Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ASENDIN vs AMITRIPTYLINE HYDROCHLORIDE
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Amoxapine, a dibenzoxazepine tricyclic antidepressant, primarily inhibits the reuptake of norepinephrine and serotonin. Its metabolite, 7-hydroxyamoxapine, exhibits dopamine D2 receptor antagonism, contributing to its antipsychotic effects.
Inhibits reuptake of serotonin and norepinephrine, leading to increased concentrations at synaptic cleft; also blocks histamine H1, alpha-1 adrenergic, and muscarinic cholinergic receptors.
Treatment of depression (neurotic and psychotic depression),Off-label: anxiety disorders, agitation in schizophrenia
Major depressive disorder,Neuropathic pain,Fibromyalgia,Migraine prophylaxis,Chronic tension-type headache,Insomnia (off-label),Irritable bowel syndrome (off-label)
50 mg orally three times daily, increased gradually to 100-200 mg/day in divided doses. Max 300 mg/day.
Oral: 25-150 mg daily in divided doses or as a single bedtime dose; maximum 300 mg/day.
Terminal elimination half-life is approximately 24-30 hours. Clinical context: Steady-state is reached within 5-7 days; the half-life supports once-daily dosing in most patients.
Terminal elimination half-life is 15-35 hours (range 9-46 hours); clinical context: steady-state concentrations achieved within 7-10 days; may be prolonged in elderly, hepatic impairment, or CYP2D6 poor metabolizers.
Primarily hepatic via CYP450 enzymes, notably CYP2D6 and CYP3A4. Major metabolites: 7-hydroxyamoxapine (active) and 8-hydroxyamoxapine.
Primarily hepatic via CYP2D6, CYP3A4, CYP1A2, and CYP2C19; active metabolite nortriptyline; undergoes demethylation, hydroxylation, and conjugation.
Renal (approximately 50% as unchanged drug and metabolites), biliary/fecal (30-40%), with the remainder as other metabolites; <10% excreted unchanged in urine.
Primarily renal (approximately 30-50% as unchanged drug and metabolites, mainly glucuronide conjugates and hydroxylated metabolites). Fecal excretion accounts for <5%. Enterohepatic recirculation may occur.
90-95% bound to plasma proteins, primarily albumin and alpha-1-acid glycoprotein.
Approximately 94-96%; primarily bound to alpha-1-acid glycoprotein (AAG), with minor binding to albumin and lipoproteins.
Apparent volume of distribution is 8-10 L/kg, indicating extensive tissue distribution and accumulation in peripheral compartments.
10-20 L/kg (large Vd due to extensive tissue binding); clinical meaning: high tissue penetration, especially CNS, and slow redistribution from tissues.
Oral bioavailability is approximately 70-80% due to first-pass metabolism. No parenteral formulation is available; only oral route.
Oral: 30-60% due to extensive first-pass metabolism (CYP2C19, CYP3A4, CYP2D6); significant interindividual variability.
Cr Cl 30-60 m L/min: reduce dose by 25-50%. Cr Cl <30 m L/min: contraindicated.
GFR 10-50 m L/min: use 50% of normal dose; GFR <10 m L/min: use 25% of normal dose.
Child-Pugh class C: contraindicated. Child-Pugh class B: reduce dose by 50%.
Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: avoid use.
Not recommended for use in children due to lack of safety data.
Adolescents: 10-50 mg daily in divided doses; children under 12 years (for enuresis): 6-10 years: 10-20 mg, 11+ years: 25-50 mg at bedtime.
Initial dose 25 mg twice daily, increase slowly with close monitoring due to increased sensitivity and anticholinergic effects.
Start at 10-25 mg at bedtime; increase by 10-25 mg every 3-7 days as tolerated; maximum 75-100 mg daily; monitor for CNS and anticholinergic effects.
Increased risk of suicidal thinking and behavior in children, adolescents, and young adults with major depressive disorder and other psychiatric disorders.
Increased risk of suicidal thinking and behavior in children, adolescents, and young adults taking antidepressants. Close monitoring for clinical worsening, suicidality, or unusual changes in behavior is recommended.
