Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ROXICET 5/500 vs ANEXSIA
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Oxycodone is a full opioid agonist that binds to mu-opioid receptors in the CNS, inhibiting ascending pain pathways and altering pain perception. Acetaminophen inhibits cyclooxygenase (COX) enzymes, primarily in the CNS, reducing prostaglandin synthesis and producing analgesic and antipyretic effects.
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 moderately severe pain where treatment with an opioid is appropriate and for which alternative treatments are inadequate
Relief of moderate to moderately severe pain
1-2 tablets (5-10 mg oxycodone / 325-650 mg acetaminophen) orally every 4-6 hours as needed for pain; maximum 12 tablets per day (60 mg oxycodone / 6000 mg acetaminophen) in 24 hours.
50-100 mg orally every 4-6 hours as needed; maximum 400 mg/day.
Oxycodone: 3-5 hours (immediate-release); Acetaminophen: 2-3 hours. In hepatic impairment, oxycodone half-life prolonged (up to 12-15 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).
Oxycodone is metabolized primarily via CYP3A4 and CYP2D6 to noroxycodone and oxymorphone. Acetaminophen is metabolized mainly via glucuronidation (UGT1A1, UGT1A6, UGT1A9) and sulfation, with minor oxidation by CYP2E1 and CYP1A2 producing N-acetyl-p-benzoquinone imine (NAPQI).
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.
Oxycodone: primarily hepatic metabolism to noroxycodone, oxymorphone, and conjugates; renal elimination of metabolites (about 60-87% as unchanged and metabolites), fecal < 10%. Acetaminophen: renal elimination of conjugates (90-100%), <5% unchanged.
Approximately 70% renal (unchanged drug and metabolites), 20% biliary/fecal, 10% other.
Oxycodone: ~45% bound to albumin; Acetaminophen: 10-25% bound to albumin.
Approximately 95% bound to plasma albumin and alpha-1-acid glycoprotein.
Oxycodone: 2-3 L/kg (extensive tissue distribution); Acetaminophen: 0.8-1.0 L/kg (distribution throughout body water).
0.2-0.4 L/kg, indicating limited extravascular distribution primarily confined to plasma and interstitial fluid.
Oxycodone oral: 60-87% (high first-pass metabolism varies); Acetaminophen oral: 80-90%.
Oral: 80-90%; Intramuscular: 90-100%; Rectal: 70-80%.
Cr Cl 30-50 m L/min: administer every 6 hours. Cr Cl 10-29 m L/min: administer every 8 hours. Cr Cl <10 m L/min: use not recommended due to oxycodone accumulation; consider alternative.
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. Child-Pugh Class B: reduce dose by 50% and extend dosing interval to every 8 hours. Child-Pugh Class C: contraindicated due to acetaminophen hepatotoxicity.
Child-Pugh A: no adjustment; Child-Pugh B: 50% dose reduction; Child-Pugh C: avoid use.
Not typically recommended; use weight-based dosing of oxycodone 0.1-0.2 mg/kg/dose (max 5 mg/dose) every 4-6 hours as needed, with acetaminophen component not to exceed 75 mg/kg/day. Not approved for children <12 years.
1-2 mg/kg/dose orally every 6 hours; maximum 6 mg/kg/day.
Initiate at lowest dose (one tablet every 6 hours) and titrate cautiously. Monitor for respiratory depression, sedation, and constipation. Avoid doses >4 tablets per day unless tolerated.
Initiate at 25 mg every 6 hours; increase cautiously; monitor renal function.
Addiction, abuse, and misuse; life-threatening respiratory depression; accidental ingestion of even one dose of oxycodone, especially by children, can cause fatal overdose; neonatal opioid withdrawal syndrome; cytochrome P450 3A4 interaction with concurrent use of benzodiazepines or other CNS depressants; hepatotoxicity due to acetaminophen (dose-related).
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.
Risk of opioid addiction, abuse, and misuse; life-threatening respiratory depression; risk of accidental ingestion; neonatal opioid withdrawal syndrome if used during pregnancy; risk of severe hypotension; risk of hepatotoxicity due to acetaminophen; risk of serotonin syndrome if co-administered with serotonergic drugs; adrenal insufficiency; risk of seizures; risk of increased intracranial pressure; severe renal or hepatic impairment; drug interactions with CNS depressants and CYP3A4 inhibitors/inducers.
