Asendin (amoxapine) is a tetracyclic antidepressant indicated for the treatment of major depressive disorder. It functions primarily as a norepinephrine reuptake inhibitor and also exhibits secondary dopamine receptor blockade. This dual mechanism provides a distinct therapeutic profile, offering robust antidepressant efficacy with a potentially favorable side effect constellation for appropriate patient populations. Clinical use requires careful patient selection and monitoring due to its specific pharmacological actions.

Features

• Active ingredient: Amoxapine
• Therapeutic class: Tetracyclic antidepressant
• Available in 25 mg, 50 mg, 100 mg, and 150 mg oral tablets
• Bioavailability: Approximately 90% following oral administration
• Half-life: 8 hours for amoxapine; active metabolite 7-hydroxyamoxapine has 30-hour half-life
• Metabolism: Hepatic, primarily via CYP2D6 isoenzyme
• Excretion: Renal (60%) and fecal (30%)

Benefits

• Provides rapid onset of antidepressant action, often within 4-7 days
• Effective for both emotional and somatic symptoms of depression
• Lower incidence of anticholinergic side effects compared to traditional tricyclics
• May improve sleep architecture and reduce anxiety symptoms
• Suitable for patients with treatment-resistant depression
• Cost-effective alternative to newer antidepressants

Common use

Asendin is primarily prescribed for the management of major depressive disorder in adults. It may be particularly beneficial for patients who have not responded adequately to SSRIs or other first-line antidepressants. Off-label uses include adjunctive treatment for neuropathic pain and management of certain anxiety disorders, though robust evidence for these indications is limited. The medication is typically incorporated into a comprehensive treatment plan that may include psychotherapy and lifestyle modifications.

Dosage and direction

Initial dosage: 25 mg two or three times daily, titrated gradually based on tolerance and therapeutic response. Maintenance dosage: Typically 100-300 mg daily in divided doses, not to exceed 400 mg daily in outpatient settings or 600 mg daily in hospitalized patients. Elderly patients and those with hepatic impairment should start at lower doses (25-50 mg daily). Tablets should be swallowed whole with water, with or without food, though consistent administration with meals may reduce gastrointestinal discomfort. Therapeutic effects may take 2-4 weeks to become fully apparent despite earlier symptom improvement.

Precautions

Regular monitoring of blood pressure and heart rate is recommended, especially during dose titration. Periodic liver function tests and complete blood counts are advised during prolonged therapy. Use with caution in patients with cardiovascular disease, glaucoma, prostate hypertrophy, or thyroid disorders. May impair mental or physical abilities required for hazardous tasks; patients should avoid alcohol consumption. Abrupt discontinuation should be avoided; taper gradually over 2-4 weeks to prevent withdrawal symptoms.

Contraindications

Hypersensitivity to amoxapine or any tetracyclic antidepressants. Concurrent use with MAO inhibitors or within 14 days of discontinuing MAO inhibitor therapy. Acute recovery phase following myocardial infarction. Severe liver impairment. Untreated narrow-angle glaucoma. History of seizures or epilepsy. Pregnancy unless potential benefits outweigh risks (Category C).

Possible side effects

Common (≥10%): Dry mouth, drowsiness, constipation, blurred vision. Less common (1-10%): Dizziness, headache, nausea, weight changes, sweating. Rare (<1%): Extrapyramidal symptoms, tardive dyskinesia (particularly with long-term use), neuroleptic malignant syndrome, seizures, cardiac arrhythmias, jaundice, blood dyscrasias. Most side effects are dose-dependent and may diminish with continued therapy.

Drug interaction

MAO inhibitors: Risk of serotonin syndrome and hypertensive crisis. CNS depressants: Enhanced sedative effects. Anticholinergic agents: Additive adverse effects. CYP2D6 inhibitors (fluoxetine, paroxetine): Increased amoxapine levels. Antihypertensives: Potential reduced efficacy. Sympathomimetics: Enhanced pressor effects. Warfarin: Possible altered anticoagulant effect. Always review complete medication profile before initiation.

Missed dose

If a dose is missed, take it as soon as remembered unless it is nearly time for the next dose. Do not double doses to make up for missed administration. Maintain regular dosing schedule to ensure stable plasma concentrations. Patients should contact their healthcare provider if multiple doses are missed to discuss appropriate management strategy.

Overdose

Symptoms may include severe drowsiness, confusion, seizures, cardiac arrhythmias, hypotension, and coma. Management requires immediate medical attention. Gastric lavage may be beneficial if performed within 1-2 hours of ingestion. Activated charcoal may be administered. Supportive care includes maintaining airway, monitoring cardiac function, and managing seizures with benzodiazepines. There is no specific antidote; treatment is symptomatic and supportive.

Storage

Store at controlled room temperature (20-25°C/68-77°F) in original container. Protect from light and moisture. Keep tightly closed and out of reach of children. Do not use after expiration date printed on packaging. Properly dispose of unused medication through take-back programs or according to FDA guidelines.

Disclaimer

This information is for educational purposes only and does not constitute medical advice. Asendin is available by prescription only and should be used under appropriate medical supervision. Individual response to medication may vary. Healthcare providers should review full prescribing information before initiating therapy. Patients should not adjust dosage or discontinue medication without consulting their physician.

Reviews

Clinical studies demonstrate response rates of 60-70% in patients with major depressive disorder. Many clinicians report particular efficacy in patients with melancholic features and psychomotor retardation. Long-term users often note sustained efficacy with stable dosing. Some patients report preference over SSRIs due to less sexual dysfunction and emotional blunting. However, individual experiences vary significantly, and careful patient selection remains crucial for optimal outcomes.