Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ROXICET vs ANEXSIA
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Roxicet is a combination of oxycodone, a full mu-opioid receptor agonist, and acetaminophen, which inhibits cyclooxygenase (COX) enzymes, primarily in the central nervous system, to reduce pain perception and fever.
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 an opioid analgesic is appropriate
Relief of moderate to moderately severe pain
1-2 tablets (oxycodone 5-10 mg/acetaminophen 325-650 mg) orally every 4-6 hours as needed for pain; maximum acetaminophen 4000 mg/day (3000 mg/day in high-risk patients).
50-100 mg orally every 4-6 hours as needed; maximum 400 mg/day.
Oxycodone: 3-5 hours (immediate-release); prolonged in hepatic/renal impairment. Acetaminophen: 2-3 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 primarily metabolized by CYP3A4 and to a lesser extent by CYP2D6; acetaminophen is metabolized via conjugation (glucuronidation and sulfation) and by CYP2E1 (minor, but produces toxic 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.
Primarily renal (90% as glucuronide conjugates, <10% unchanged). Biliary/fecal excretion is minor (<5%).
Approximately 70% renal (unchanged drug and metabolites), 20% biliary/fecal, 10% other.
Oxycodone: 45-50% (primarily albumin). Acetaminophen: 10-25% (minimal).
Approximately 95% bound to plasma albumin and alpha-1-acid glycoprotein.
Oxycodone: 2.6 L/kg; large Vd indicates extensive tissue distribution.
0.2-0.4 L/kg, indicating limited extravascular distribution primarily confined to plasma and interstitial fluid.
Oral oxycodone: 60-87%; Acetaminophen: 75-85%.
Oral: 80-90%; Intramuscular: 90-100%; Rectal: 70-80%.
e GFR 30-60 m L/min: reduce dose to 50-75% of usual. e GFR 10-29 m L/min: reduce dose to 25-50% of usual. e GFR <10 m L/min: avoid use or use with extreme caution; reduce dose to 25% and extend dosing interval to every 8-12 hours.
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 necessary. Child-Pugh Class B: reduce starting dose by 50% (e.g., oxycodone 2.5-5 mg) and monitor. Child-Pugh Class C: avoid use or use with extreme caution; reduce dose to 25% and extend interval.
Child-Pugh A: no adjustment; Child-Pugh B: 50% dose reduction; Child-Pugh C: avoid use.
Weight-based: oxycodone 0.05-0.15 mg/kg per dose, acetaminophen 10-15 mg/kg per dose, orally every 4-6 hours as needed; maximum acetaminophen 75 mg/kg/day (not to exceed 4000 mg/day) in children ≥12 years; for children <12 years, max acetaminophen 75 mg/kg/day (max 325 mg per dose in children <6 years).
1-2 mg/kg/dose orally every 6 hours; maximum 6 mg/kg/day.
Start with lowest available dose (oxycodone 2.5-5 mg); consider extended dosing interval (every 6-8 hours); monitor renal and hepatic function; avoid in patients with advanced liver disease or GFR <30 m L/min.
Initiate at 25 mg every 6 hours; increase cautiously; monitor renal function.
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 associated with acetaminophen.
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; increased intracranial pressure; severe hypotension; hepatotoxicity (acetaminophen); opioid-induced hyperalgesia; adrenal insufficiency; severe hypotension; risks of use in patients with gastrointestinal obstruction; seizures; severe renal impairment.
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 hypersensitivity to oxycodone, acetaminophen, or any component; suspected or known gastrointestinal obstruction (e.g., paralytic ileus); severe hepatic impairment.
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 consumption as it increases the risk of hepatotoxicity from acetaminophen and enhances CNS depression from oxycodone. Grapefruit juice may potentiate oxycodone effects by inhibiting CYP3A4 metabolism; avoid concurrent use. High-fat meals may delay absorption of oxycodone but no specific food restrictions otherwise.
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 D (FDA). First trimester: Risk of neural tube defects and congenital anomalies with chronic use; no adequate studies. Second trimester: Continued risk of fetal dependence and withdrawal; growth restriction possible. Third trimester: High risk of neonatal opioid withdrawal syndrome (NOWS), respiratory depression, and preterm birth; avoid prolonged use.
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; M/P ratio ~3.4 (for oxycodone). Relative infant dose 1.7-6.8% of maternal weight-adjusted dose; may cause infant sedation, respiratory depression, and withdrawal. Use with caution, monitor infant for somnolence and feeding difficulties; avoid if mother is on high doses or has CYP2D6 ultra-rapid metabolizer status.
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.
Increased hepatic clearance and volume of distribution in pregnancy may require dose adjustments. No specific guidelines; consider using lowest effective dose and short-term therapy. Taper if discontinuing to prevent withdrawal. Avoid in labor due to neonatal respiratory depression; reserve for severe pain.
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 contains oxycodone (an opioid agonist) and acetaminophen. Always assess pain severity and opioid tolerance before prescribing. Monitor for respiratory depression, especially in opioid-naive patients. The maximum daily acetaminophen dose is 4 g (consider hepatic impairment and alcohol use). Avoid concurrent use of other acetaminophen-containing products. Prescribe naloxone for patients at risk of overdose. Use with caution in elderly, renal impairment, and respiratory conditions.
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.,This medication can cause drowsiness or dizziness; avoid driving or operating machinery until you know how you react.,Do not consume alcohol or other central nervous system depressants (e.g., benzodiazepines) while taking this medication.,Risk of dependence; do not share this medication with others. Store securely out of reach of children and pets.,Dispose of unused medication via a drug take-back program or mix with unpalatable substances and seal in a plastic bag before discarding.,Contact your doctor if you experience signs of allergic reaction (rash, itching, swelling), severe constipation, nausea/vomiting, or difficulty breathing.,Avoid taking other acetaminophen-containing products; do not exceed 4,000 mg of acetaminophen per day.
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 vs ANEXSIA, answered by our medical review team.
ROXICET is a Opioid Analgesic Combination that works by Roxicet is a combination of oxycodone, a full mu-opioid receptor agonist, and acetaminophen, which inhibits cyclooxygenase (COX) enzymes, primarily in the central nervous system, to reduce pain perception and fever.. 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 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 is: 1-2 tablets (oxycodone 5-10 mg/acetaminophen 325-650 mg) orally every 4-6 hours as needed for pain; maximum acetaminophen 4000 mg/day (3000 mg/day in high-risk patients).. 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 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 is classified as Category C. Pregnancy Category D (FDA). First trimester: Risk of neural tube defects and congenital anomalies with chronic use; no adequate studies. Second trimester: Continued risk of fetal d. 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.