Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
OXYCET 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
Oxycodone is a full opioid agonist with relative selectivity for the mu-opioid receptor, though it can interact with other opioid receptors at higher doses. The principal therapeutic action of oxycodone is analgesia. Acetaminophen is believed to produce analgesia through central action, possibly mediated through inhibition of cyclooxygenase (COX) and activation of descending serotonergic pathways, though the exact mechanism is not fully understood.
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.
Management of moderate to moderately severe pain where an opioid analgesic is appropriate,Off-label use: Relief of pain in various conditions including postoperative pain, traumatic pain, and chronic pain
Management of moderate to moderately severe pain where treatment with an opioid is appropriate and for which alternative treatments are inadequate
1 tablet (325 mg acetaminophen and 5 mg oxycodone) orally every 4 to 6 hours as needed for pain; maximum 12 tablets per 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).
The terminal elimination half-life of oxycodone is approximately 3.5-4 hours for immediate-release formulations. For controlled-release formulations, the half-life is similar due to absorption-limited elimination, but the duration of action is extended due to the formulation. In elderly patients or those with hepatic impairment, half-life may be increased up to 2-fold.
Hydrocodone: 3.8-4.5 hours (immediate-release). Acetaminophen: 2-3 hours. Clinical note: Half-life prolonged in hepatic impairment; requires dose adjustment.
Oxycodone is extensively metabolized in the liver via cytochrome P450 3A4 (CYP3A4) and CYP2D6 to noroxycodone, oxymorphone, and noroxymorphone. Acetaminophen is primarily metabolized in the liver via conjugation (glucuronidation and sulfation) and, to a lesser extent, via CYP2E1 to a toxic metabolite (NAPQI) which is normally detoxified by glutathione.
Hydrocodone: CYP3A4 and CYP2D6; Acetaminophen: primarily via glucuronidation (UGT1A1, UGT1A6, UGT1A9) and sulfation, with minor oxidation by CYP2E1.
Oxycodone is primarily metabolized in the liver via CYP3A4 to noroxycodone and via CYP2D6 to oxymorphone. Renal excretion accounts for approximately 87% of the administered dose, with 8.1% as unchanged oxycodone, 22.8% as noroxycodone, 9.1% as noroxymorphone, 3.2% as oxymorphone, and others. Fecal excretion is about 10%.
Renal: ~90-100% as hydrocodone metabolites (conjugated) and unchanged hydrocodone; ~60% as acetaminophen metabolites (glucuronide, sulfate, cysteine); <5% unchanged acetaminophen. Biliary/fecal: <5%.
Approximately 45% bound to plasma proteins, primarily albumin.
Hydrocodone: ~20-30% (albumin). Acetaminophen: ~10-25% (albumin).
Volume of distribution is 2.6-3.6 L/kg. This indicates extensive tissue distribution, with oxycodone widely distributed throughout body fluids and tissues, including the brain.
Hydrocodone: 3-4 L/kg (extensive tissue distribution). Acetaminophen: ~1 L/kg (uniformly distributed).
Oral immediate-release: 60-87% due to first-pass metabolism. Extended-release: approximately the same as immediate-release when adjusted for dose. Intravenous: 100%. Rectal: similar to oral (60-87%).
Oral: Hydrocodone ~70% (high first-pass metabolism); Acetaminophen ~85-90% (minimal first-pass).
For 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: not recommended due to risk of oxycodone accumulation.
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% or extend dosing interval; Child-Pugh C: contraindicated or use with extreme caution, maximum 50% of normal dose.
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 recommended for children under 18 years due to risk of respiratory depression; for older adolescents (≥18 years), adult dosing may be considered.
Not recommended for pediatric patients; safety and efficacy not established for children under 18 years. For adolescents ≥18 years: adult dosing.
Initiate at lowest effective dose, typically one-half of adult dose (one tablet every 6 hours) and titrate slowly; caution due to increased sensitivity and risk of falls and respiratory depression.
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.
Addiction, Abuse, and Misuse: Oxycodone exposes users to risks of addiction, abuse, and misuse, which can lead to overdose and death. Assess each patient's risk before prescribing, and monitor regularly for development of these behaviors or conditions. Life-Threatening Respiratory Depression: Serious, life-threatening, or fatal respiratory depression may occur. Monitor closely, especially upon initiation or following a dose increase. Accidental Ingestion: Accidental ingestion of even one dose of oxycodone, especially by children, can result in a fatal overdose of oxycodone. Neonatal Opioid Withdrawal Syndrome: Prolonged use during pregnancy can result in neonatal opioid withdrawal syndrome, which may be life-threatening if not recognized and treated. Risks from Concomitant Use with Benzodiazepines or Other CNS Depressants: Concomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants may result in profound sedation, respiratory depression, coma, and death. Reserve for use in patients for whom alternative treatment options are inadequate. Hepatotoxicity: Acetaminophen has been associated with cases of acute liver failure, at times resulting in liver transplant and death. Most of the cases of liver injury are associated with the use of acetaminophen at doses exceeding 4000 mg per day, and often involve more than one acetaminophen-containing product.
