Imipramine

Overview

What is Imipramine?

Imipramine is a medication belonging to the tricyclic antidepressant (TCA) class. The drug is believed to act inhibiting the reuptake of norepinephrine and serotonin at nerve endings for the relief of symptoms of depression. It is also used as an adjunctive therapy for bedwetting in children, and its efficacy in childhood enuresis is independent of its antidepressant effect.

Global Name

• Generic names: Imipramine hydrochloride, Imipramine pamoate
• Brand names: Tofranil and Tofranil-PM

Usage

What is Imipramine used for?

• Depression: For the relief of symptoms of depression. 

• Childhood Enuresis (Bedwetting): Tofranil is indicated as temporary adjunctive therapy in reducing nocturnal enuresis in children aged 6 years and older, after excluding organic causes. (Note: Tofranil-PM  is not indicated for the treatment of childhood enuresis.)

How do you use Imipramine?

Dosage form:

• Tablets: 10 mg, 25 mg, 50 mg

• Capsules: Not available in Hong Kong. Extended-release formulations in strength of 75 mg, 100 mg, 125 mg, 150 mg

Dosage information: The following recommended dosages should be modified as necessary by the clinical response and any evidence of intolerance.

• Depression
  • Tofranil (Imipramine hydrochloride)
    • Outpatients: 75 mg/day increased to 150 mg/day.
    • Hospitalised patients: 100 mg/day in divided doses gradually increased to 200 mg/day as required.
    • Adolescents and geriatric patients: 30 to 40 mg/day.
  • Tofranil-PM (Imipramine pamoate)
    • Outpatients: 75 mg/day increased to 150 mg/day.
    • Hospitalised patients: 100 to 150 mg/day and may be increased to 200 mg/day.
    • Adult (Maintenance): The usual maintenance dosage is 75 to 150 mg/day.
    • Adolescent and Geriatric Patients: Used only when the total daily dosage is established at 75 mg or higher.
• Childhood Enuresis
  • A common starting dose is 25 mg/day given one hour before bedtime. If necessary, this may be increased to 50 mg (for children under 12) or 75 mg (for children over 12). The dose should not exceed 2.5 mg/kg/day.
    

• Pregnant women: May be used only if the clinical condition clearly justifies potential risk to the fetus.
• Nursing mothers: Not suitable as imipramine hydrochloride tablets are likely to be excreted in human breast milk.
• Paediatric patients: Not suitable for children under 6 years old.
• Geriatric patients: Be cautious with the dose selection for the elderly and start at the lower dosage.
• Patients with significantly impaired renal or hepatic function: use with caution 

Warnings and precautions:

• Clinical Worsening and Suicide Risk: Patients with major depressive disorder, both adult and pediatric, may experience worsening of their depression and/or the emergence of suicidal ideation and behavior (suicidality) or unusual changes in behavior especially during the early phase/months of treatment.

• Cardiac Health: Extreme caution is required in patients with cardiovascular disease because of cardiovascular toxicity.

• Risk of bipolar disorder: Treating a major depressive episode with an antidepressant alone may increase the likelihood of precipitation of a mixed/manic episode in patients at risk for bipolar disorder.

• Serotonin Syndrome: A potentially life-threatening condition may occur, particularly when used with other serotonergic drugs or taken with food high in serotonin content such as cheese and banana.

• Seizures: Imipramine may lower the seizure threshold; use with caution in patients with a history of seizure disorders.

Precautions:

• An ECG recording should be taken before starting higher doses.

• Elderly patients and patients with cardiac disease or a prior history of cardiac disease are at risk of developing cardiac abnormalities.

• Carefully supervise seriously depressed patients.

• Hypomanic or manic episodes may occur.

• An activation of  psychosis may occasionally be observed in schizophrenic patients.

• Concurrent administration of imipramine pamoate with electroshock therapy may increase the hazards.

• Avoid excessive exposure to sunlight.

• Monitor blood sugar level. 

Interactions and contraindications of the drug:

• Drug interactions: Imipramine interacts with drugs metabolized by P450 2D6, hepatic enzyme inducers and inhibitors, anticholinergic drugs, and sympathomimetic amines.

• Contraindications: Do not use imipramine during the acute recovery period after a myocardial infarction, in patients with known hypersensitivity to the drug, or in patients taking MAOIs or within 14 days of discontinuing MAOIs.

Side Effects

Common side effects may include:

• Dry mouth
• Drowsiness, dizziness, or blurred vision 
• Constipation and urinary retention
• Weight gain or loss
• Nausea and vomiting
• Palpitations 

Common side effects in enuretic children:

• Nervousness

   

• Sleep disorders 

   

• Tiredness 

   

• Mild gastrointestinal disturbances
  
  

Pharmacist Tips

• Storage information: Store at 20° to 25°C (68° to 77°F). Dispense in tight container with a child-resistant closure. 

• Administration: Tofranil (Imipramine hydrochloride) and Tofranil-PM (Imipramine pamoate) are orally administered. 

Availability

Where is imipramine available in Hong Kong?

In Hong Kong, imipramine hydrochloride is classified as a prescription only medicine. It can be obtained from a registered pharmacy with a doctor's prescription or directly from a doctor.

FAQs

What is imipramine hydrochloride?

Imipramine hydrochloride is a tricyclic antidepressant used mainly to treat depression. In Hong Kong, it is available under the brand name Tofranil.

How long does it take for imipramine to work?

It may take 1 to 3 weeks or longer before you notice an improvement in your symptoms of depression. For bedwetting, a response is often seen within the first week. 

Can I take imipramine during pregnancy?

Imipramine should be used during pregnancy only if the potential benefit justifies the potential risk to the foetus. Please consult your doctor for more information. 

How much does imipramine cost?

Imipramine is a prescription-only medicine, and the price varies depending on the healthcare provider.