What are the contraindications to doxepin (tricyclic antidepressant)?

Contraindications to Doxepin

Doxepin is contraindicated in individuals with hypersensitivity to the drug, in patients with glaucoma or a tendency to urinary retention, and should not be used concomitantly with monoamine oxidase inhibitors (MAOIs). 1

Absolute Contraindications

• Hypersensitivity to doxepin: Patients who have shown hypersensitivity to doxepin should not receive the medication. Cross-sensitivity with other dibenzoxepines should be considered 1
• Glaucoma: Doxepin is contraindicated in patients with glaucoma due to its anticholinergic effects 1
• Urinary retention: Patients with a tendency toward urinary retention should not use doxepin 1
• Concurrent use with MAOIs: Similar to other tricyclic antidepressants, doxepin should not be used in combination with monoamine oxidase inhibitors 2

Relative Contraindications and Precautions

Psychiatric Considerations

• Suicidal ideation risk: Increased risk of suicidal thinking and behavior in children, adolescents, and young adults (ages 18-24) with major depressive disorder and other psychiatric disorders 1
• Bipolar disorder: Should be used with caution as it may precipitate a manic episode in patients with bipolar disorder

Age-Related Considerations

• Pediatric patients: Not recommended for use in children under 12 years due to lack of clinical experience in this population 1
• Elderly patients: Should be used with caution due to increased risk of:
  • Cognitive decline 3
  • Confusion 3
  • Falls 3

Medical Conditions

• Cardiovascular disease: While doxepin causes fewer cardiovascular side effects at therapeutic doses compared to some other tricyclics, it has intrinsic cardiotoxicity on overdosage similar to other tricyclic antidepressants 4
• Sleep apnea: May worsen sleep apnea and should be used with caution in these patients 2
• Neurodegenerative disorders: Should be used with caution due to increased risk of confusion and falls 2
• Seizure disorders: May lower the seizure threshold
• Hepatic or renal impairment: May require dosage adjustments

Special Populations

• Pregnancy: Contraindicated in women who are or may become pregnant 3
• Breastfeeding: Should be used with caution as it may be excreted in breast milk

Monitoring Considerations

• Baseline assessment: Rule out glaucoma and urinary retention, particularly in older patients 1
• Suicidality monitoring: Close observation for clinical worsening, suicidality, or unusual changes in behavior, particularly during the initial few months of therapy or at times of dose changes 1
• Cardiovascular monitoring: Consider baseline and periodic ECG monitoring in patients with pre-existing cardiovascular disease

Drug Interactions

• MAOIs: Contraindicated due to risk of serotonin syndrome 2
• CNS depressants: Additive effects with alcohol, sedatives, and other CNS depressants
• Anticholinergic medications: Additive anticholinergic effects
• Guanethidine: At dosages above 150 mg per day, doxepin may block the antihypertensive effect of guanethidine and related compounds 1

Side Effect Profile to Consider

• Common side effects: Dry mouth, drowsiness, constipation 4
• Neuropsychiatric effects: Sedation, confusion, cognitive impairment 3
• Anticholinergic effects: Blurred vision, dry mouth, constipation, urinary retention
• Cardiovascular effects: Postural hypotension (uncommon at therapeutic doses) 4
• Increased risk of suicidal thoughts: Particularly in children, adolescents, and young adults 1

Despite these contraindications and precautions, doxepin has shown efficacy in treating insomnia in various populations, including those with Parkinson's disease 5, and has been found effective at low doses (3-6 mg) for insomnia with minimal next-day residual effects 6, 7.