Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
AMITID vs ANEXSIA 7.5/325
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Amitriptyline inhibits the reuptake of serotonin and norepinephrine, increasing their levels in the synaptic cleft. It also blocks histamine H1, alpha-adrenergic, and muscarinic receptors.
Hydrocodone is a mu-opioid receptor agonist, producing analgesia and euphoria. Acetaminophen inhibits cyclooxygenase (COX) enzymes, reducing prostaglandin synthesis and providing analgesic and antipyretic effects.
Major depressive disorder,Neuropathic pain,Fibromyalgia,Migraine prophylaxis,Chronic tension-type headache,Irritable bowel syndrome,Enuresis
Management of moderate to moderately severe pain where treatment with an opioid is appropriate and for which alternative treatments are inadequate
75–150 mg orally once daily at bedtime; maximum 200 mg daily. For depression, initial dose 25–75 mg/day, titrate up to 150 mg/day. For neuropathic pain, start 10–25 mg at bedtime, increase to 25–100 mg/day.
1 tablet (hydrocodone 7.5 mg / acetaminophen 325 mg) orally every 4 to 6 hours as needed for pain; maximum 6 tablets per day (hydrocodone 45 mg / acetaminophen 1950 mg).
Terminal elimination half-life is 7-10 hours; clinically, steady-state is reached within 2-3 days.
Hydrocodone: 3.8-4.5 hours (immediate-release). Acetaminophen: 2-3 hours. Clinical note: Half-life prolonged in hepatic impairment; requires dose adjustment.
Hepatic via CYP2D6, CYP2C19, CYP3A4; active metabolite nortriptyline.
Hydrocodone: CYP3A4 and CYP2D6; Acetaminophen: primarily via glucuronidation (UGT1A1, UGT1A6, UGT1A9) and sulfation, with minor oxidation by CYP2E1.
Renal: 60-80% as metabolites, <5% unchanged; Biliary/Fecal: 20-30% as metabolites.
Renal: ~90-100% as hydrocodone metabolites (conjugated) and unchanged hydrocodone; ~60% as acetaminophen metabolites (glucuronide, sulfate, cysteine); <5% unchanged acetaminophen. Biliary/fecal: <5%.
90-95% bound primarily to albumin and α1-acid glycoprotein.
Hydrocodone: ~20-30% (albumin). Acetaminophen: ~10-25% (albumin).
3-5 L/kg; indicates extensive tissue distribution.
Hydrocodone: 3-4 L/kg (extensive tissue distribution). Acetaminophen: ~1 L/kg (uniformly distributed).
Oral: 60-70%; Intravenous: 100%.
Oral: Hydrocodone ~70% (high first-pass metabolism); Acetaminophen ~85-90% (minimal first-pass).
GFR ≥30 m L/min: no adjustment. GFR 15–29 m L/min: reduce dose by 50%. GFR <15 m L/min: contraindicated or use with extreme caution, maximum 25 mg/day.
For GFR 30-59 m L/min: administer every 6 hours; maximum 4 tablets per day. For GFR 15-29 m L/min: administer every 8 hours; maximum 3 tablets per day. For GFR <15 m L/min: not recommended due to accumulation of metabolites.
Child-Pugh A: no adjustment. Child-Pugh B: reduce dose by 50%. Child-Pugh C: avoid use.
Child-Pugh Class A: no adjustment necessary. Child-Pugh Class B: reduce dose by 25-50% and extend dosing interval to every 6-8 hours; maximum 4 tablets per day. Child-Pugh Class C: contraindicated due to risk of hepatotoxicity.
Not FDA-approved for use in children <12 years. For adolescent depression (off-label): start 25 mg/day, titrate up to 50–100 mg/day. Weight-based: 1–3 mg/kg/day, not to exceed 150 mg/day.
Not recommended for pediatric patients; safety and efficacy not established for children under 18 years. For adolescents ≥18 years: adult dosing.
