Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
AMITRIPTYLINE HYDROCHLORIDE vs ANEXSIA 7.5/650
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Inhibits reuptake of serotonin and norepinephrine, leading to increased concentrations at synaptic cleft; also blocks histamine H1, alpha-1 adrenergic, and muscarinic cholinergic receptors.
Hydrocodone is a mu-opioid receptor agonist that inhibits ascending pain pathways and alters pain perception; acetaminophen inhibits cyclooxygenase (COX) enzymes, primarily in the CNS, reducing prostaglandin synthesis and fever.
Major depressive disorder,Neuropathic pain,Fibromyalgia,Migraine prophylaxis,Chronic tension-type headache,Insomnia (off-label),Irritable bowel syndrome (off-label)
Management of acute pain severe enough to require an opioid analgesic and for which alternative treatments are inadequate
Oral: 25-150 mg daily in divided doses or as a single bedtime dose; maximum 300 mg/day.
1 tablet orally every 4 to 6 hours as needed; maximum 6 tablets per day.
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.
Hydrocodone: Terminal half-life 3.8-7.2 hours (mean 5.6 h). Acetaminophen: 1.5-2.5 hours (therapeutic) but prolonged to >4 hours in overdose with hepatotoxicity risk.
Primarily hepatic via CYP2D6, CYP3A4, CYP1A2, and CYP2C19; active metabolite nortriptyline; undergoes demethylation, hydroxylation, and conjugation.
Hydrocodone: CYP3A4 and CYP2D6; acetaminophen: primarily liver glucuronidation (UGT1A1, UGT1A6, UGT1A9) and sulfation (SULT1A1, SULT1A3), with minor CYP2E1 oxidation.
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.
Hydrocodone: Renal elimination of metabolites (hydromorphone, norhydrocodone) and unchanged drug accounts for ~60-90% of clearance. Acetaminophen: ~85% of dose is excreted in urine as glucuronide and sulfate conjugates; 5-10% unchanged; 2-5% as mercapturate.
Approximately 94-96%; primarily bound to alpha-1-acid glycoprotein (AAG), with minor binding to albumin and lipoproteins.
Hydrocodone: ~36% bound to serum proteins. Acetaminophen: 10-25% bound (minimal binding).
10-20 L/kg (large Vd due to extensive tissue binding); clinical meaning: high tissue penetration, especially CNS, and slow redistribution from tissues.
Hydrocodone: Vd ~3-5 L/kg (wide distribution). Acetaminophen: Vd ~0.9-1.0 L/kg (primarily body water).
Oral: 30-60% due to extensive first-pass metabolism (CYP2C19, CYP3A4, CYP2D6); significant interindividual variability.
Oral: Hydrocodone ~70-80% (variable first-pass). Acetaminophen ~63-89% (mean 75-80%).
GFR 10-50 m L/min: use 50% of normal dose; GFR <10 m L/min: use 25% of normal dose.
Cr Cl <30 m L/min: contraindicated; Cr Cl 30-60 m L/min: maximum 3 tablets per day; given the hydrocodone component, avoid in severe renal impairment.
Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: avoid use.
Child-Pugh Class A: no adjustment; Child-Pugh Class B: reduce dose by 50% and monitor; Child-Pugh Class C: contraindicated due to hydrocodone.
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.
Not recommended in pediatric patients due to risk of respiratory depression; for ages <18, contraindicated.
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.
Initiate with lowest effective dose, monitor for respiratory depression and constipation; maximum 4 tablets per day in patients >65 years.
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.
Risk of addiction, abuse, and misuse; life-threatening respiratory depression; accidental ingestion (especially in children) can be fatal; neonatal opioid withdrawal syndrome; cytochrome P450 3A4 interaction (concomitant use with CYP3A4 inhibitors may increase hydrocodone levels); risk of medication errors (confusion between different strengths).
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.
Addiction, abuse, and misuse; respiratory depression; neonatal opioid withdrawal syndrome; interactions with CNS depressants; risk of serotonin syndrome with serotonergic drugs; adrenal insufficiency; hypotension; seizures; gastrointestinal obstruction; severe cutaneous reactions (acetaminophen); hepatotoxicity (acetaminophen overdose); acute abdominal conditions; impaired mental/physical abilities; elderly/debilitated patients; renal/hepatic impairment.
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.
Significant respiratory depression; acute or severe bronchial asthma (without monitoring or resuscitative equipment); known or suspected gastrointestinal obstruction (including paralytic ileus); hypersensitivity to hydrocodone or acetaminophen; use with MAOIs or within 14 days of such therapy.
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.
Avoid alcohol due to increased risk of acetaminophen hepatotoxicity and additive CNS depression. Grapefruit juice may increase hydrocodone absorption; consider avoiding. No other significant food interactions.
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.
FDA Category C. First trimester: Possible increased risk of cardiac defects with oxycodone. Second/third trimester: Chronic use may lead to neonatal opioid withdrawal syndrome; no clear teratogenicity. Acetaminophen is generally safe, but high doses may be hepatotoxic.
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.
Oxycodone: M/P ratio ~0.8-3; present in milk; risk of neonatal sedation. Acetaminophen: M/P ~0.8-1, low risk. Avoid due to oxycodone; consider alternative analgesic.
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.
Increased clearance of oxycodone in pregnancy may require increased dose; acetaminophen pharmacokinetics unchanged. Adjust based on pain control and withdrawal risk.
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.
Fixed-dose combination of hydrocodone bitartrate (7.5 mg) and acetaminophen (650 mg). Hydrocodone is a schedule II controlled substance with high abuse potential. Acetaminophen hepatotoxicity risk increases above 3 g/day; prescribe no more than 4 doses per day. Monitor for respiratory depression, especially in opioid-naïve patients. Avoid in severe hepatic impairment. Use with caution in patients with COPD, sleep apnea, or concurrent CNS depressants. Consider naloxone co-prescription if high opioid dose or concurrent benzodiazepine use.
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.
Take exactly as prescribed; do not increase dose or frequency.,Do not take with alcohol or other medications containing acetaminophen.,May cause drowsiness or dizziness; avoid driving or operating machinery until effects are known.,Store securely out of reach of children and others; dispose of unused tablets properly.,Seek emergency care for difficulty breathing, severe sedation, or signs of allergic reaction.,Do not abruptly stop after prolonged use; withdrawal symptoms may occur.
"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."
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about AMITRIPTYLINE HYDROCHLORIDE vs ANEXSIA 7.5/650, answered by our medical review team.
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.. ANEXSIA 7.5/650 is a Opioid Analgesic Combination that works by Hydrocodone is a mu-opioid receptor agonist that inhibits ascending pain pathways and alters pain perception; acetaminophen inhibits cyclooxygenase (COX) enzymes, primarily in the CNS, reducing prostaglandin synthesis and fever.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between AMITRIPTYLINE HYDROCHLORIDE and ANEXSIA 7.5/650 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 AMITRIPTYLINE HYDROCHLORIDE is: Oral: 25-150 mg daily in divided doses or as a single bedtime dose; maximum 300 mg/day.. The standard adult dose of ANEXSIA 7.5/650 is: 1 tablet orally every 4 to 6 hours as needed; maximum 6 tablets per 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 AMITRIPTYLINE HYDROCHLORIDE and ANEXSIA 7.5/650 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. 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 . ANEXSIA 7.5/650 is classified as Category C. FDA Category C. First trimester: Possible increased risk of cardiac defects with oxycodone. Second/third trimester: Chronic use may lead to neonatal opioid withdrawal syndrome; no . Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.