Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
LEVORPHANOL TARTRATE vs ANEXSIA
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Levorphanol is a potent opioid analgesic that acts as a mu-opioid receptor agonist. It also has NMDA receptor antagonist activity, inhibits norepinephrine and serotonin reuptake, and acts as a sigma receptor agonist, contributing to its analgesic effects and reduced tolerance development.
ANEXSIA is a combination of hydrocodone and acetaminophen. Hydrocodone is an opioid agonist that binds to mu-opioid receptors in the central nervous system, altering pain perception and emotional response to pain. Acetaminophen's analgesic mechanism is not fully understood but involves inhibition of COX enzymes in the CNS and modulation of descending serotonergic pathways.
Management of moderate to severe pain where opioid treatment is appropriate,Off-label: treatment-refractory neuropathic pain, chronic pain syndromes
Relief of moderate to moderately severe pain
2 mg orally every 6-8 hours as needed for pain; for opioid-tolerant patients, doses up to 4 mg orally every 6-8 hours may be used. Parenterally: 1-2 mg subcutaneously or intramuscularly every 6-8 hours; may be given intravenously at 0.5-1 mg every 6-8 hours.
50-100 mg orally every 4-6 hours as needed; maximum 400 mg/day.
11-16 hours; extended in hepatic impairment (up to 30 hours).
Terminal elimination half-life is 4-6 hours in adults with normal renal function; prolonged to 12-24 hours in severe renal impairment (Cr Cl <30 m L/min).
Primarily hepatic via glucuronidation and N-demethylation; CYP450 involvement not fully characterized.
Hydrocodone is metabolized via CYP2D6 and CYP3A4 to hydromorphone and norhydrocodone. Acetaminophen is primarily metabolized via hepatic glucuronidation and sulfation; a minor pathway via CYP2E1 produces NAPQI, which is detoxified by glutathione.
Renal: approximately 30% as unchanged drug and 50% as glucuronide conjugates; fecal: 20% via biliary excretion.
Approximately 70% renal (unchanged drug and metabolites), 20% biliary/fecal, 10% other.
Approximately 50% bound to albumin.
Approximately 95% bound to plasma albumin and alpha-1-acid glycoprotein.
10-15 L/kg; extensive tissue distribution.
0.2-0.4 L/kg, indicating limited extravascular distribution primarily confined to plasma and interstitial fluid.
Oral: 50-70% (first-pass effect); intravenous: 100%.
Oral: 80-90%; Intramuscular: 90-100%; Rectal: 70-80%.
Cr Cl 10-50 m L/min: Administer 75% of usual dose at extended intervals (e.g., every 12 hours). Cr Cl <10 m L/min: Administer 50% of usual dose at extended intervals (e.g., every 12-24 hours). For patients on dialysis, use with caution and reduce dose; not well-studied.
GFR 30-89 m L/min: no adjustment; GFR 15-29 m L/min: 50% dose reduction; GFR <15 m L/min: avoid use.
Child-Pugh Class A: No adjustment needed. Child-Pugh Class B: Reduce dose by 50% and administer at extended intervals (e.g., every 12 hours). Child-Pugh Class C: Avoid use; if necessary, reduce dose by 75% and monitor closely.
Child-Pugh A: no adjustment; Child-Pugh B: 50% dose reduction; Child-Pugh C: avoid use.
Not recommended for use in pediatric patients due to lack of safety and efficacy data; use in children under 18 years is generally avoided. For palliative care in older children, consult specialist.
1-2 mg/kg/dose orally every 6 hours; maximum 6 mg/kg/day.
Start at 50% of the usual adult dose (e.g., 1 mg orally every 6-8 hours) due to increased sensitivity and reduced clearance; titrate carefully with close monitoring for respiratory depression and constipation.
Initiate at 25 mg every 6 hours; increase cautiously; monitor renal function.