Start at 10–25 mg orally at bedtime; increase by 10–25 mg every 3–7 days to effective dose, typically 50–75 mg/day. Maximum 100 mg/day due to increased risk of anticholinergic effects, sedation, and orthostatic hypotension.
Initiate at 1 tablet (hydrocodone 5 mg / acetaminophen 325 mg) every 6 hours as needed; titrate cautiously due to increased sensitivity, decreased renal function, and risk of respiratory depression. Maximum 4 tablets per day.
Antidepressants increase the risk of suicidal thinking and behavior in children, adolescents, and young adults with major depressive disorder and other psychiatric disorders.
Addiction, abuse, and misuse; life-threatening respiratory depression; accidental ingestion; neonatal opioid withdrawal syndrome; risks from concomitant use with benzodiazepines or other CNS depressants; hepatotoxicity due to acetaminophen.
Clinical worsening and suicide risk,Serotonin syndrome,Cardiovascular effects (QT prolongation, arrhythmia),Anticholinergic effects,Seizures,Angle-closure glaucoma,Urinary retention,Hepatic impairment,Hyponatremia
Risk of opioid addiction, abuse, and misuse; life-threatening respiratory depression; accidental ingestion; neonatal opioid withdrawal syndrome; risks from concomitant use of alcohol, benzodiazepines, or other CNS depressants; hepatotoxicity; severe hypotension; adrenal insufficiency; seizures; GI obstruction; impaired mental/physical abilities; use in elderly, cachectic, or debilitated patients; renal impairment; hepatic impairment; pregnancy; labor and delivery; nursing mothers; pediatric use; driving and operating machinery.
Hypersensitivity to amitriptyline,Concomitant use with MAOIs (within 14 days),Acute recovery phase after myocardial infarction,Concurrent use of cisapride or other QT-prolonging drugs
Significant respiratory depression; acute or severe bronchial asthma; known or suspected GI obstruction; hypersensitivity to hydrocodone or acetaminophen; concomitant use of MAOIs or within 14 days of such therapy.
Avoid grapefruit and grapefruit juice as they may increase drug levels. Tyramine-rich foods (aged cheese, cured meats, fermented products) should be limited due to risk of hypertensive crisis. Maintain adequate fluid intake to prevent constipation.
Avoid alcohol consumption due to increased risk of acetaminophen hepatotoxicity and CNS depression. No specific food restrictions, but grapefruit juice may theoretically affect hydrocodone metabolism via CYP3A4 inhibition; however, clinical significance is uncertain.
First trimester: Amitriptyline (likely the active ingredient in AMITID) is associated with a small increased risk of congenital malformations, particularly cardiovascular defects, based on observational studies. Absolute risk is low. Second and third trimesters: Chronic use may lead to neonatal adaptation syndrome (irritability, respiratory distress) and anticholinergic effects (e.g., constipation, urinary retention). Late third trimester exposure may increase risk of persistent pulmonary hypertension of the newborn (PPHN).
FDA Category C (hydrocodone) and Category D (acetaminophen) in third trimester. First trimester: Acetaminophen associated with rare gastroschisis; hydrocodone risk of neural tube defects. Second trimester: No major malformations except with prolonged opioid use. Third trimester: Acetaminophen safe; hydrocodone risk of neonatal opioid withdrawal syndrome (NOWS). Avoid near term.
Amitriptyline and its active metabolite nortriptyline are excreted into breast milk with a milk-to-plasma (M/P) ratio of approximately 0.5–1.5. Relative infant dose is low (estimated <2% of weight-adjusted maternal dose). No adverse effects reported in infants followed prospectively. The American Academy of Pediatrics considers amitriptyline compatible with breastfeeding. However, monitor infant for sedation, poor feeding, and growth.
Hydrocodone/acetaminophen excreted in breast milk. M/P ratio unknown. Hydrocodone relative infant dose <3% of weight-adjusted maternal dose. Acetaminophen relative infant dose <2%. Use with caution; monitor infant for sedation, apnea, poor feeding. Highest risk in CYP2D6 ultrarapid metabolizers.
