Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
OXYCONTIN vs DARVOCET A500
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, although it can bind to other opioid receptors at higher doses. The principal therapeutic action of oxycodone is analgesia. Like all full opioid agonists, there is no ceiling effect for analgesia with oxycodone. Clinically, dosage is titrated to provide adequate analgesia and may be limited by adverse reactions, including respiratory and CNS depression.
Combination analgesic: acetaminophen inhibits cyclooxygenase (COX) and modulates endocannabinoid system; propoxyphene is a mu-opioid receptor agonist.
Management of pain severe enough to require daily, around-the-clock, long-term opioid treatment and for which alternative treatment options are inadequate,Off-label: Treatment of opioid dependence (as part of substitution therapy)
Mild to moderate pain
10 mg orally every 12 hours; titrate based on pain severity and prior opioid exposure.
One tablet (500 mg acetaminophen, 100 mg propoxyphene napsylate) orally every 4 hours as needed for pain; maximum 6 tablets per day.
4.5-5.0 hours (immediate-release); controlled-release OXYCONTIN has an apparent half-life of 4.5-8.7 hours. Terminal half-life is ~3.5-4 hours for immediate-release, reflecting context-sensitive elimination.
Propoxyphene: 6-12 hours (terminal, prolonged in elderly, hepatic impairment, or overdose). Acetaminophen: 2-3 hours (terminal, prolonged in hepatic impairment or overdose).
Oxycodone is metabolized primarily via CYP3A4 to noroxycodone (major metabolite) and via CYP2D6 to oxymorphone (minor metabolite). Both metabolites are active, with oxymorphone having higher potency. Oxycodone and its metabolites are conjugated and excreted in urine.
Propoxyphene: hepatic via CYP3A4 and CYP2D6; active metabolite norpropoxyphene. Acetaminophen: hepatic via conjugation (glucuronidation, sulfation) and CYP2E1.
Primarily renal (90% as metabolites, 10% unchanged). Also biliary/fecal (10%).
Propoxyphene: ~20-25% renal as unchanged drug, ~35% as norpropoxyphene, ~20% biliary/fecal. Acetaminophen: ~2-4% renal unchanged, ~85% as glucuronide and sulfate conjugates, ~5% as cysteine and mercapturate conjugates.
38-45%, primarily bound to albumin.
Propoxyphene: ~78% bound to albumin. Acetaminophen: 10-25% bound (minimal).
2.6-3.0 L/kg. Extensive tissue distribution, high Vd indicates penetration into peripheral tissues.
Propoxyphene: 16 L/kg (extensive tissue distribution). Acetaminophen: 0.9 L/kg.
Oral immediate-release: 60-87% (first-pass metabolism). Oral extended-release (Oxy Contin): 60-87% (similar). Intravenous: 100%.
Propoxyphene: 30-70% (first-pass metabolism). Acetaminophen: ~88% (oral).
Cr Cl 30-60 m L/min: reduce dose by 25%; Cr Cl <30 m L/min: reduce dose by 50% and administer every 12 hours; hemodialysis: avoid use.
Contraindicated in severe renal impairment (Cr Cl <30 m L/min). For GFR 30-50 m L/min: reduce dose to 1 tablet every 6 hours. Monitor for propoxyphene accumulation.
Child-Pugh Class A: no adjustment; Child-Pugh Class B: reduce dose by 50%; Child-Pugh Class C: avoid use.
Avoid use in Child-Pugh class C (severe hepatic impairment). In Child-Pugh class A or B: use with caution, reduce dose by 50% (e.g., 1 tablet every 6-8 hours), and avoid chronic use due to acetaminophen toxicity risk.
Not approved for pediatric patients <18 years; for children ≥11 years (opioid-tolerant): 0.2 mg/kg orally every 12 hours, titrate; maximum single dose 10 mg.
Not recommended for pediatric use due to safety concerns (propoxyphene associated with respiratory depression in children). For adolescents >12 years: 1 tablet every 4 hours as needed; maximum 6 tablets/day.
Initiate at 5 mg orally every 12 hours; titrate cautiously; monitor for respiratory depression and constipation.
Start at 1 tablet every 6-8 hours; avoid exceeding 4 tablets/day. Monitor for CNS depression, constipation, and falls. Consider decreased hepatic/renal function and increased sensitivity.