Suicidality risk,Neuroleptic malignant syndrome,Tardive dyskinesia,Seizure threshold lowering,Cardiotoxicity (QT prolongation, arrhythmias),Anticholinergic effects,Hypotension,Hepatic impairment
Cardiotoxicity (QT prolongation, arrhythmias), serotonin syndrome, activation of mania/hypomania, angle-closure glaucoma, urinary retention, seizures, increased intraocular pressure, orthostatic hypotension, drowsiness, withdrawal symptoms upon abrupt discontinuation.
Hypersensitivity to amoxapine or any component,Concomitant use with MAOIs or within 14 days of MAOI discontinuation,Acute recovery phase after myocardial infarction,Known alcohol or barbiturate intoxication
Concurrent use with MAOIs (risk of serotonin syndrome), recent myocardial infarction, hypersensitivity to tricyclic antidepressants, during acute recovery phase of MI, use with cisapride or other QT-prolonging drugs.
Avoid ethanol; may cause additive CNS depression. No specific food interactions; however, taking with food may reduce GI upset.
Avoid alcohol and tyramine-rich foods (e.g., aged cheese, cured meats, soy sauce) due to risk of hypertensive crisis. Limit caffeine intake; may increase CNS stimulation. Grapefruit juice may increase plasma levels; avoid or limit consumption.
ASENDIN (amoxapine) is classified as FDA Pregnancy Category C. First trimester: Limited human data; animal studies show fetal toxicity at high doses. Risk of congenital malformations cannot be excluded. Second and third trimesters: Neonates may exhibit transient withdrawal symptoms (jitteriness, respiratory depression) or serotonin syndrome if used near term. Avoid use unless benefit outweighs risk.
First trimester: Limited data suggest a small increased risk of congenital malformations, particularly cardiovascular defects. Second trimester: No specific malformation risk, but possible effects on fetal growth. Third trimester: Risk of neonatal withdrawal syndrome (irritability, feeding difficulties) and anticholinergic effects (constipation, urinary retention). Overall risk is low; benefits may outweigh risks in severe depression.
Amoxapine is excreted in human breast milk. M/P ratio is unknown. Due to limited safety data, breastfeeding is not recommended during therapy. If essential, monitor infant for sedation, poor feeding, and weight loss.
Amitriptyline and its metabolite nortriptyline are excreted in breast milk with an M/P ratio of approximately 1.0 for amitriptyline. Infant daily dose is about 1-2% of maternal weight-adjusted dose. No adverse effects reported in most infants; however, monitor for drowsiness, poor feeding. American Academy of Pediatrics considers amitriptyline compatible with breastfeeding.
No specific dose adjustments are established. Due to increased plasma volume and hepatic metabolism in pregnancy, therapeutic drug monitoring is recommended to ensure efficacy and avoid toxicity. Initiate at low doses and titrate based on clinical response and serum concentrations if available.
Pregnancy increases clearance of amitriptyline by 30-50% due to expanded plasma volume and enhanced hepatic metabolism. Serum levels may decrease, potentially requiring dose increase of 30-50% to maintain efficacy. Consider therapeutic drug monitoring (target trough 100-250 ng/m L) for dose titration. Postpartum dosing should be reduced to prepregnancy levels.
Asendin (amoxapine) is a dibenzoxazepine antidepressant with a 7-hydroxy metabolite that confers dopamine blockade, giving it a unique antipsychotic profile. Monitor for extrapyramidal symptoms and tardive dyskinesia, especially in elderly patients. Due to significant anticholinergic effects, use cautiously in patients with benign prostatic hyperplasia, narrow-angle glaucoma, or cognitive impairment. Avoid coadministration with MAOIs; allow at least 14 days between therapies. May cause a false-positive urine amphetamine screen due to structural similarity.
Do not discontinue abruptly; taper over 2-4 weeks to prevent withdrawal symptoms. Use with caution in patients with cardiac conduction defects (prolongs QTc interval). Serum levels >500 ng/m L are associated with toxicity. Start at 10-25 mg at bedtime for neuropathic pain. May precipitate mania in bipolar disorder.