Risk of addiction, abuse, and misuse; life-threatening respiratory depression; accidental ingestion; neonatal opioid withdrawal syndrome; risks from concomitant use with benzodiazepines or other CNS depressants.
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 from acetaminophen.
Respiratory depression: potentially fatal, especially at initiation and dose escalation,Adrenal insufficiency,Severe hypotension,Seizures,Serotonin syndrome,Risks from concomitant CNS depressants,Impaired mental or physical abilities
Risk of respiratory depression, especially in elderly or debilitated patients; adrenal insufficiency; severe hypotension; seizures; opioid-induced hyperalgesia; acetaminophen hepatotoxicity (avoid exceeding 4 g/day); serotonin syndrome if used with serotonergic agents.
Significant respiratory depression,Acute or severe bronchial asthma,Known or suspected gastrointestinal obstruction,Concurrent use of MAOIs or within 14 days,Hypersensitivity to levorphanol
Hypersensitivity to hydrocodone or acetaminophen; significant respiratory depression; acute or severe bronchial asthma in an unmonitored setting; known or suspected GI obstruction; severe hepatic impairment; concomitant use of MAOIs or within 14 days.
Avoid grapefruit juice as it may increase levorphenol levels via CYP3A4 inhibition. High-fat meals may delay absorption but not overall extent. Alcohol must be avoided due to additive CNS depression.
Avoid alcohol; may increase risk of hepatotoxicity and GI bleeding. Limit caffeine intake from coffee, tea, cola, or energy drinks due to added caffeine content. High-fat meals may delay absorption; take on empty stomach for faster onset if tolerated.
Levorphanol is an opioid agonist; limited data in pregnancy. First trimester: potential for neural tube defects based on animal studies; human risk unclear. Second/third trimesters: risk of fetal opioid dependence, preterm labor, and intrauterine growth restriction. Use only if benefit outweighs risk.
First trimester: Data are limited; no increased risk of major malformations reported in small studies. Second and third trimesters: Associated with premature closure of the ductus arteriosus and oligohydramnios due to fetal renal effects; avoid use after 30 weeks gestation.
Unknown if levorphanol is excreted in human milk; other opioids are present in breast milk. Consider benefits of breastfeeding vs. risk of infant opioid exposure (respiratory depression, withdrawal). M/P ratio not established.
Excreted into breast milk in low concentrations (M/P ratio not established). Not recommended during breastfeeding due to potential for adverse effects in the infant, including renal impairment and gastrointestinal bleeding.
Pregnancy may alter opioid pharmacokinetics (increased clearance, volume of distribution). Dose adjustments may be needed to maintain analgesic efficacy; consider lower starting doses and titrate to effect. Avoid use during first and third trimesters; taper to avoid withdrawal if discontinuing. No specific dose adjustment guidelines are established; individualize based on response and risk.
Dose adjustment not generally required; however, due to increased renal clearance in pregnancy, shortened dosing intervals may be necessary for sustained efficacy. Use lowest effective dose for shortest duration.
Levorphanol is a potent mu-opioid agonist with a long half-life (12-16 hours) and active metabolites; avoid use in opioid-naive patients due to risk of respiratory depression. It has NMDA antagonist activity, which may provide benefit in neuropathic pain but also contributes to psychotomimetic effects. Equianalgesic dose: 2 mg oral levorphenol ≈ 10 mg morphine. Accumulation occurs with repeated dosing; monitor for sedation and respiratory depression.
ANEXSIA is a combination analgesic containing paracetamol, ibuprofen, and caffeine. It is contraindicated in patients with active peptic ulcer disease, severe hepatic impairment, or hypersensitivity to NSAIDs. Avoid concurrent use with other NSAIDs or paracetamol-containing products. Monitor renal function in elderly or dehydrated patients. Caffeine may exacerbate anxiety or insomnia.
