Nurses Compass
Drug Guide
Imipramine Hydrochloride
Classification
Therapeutic: Antidepressant, Tricyclic
Pharmacological: Tricyclic Antidepressant (TCA)
FDA Approved Indications
- Major depressive disorder
- Enuresis (bedwetting) in children over 6 years
Mechanism of Action
Inhibits reuptake of norepinephrine and serotonin in the central nervous system, increasing their availability in synaptic clefts.
Dosage and Administration
Adult: Initial dose 75 mg per day in divided doses; dosage may be titrated based on response and tolerability.
Pediatric: For enuresis, typical dose ranges from 10-25 mg at bedtime; adjustment based on response.
Geriatric: Start at lower doses (e.g., 25-50 mg at bedtime) due to increased sensitivity and risk of side effects.
Renal Impairment: Adjust dose based on clinical response, monitor closely.
Hepatic Impairment: Use with caution; start at lower doses, monitor liver function.
Pharmacokinetics
Absorption: Well absorbed orally.
Distribution: Wide distribution, crosses the blood-brain barrier.
Metabolism: Primarily hepatic conjugation and oxidative metabolism via CYP2D6, CYP1A2, CYP3A4.
Excretion: Renal elimination of metabolites.
Half Life: Approximately 8-16 hours, variable.
Contraindications
- Recent myocardial infarction
- Concomitant use of MAO inhibitors
- Known hypersensitivity to TCAs
Precautions
- History of seizure disorders, angle-closure glaucoma, urinary retention, hepatic impairment, bipolar disorder (risk of manic episodes).
- Pregnancy category C; lactation may pass into breast milk.
Adverse Reactions - Common
- Dry mouth (Common)
- Drowsiness (Common)
- Dizziness (Common)
- Constipation (Common)
Adverse Reactions - Serious
- Myocardial infarction (Rare)
- Suicidal thoughts (Monitor closely, especially in young adults and adolescents)
- Serotonin syndrome (Rare, especially when combined with other serotonergic drugs)
Drug-Drug Interactions
- Monoamine oxidase inhibitors (risk of serotonin syndrome), other CNS depressants, anticholinergic agents, sympathomimetics.
- QT prolongation drugs
Drug-Food Interactions
- Avoid alcohol and CNS depressants.
Drug-Herb Interactions
- St. John's Wort may increase serotonergic effects and risk of serotonin syndrome.
Nursing Implications
Assessment: Monitor mental status, suicidal thoughts, ECG for QT interval prolongation, blood pressure, and signs of anticholinergic effects.
Diagnoses:
- Risk for suicide, risk for imbalanced fluid volume, activity intolerance.
Implementation: Administer at bedtime to minimize drowsiness. Regularly assess for side effects and therapeutic response.
Evaluation: Evaluate for improvement in depression symptoms or enuresis control, and monitor for adverse effects.
Patient/Family Teaching
- Take medication exactly as prescribed, do not discontinue abruptly.
- Warn about potential side effects such as dry mouth, drowsiness, dizziness.
- Caution about alcohol and other CNS depressants.
- Report worsening depression or emergence of suicidal thoughts.
- Avoid driving or complex tasks until response is known.
Special Considerations
Black Box Warnings:
- Increased risk of suicidal thinking and behavior in children, adolescents, and young adults.
- Use with caution in cardiac patients due to potential for arrhythmias.
Genetic Factors: Metabolism affected by CYP2D6 polymorphisms, influencing drug levels.
Lab Test Interference: May interfere with certain lab tests, including serum glucose and thyroid function.
Overdose Management
Signs/Symptoms: Drowsiness, confusion, agitation, hallucinations, seizures, cardiac arrhythmias, hypotension.
Treatment: Supportive care, activated charcoal, sodium bicarbonate for cardiac toxicity, vasopressors for hypotension, lidocaine or magnesium for arrhythmias, cardiopulmonary resuscitation as needed.
Storage and Handling
Storage: Store at room temperature, protected from humidity and light.
Stability: Stable under normal storage conditions for prescribed duration.