Pharmacokinetic changes in pregnancy (increased volume of distribution, hepatic metabolism, renal clearance) may reduce serum drug concentrations. Therapeutic drug monitoring (if available) can guide dose adjustments; clinical response may require dose increases by 30–50% in the second and third trimesters. Avoid abrupt withdrawal; taper if discontinuing.
Increased clearance of hydrocodone in pregnancy may require dose adjustment; monitor for inadequate analgesia. Acetaminophen pharmacokinetics unchanged. Avoid high doses (hepatotoxicity risk). Consider baseline hepatic function. No specific dose adjustment recommended; titrate to effect.
Amitriptyline is a tricyclic antidepressant with strong anticholinergic effects; monitor for QT prolongation, especially in elderly or those with cardiac disease. Start low (10-25 mg at bedtime) and titrate slowly. Avoid in recent MI, narrow-angle glaucoma, and urinary retention. Use with caution in seizure disorders.
ANEXSIA 7.5/325 (hydrocodone/acetaminophen) carries a boxed warning for acetaminophen hepatotoxicity; maximum acetaminophen dose from all sources should not exceed 4 g/day. Hydrocodone is metabolized by CYP2D6 to hydromorphone; ultrarapid metabolizers may experience toxicity. Avoid concurrent use with other CNS depressants including alcohol. Prescribe with caution in patients with renal impairment (hydrocodone accumulation) or hepatic impairment (acetaminophen toxicity). Monitor for signs of respiratory depression, especially at therapy initiation and dose titration. Use the lowest effective dose for the shortest duration.
Take this medication at bedtime as it may cause drowsiness.,Avoid alcohol and other CNS depressants.,Do not stop abruptly; taper under medical supervision to avoid withdrawal symptoms.,May cause dry mouth, constipation, blurred vision; report severe side effects like fainting or irregular heartbeat.,Full therapeutic effect may take 2-4 weeks.
Do not exceed 6 tablets per day due to acetaminophen content.,Avoid alcohol while taking this medication.,Do not drive or operate heavy machinery until you know how this medication affects you.,Take exactly as prescribed; do not share with others.,Seek emergency help if you experience difficulty breathing, severe drowsiness, or signs of allergic reaction.,Store securely out of reach of children and dispose of unused medication properly.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about AMITID vs ANEXSIA 7.5/325, answered by our medical review team.
AMITID is a Tricyclic Antidepressant that works by Amitriptyline inhibits the reuptake of serotonin and norepinephrine, increasing their levels in the synaptic cleft. It also blocks histamine H1, alpha-adrenergic, and muscarinic receptors.. ANEXSIA 7.5/325 is a Opioid Analgesic Combination that works by Hydrocodone is a mu-opioid receptor agonist, producing analgesia and euphoria. Acetaminophen inhibits cyclooxygenase (COX) enzymes, reducing prostaglandin synthesis and providing analgesic and antipyretic effects.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between AMITID and ANEXSIA 7.5/325 depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of AMITID is: 75–150 mg orally once daily at bedtime; maximum 200 mg daily. For depression, initial dose 25–75 mg/day, titrate up to 150 mg/day. For neuropathic pain, start 10–25 mg at bedtime, increase to 25–100 mg/day.. The standard adult dose of ANEXSIA 7.5/325 is: 1 tablet (hydrocodone 7.5 mg / acetaminophen 325 mg) orally every 4 to 6 hours as needed for pain; maximum 6 tablets per day (hydrocodone 45 mg / acetaminophen 1950 mg).. 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 AMITID and ANEXSIA 7.5/325 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. AMITID is classified as Category C. First trimester: Amitriptyline (likely the active ingredient in AMITID) is associated with a small increased risk of congenital malformations, particularly cardiovascular defects, . ANEXSIA 7.5/325 is classified as Category C. FDA Category C (hydrocodone) and Category D (acetaminophen) in third trimester. First trimester: Acetaminophen associated with rare gastroschisis; hydrocodone risk of neural tube d. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.