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.
Risk of addiction, abuse, and misuse,Life-threatening respiratory depression,Accidental ingestion (especially in children),Neonatal opioid withdrawal syndrome,Risks from concomitant use with benzodiazepines or other CNS depressants,Hepatotoxicity from acetaminophen,Severe hypotension,Gastrointestinal effects (e.g., constipation, ileus),Seizures in patients with seizure disorders,Serotonin syndrome with concomitant serotonergic drugs,Adrenal insufficiency,Use in patients with head injury or increased intracranial pressure,Use in patients with acute abdominal conditions
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 oxycodone or acetaminophen,Significant respiratory depression,Acute or severe bronchial asthma in an unmonitored setting or in absence of resuscitative equipment,Paralytic ileus,Severe hepatic impairment (for acetaminophen component),Concurrent use of monoamine oxidase inhibitors (MAOIs) or within 14 days of such therapy
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 alcohol. Grapefruit juice may increase oxycodone levels (monitor for opioid effects); high-fat meals may delay absorption but not total exposure. No other significant dietary restrictions.
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.
Oxycodone/paracetamol (OXYCET). Oxycodone: FDA Category B (but Category D if prolonged use or near term). First trimester: Increased risk of neural tube defects, congenital heart defects; limited data, but avoid if possible. Second and third trimesters: Prolonged use may cause fetal dependence, withdrawal syndrome; near term, neonatal respiratory depression. Paracetamol: Category B; appears safe in standard doses but overdose causes fetal hepatotoxicity.
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.
Oxycodone is excreted into breast milk; relative infant dose approximately 1.6-3.5% of maternal weight-adjusted dose. M/P ratio not firmly established. Use caution; monitor infant for sedation, respiratory depression, poor feeding. Paracetamol is safe; excreted in low levels. If prolonged maternal oxycodone use, risk of neonatal withdrawal.
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.
Oxycodone distribution volume increases in pregnancy; clearance may increase, potentially requiring higher doses to achieve analgesic efficacy, but no standard adjustment. Avoid chronic use; use lowest effective dose shortest duration. Paracetamol dose 650-1000 mg every 4-6 hours; max 4000 mg/day; no pregnancy-specific dose adjustment unless hepatic impairment.
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.
Oxycet is a combination of oxycodone and acetaminophen. Maximum acetaminophen daily dose is 4 g; in chronic alcohol use or hepatic impairment, limit to 2 g. Use with caution in elderly, respiratory compromise, or history of substance abuse. Constipation prophylaxis (e.g., stool softener) is recommended. Avoid concurrent use with other CNS depressants. Monitor for signs of tolerance, dependence, and misuse.
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 exactly as prescribed. Do not increase dose or frequency without consulting your doctor.,Do not combine with other products containing acetaminophen (e.g., Tylenol) to avoid exceeding 4000 mg per day.,Avoid alcohol while taking this medication; it increases the risk of liver damage and sedation.,This drug can cause drowsiness or dizziness; do not drive or operate heavy machinery until you know how it affects you.,Constipation is common; increase fluid and fiber intake, and consider using a stool softener as recommended.,Do not stop taking suddenly; your doctor will guide you on tapering to prevent withdrawal symptoms.,Store securely out of reach of others; unused medication should be disposed of properly.
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 OXYCET vs ANEXSIA 7.5/325, answered by our medical review team.
OXYCET is a Opioid Analgesic Combination that works by Oxycodone is a full opioid agonist with relative selectivity for the mu-opioid receptor, though it can interact with other opioid receptors at higher doses. The principal therapeutic action of oxycodone is analgesia. Acetaminophen is believed to produce analgesia through central action, possibly mediated through inhibition of cyclooxygenase (COX) and activation of descending serotonergic pathways, though the exact mechanism is not fully understood.. 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 OXYCET and ANEXSIA 7.5/325 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 OXYCET is: 1 tablet (325 mg acetaminophen and 5 mg oxycodone) orally every 4 to 6 hours as needed for pain; maximum 12 tablets per 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 OXYCET 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. OXYCET is classified as Category C. Oxycodone/paracetamol (OXYCET). Oxycodone: FDA Category B (but Category D if prolonged use or near term). First trimester: Increased risk of neural tube defects, congenital heart d. 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.