Take exactly as prescribed; do not stop abruptly or adjust dose without consulting your doctor.,Avoid alcohol and other CNS depressants as they can increase drowsiness and dizziness.,May cause dry mouth; use sugar-free gum or candy to alleviate.,Report any unusual movements, especially of the face or tongue, or severe muscle stiffness.,May increase sensitivity to sunlight; use sunscreen and protective clothing.,Inform all healthcare providers you are taking this medication.
Take at bedtime to minimize daytime sedation.,Avoid alcohol and other CNS depressants.,Report symptoms of urinary retention, vision changes, or rapid heartbeat.,May cause dry mouth; use sugar-free gum or candy.,Avoid abrupt discontinuation; follow your doctor's tapering plan.,Notify your doctor if you experience suicidal thoughts or worsening depression.
No interactions on record
"Amitriptyline, a tricyclic antidepressant, may inhibit the metabolism of captopril, an ACE inhibitor, leading to increased serum concentrations of captopril. This elevation can potentiate captopril's antihypertensive effects and increase the risk of adverse effects such as hypotension, renal impairment, and hyperkalemia. Patients should be monitored closely for signs of exaggerated hypotensive response and electrolyte disturbances."
"Rifapentine, a potent inducer of cytochrome P450 (CYP) enzymes, specifically CYP3A4 and CYP2C19, significantly increases the hepatic metabolism of amitriptyline, a tricyclic antidepressant primarily metabolized by CYP2C19 and CYP3A4. This induction leads to markedly reduced plasma concentrations of amitriptyline and its active metabolite nortriptyline, potentially resulting in loss of antidepressant efficacy or relapse of depressive symptoms. Additionally, abrupt withdrawal of rifapentine without dose adjustment of amitriptyline may cause increased tricyclic levels and toxicity."
"Dapiprazole, an alpha-1 adrenergic receptor antagonist, and amitriptyline, a tricyclic antidepressant with significant anticholinergic properties, can have additive anticholinergic and sympatholytic effects when coadministered. This may lead to enhanced central nervous system depression, hypotension, urinary retention, and constipation. Patients should be monitored for excessive sedation, orthostatic hypotension, and anticholinergic toxicity."
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about ASENDIN vs AMITRIPTYLINE HYDROCHLORIDE, answered by our medical review team.
ASENDIN is a Tricyclic Antidepressant that works by Amoxapine, a dibenzoxazepine tricyclic antidepressant, primarily inhibits the reuptake of norepinephrine and serotonin. Its metabolite, 7-hydroxyamoxapine, exhibits dopamine D2 receptor antagonism, contributing to its antipsychotic effects.. AMITRIPTYLINE HYDROCHLORIDE is a Tricyclic Antidepressant that works by Inhibits reuptake of serotonin and norepinephrine, leading to increased concentrations at synaptic cleft; also blocks histamine H1, alpha-1 adrenergic, and muscarinic cholinergic receptors.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between ASENDIN and AMITRIPTYLINE HYDROCHLORIDE depend on the specific clinical indication. These are both Tricyclic Antidepressant agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of ASENDIN is: 50 mg orally three times daily, increased gradually to 100-200 mg/day in divided doses. Max 300 mg/day.. The standard adult dose of AMITRIPTYLINE HYDROCHLORIDE is: Oral: 25-150 mg daily in divided doses or as a single bedtime dose; maximum 300 mg/day.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between ASENDIN and AMITRIPTYLINE HYDROCHLORIDE in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. ASENDIN is classified as Category C. ASENDIN (amoxapine) is classified as FDA Pregnancy Category C. First trimester: Limited human data; animal studies show fetal toxicity at high doses. Risk of congenital malformatio. AMITRIPTYLINE HYDROCHLORIDE is classified as Category C. First trimester: Limited data suggest a small increased risk of congenital malformations, particularly cardiovascular defects. Second trimester: No specific malformation risk, but . Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.