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.
Hypersensitivity to oxycodone, acetaminophen, or any component of the formulation; significant respiratory depression; acute or severe bronchial asthma in an unmonitored setting or without resuscitative equipment; known or suspected gastrointestinal obstruction, including paralytic ileus; severe hepatic impairment (for acetaminophen component).
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 alcohol and grapefruit juice. High-fat meals may delay absorption of oxycodone, but does not affect total exposure.
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.
Pregnancy Category C (oxycodone) and D (acetaminophen at high doses). Oxycodone: Risk of neonatal opioid withdrawal syndrome (NOWS) with prolonged use in third trimester; risk of respiratory depression near term. Acetaminophen: Epidemiologic data not conclusively linked to major malformations at therapeutic doses, but high doses may be associated with fetal hepatotoxicity. FDA warns against chronic use during pregnancy due to NOWS.
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.
Oxycodone is excreted into breast milk with relative infant dose (RID) of 1.7-6.2% of maternal weight-adjusted dose; M/P ratio not well established (estimated ~1.3-3.7). Acetaminophen RID ~1-2%, M/P ratio ~0.91-1.0. Caution: Monitor infant for somnolence, respiratory depression, poor feeding. Avoid in breastfeeding women with CYP2D6 ultra-rapid metabolizer status due to increased morphine production.
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.
Oxycodone: Increased clearance and volume of distribution in pregnancy may require higher doses for adequate analgesia; dose should be titrated to effect. Acetaminophen: Pharmacokinetic changes minimal at therapeutic doses; no routine dose adjustment needed, but limit to <3000 mg/day to avoid maternal hepatotoxicity. Postpartum: Oxycodone doses may need reduction due to normalization of clearance.
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.
ROXICET 5/500 contains oxycodone (5 mg) and acetaminophen (500 mg). The acetaminophen component limits total daily use to avoid hepatotoxicity; maximum 4 g/day from all sources. Oxycodone is a Schedule II controlled substance with high abuse potential. Use with caution in patients with respiratory compromise, head injury, or hepatic impairment. Coadministration with alcohol or other CNS depressants increases sedation and respiratory depression risk. Consider naloxone co-prescription for high-risk patients.
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 only as prescribed; do not exceed 8 tablets in 24 hours due to acetaminophen.,Avoid alcohol and medications containing acetaminophen (e.g., Tylenol, cold remedies) to prevent liver damage.,Do not crush or chew tablets—swallow whole.,May cause drowsiness or dizziness; avoid driving or operating machinery until effects known.,Store securely out of reach of others; dispose of unused tablets via drug take-back program.,Do not share with others; misuse can cause addiction, overdose, or death.,Seek emergency help if signs of overdose: slow breathing, extreme drowsiness, confusion, or loss of consciousness.
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.
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 ROXICET 5/500 vs ANEXSIA, answered by our medical review team.
ROXICET 5/500 is a Opioid Analgesic Combination that works by Oxycodone is a full opioid agonist that binds to mu-opioid receptors in the CNS, inhibiting ascending pain pathways and altering pain perception. Acetaminophen inhibits cyclooxygenase (COX) enzymes, primarily in the CNS, reducing prostaglandin synthesis and producing analgesic and antipyretic effects.. 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 ROXICET 5/500 and ANEXSIA depend on the specific clinical indication. These are both Opioid Analgesic Combination agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of ROXICET 5/500 is: 1-2 tablets (5-10 mg oxycodone / 325-650 mg acetaminophen) orally every 4-6 hours as needed for pain; maximum 12 tablets per day (60 mg oxycodone / 6000 mg acetaminophen) in 24 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 ROXICET 5/500 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. ROXICET 5/500 is classified as Category C. Pregnancy Category C (oxycodone) and D (acetaminophen at high doses). Oxycodone: Risk of neonatal opioid withdrawal syndrome (NOWS) with prolonged use in third trimester; risk of r. 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.