be taken not to confuse clomiPRAMINE with chlorproMAZINE, as the two medications have very different pharmacologic effects.