Take exactly as prescribed; do not increase dose or frequency without consulting your doctor.,Avoid alcohol and other CNS depressants (e.g., benzodiazepines, sedatives) as they increase risk of severe drowsiness and breathing problems.,Do not drive or operate heavy machinery until you know how levorphenol affects you.,Do not stop abruptly; withdrawal symptoms may occur. Taper under medical supervision.,Constipation is common; increase fluid and fiber intake, and consider stool softeners.,Store securely out of reach of others, as misuse can cause overdose and death.,Report any difficulty breathing, severe drowsiness, or confusion immediately.
Do not exceed recommended dose; overdosage of paracetamol can cause liver damage.,Take with food or milk to reduce gastrointestinal upset.,Avoid alcohol while taking this medication to reduce risk of liver toxicity and GI bleeding.,Discontinue use and consult if signs of allergic reaction, GI bleeding, or liver problems occur.,Caffeine may cause nervousness, insomnia, or increased heart rate; limit caffeine-containing foods and beverages.
"The combination of Biperiden, an anticholinergic agent used for Parkinsonism, and Levorphanol, a potent opioid analgesic, can lead to additive central nervous system depression and increased anticholinergic side effects. Specifically, both drugs can cause sedation, confusion, and respiratory depression, particularly in elderly patients or those with compromised central nervous system function. Additionally, the anticholinergic effects of Biperiden (e.g., dry mouth, urinary retention, constipation) may be exacerbated by Levorphanol, which also has mild anticholinergic properties, leading to enhanced adverse effects."
"The combination of meprobamate, a carbamate anxiolytic with central nervous system (CNS) depressant properties, and levorphanol, a potent opioid analgesic, results in additive or synergistic CNS depression. This leads to increased risks of profound sedation, respiratory depression, coma, and death. Patients experience compounded impairment of cognitive and motor functions, necessitating cautious use or avoidance."
"Levorphanol, a potent mu-opioid receptor agonist, and Bromazepam, a benzodiazepine acting as a positive allosteric modulator of GABA-A receptors, synergistically depress the central nervous system (CNS), particularly affecting respiratory centers in the brainstem. This combination significantly increases the risk of severe respiratory depression, hypotension, profound sedation, coma, and death. Additive CNS depression can also impair cognitive and motor function, increasing fall risk and accidental injury."
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about LEVORPHANOL TARTRATE vs ANEXSIA, answered by our medical review team.
LEVORPHANOL TARTRATE is a Opioid Analgesic that works by Levorphanol is a potent opioid analgesic that acts as a mu-opioid receptor agonist. It also has NMDA receptor antagonist activity, inhibits norepinephrine and serotonin reuptake, and acts as a sigma receptor agonist, contributing to its analgesic effects and reduced tolerance development.. ANEXSIA is a Opioid Analgesic Combination that works by ANEXSIA is a combination of hydrocodone and acetaminophen. Hydrocodone is an opioid agonist that binds to mu-opioid receptors in the central nervous system, altering pain perception and emotional response to pain. Acetaminophen's analgesic mechanism is not fully understood but involves inhibition of COX enzymes in the CNS and modulation of descending serotonergic pathways.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between LEVORPHANOL TARTRATE and ANEXSIA 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 LEVORPHANOL TARTRATE is: 2 mg orally every 6-8 hours as needed for pain; for opioid-tolerant patients, doses up to 4 mg orally every 6-8 hours may be used. Parenterally: 1-2 mg subcutaneously or intramuscularly every 6-8 hours; may be given intravenously at 0.5-1 mg every 6-8 hours.. The standard adult dose of ANEXSIA is: 50-100 mg orally every 4-6 hours as needed; maximum 400 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 LEVORPHANOL TARTRATE and ANEXSIA 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. LEVORPHANOL TARTRATE is classified as Category C. Levorphanol is an opioid agonist; limited data in pregnancy. First trimester: potential for neural tube defects based on animal studies; human risk unclear. Second/third trimesters. ANEXSIA is classified as Category C. First trimester: Data are limited; no increased risk of major malformations reported in small studies. Second and third trimesters: Associated with premature closure of the ductus . Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.