WARNING: ADDICTION, ABUSE, AND MISUSE; LIFE-THREATENING RESPIRATORY DEPRESSION; ACCIDENTAL INGESTION; NEONATAL OPIOID WITHDRAWAL SYNDROME; and RISKS FROM CONCOMITANT USE WITH BENZODIAZEPINES OR OTHER CNS DEPRESSANTS
Propoxyphene is associated with fatal respiratory depression, abuse potential, and risk of overdose; contraindicated in patients with suicidal ideation or addiction.
Addiction, abuse, and misuse: Oxy Contin exposes patients and other users to the risks of opioid addiction, abuse, and misuse, which can lead to overdose and death. Assess each patient's risk prior to prescribing, and monitor all patients regularly for the development of these behaviors or conditions.,Life-threatening respiratory depression: Serious, life-threatening, or fatal respiratory depression may occur. Monitor for respiratory depression, especially during initiation of therapy or following a dose increase. Instruct patients to swallow tablets whole; crushing, chewing, or dissolving can cause rapid release and absorption of a potentially fatal dose.,Accidental ingestion: Accidental ingestion of even one dose of Oxy Contin, especially by children, can result in a fatal overdose of oxycodone.,Neonatal opioid withdrawal syndrome: Prolonged use of Oxy Contin during pregnancy can result in withdrawal in the neonate. Neonatal opioid withdrawal syndrome, unlike opioid withdrawal in adults, 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 CNS depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. Reserve concomitant prescribing for use in patients for whom alternative treatment options are inadequate.
Risk of respiratory depression, abuse and dependence, cardiac toxicity (QT prolongation, arrhythmias), acetaminophen hepatotoxicity, increased seizure risk in patients with CNS depression, interaction with CNS depressants.
Significant respiratory depression,Acute or severe bronchial asthma in an unmonitored setting or in the absence of resuscitative equipment,Known or suspected gastrointestinal obstruction, including paralytic ileus,Hypersensitivity (e.g., anaphylaxis) to oxycodone or any other components of the product
Hypersensitivity to propoxyphene or acetaminophen, significant respiratory depression, acute or severe bronchial asthma, paralytic ileus, known CYP2D6 ultrarapid metabolizers, concomitant use of MAOIs or within 14 days, suicidal patients, addiction-prone individuals.
Avoid alcohol, which can increase oxycodone absorption and central nervous system depression. Grapefruit juice may alter oxycodone metabolism; limit or avoid consumption. No specific food restrictions, but high-fat meals may slow absorption slightly; take with or without food consistently.
Take with food to reduce gastrointestinal upset. Avoid grapefruit juice as it may increase propoxyphene absorption. Avoid alcohol entirely due to increased hepatotoxicity and CNS depression. High-fat meals may delay absorption of propoxyphene, but no specific restrictions.
FDA Pregnancy Category C prior to 2020; no adequate studies in pregnant women. First trimester: Limited data suggest possible increased risk of neural tube defects (1.8-fold) and oral clefts (1.5-fold) with opioid use, but confounded by underlying conditions. Second and third trimesters: Chronic use may cause fetal opioid dependence and neonatal abstinence syndrome (NAS); maternal withdrawal may precipitate preterm labor. Avoid prolonged use near term due to risk of neonatal respiratory depression.
First trimester: Propoxyphene crosses placenta, limited data; possible association with neural tube defects. Second trimester: Avoid; risk of fetal respiratory depression. Third trimester: Avoid; neonatal withdrawal syndrome (tremors, hypertonia) and respiratory depression at delivery.
Oxycodone is excreted into breast milk; relative infant dose is approximately 2.7–8.8% of maternal weight-adjusted dose. M/P ratio unknown. Monitor infant for sedation, respiratory depression, and poor feeding. American Academy of Pediatrics considers oxycodone compatible with breastfeeding with caution; avoid rapid accumulation in mothers with impaired metabolism (CYP2D6 poor metabolizers).
Propoxyphene and acetaminophen are excreted into breast milk. M/P ratio for propoxyphene ~0.5-1.0; low relative infant dose (~2% maternal). Acetaminophen M/P ~0.9. Use caution; monitor infant for sedation, poor feeding. AAP considers compatible.
Pregnancy increases oxycodone clearance by 1.3- to 2.5-fold due to enhanced hepatic metabolism (CYP3A4 and CYP2D6 induction) and increased renal blood flow. Dose adjustments may be necessary to maintain analgesia; clinical monitoring for pain control and withdrawal symptoms is essential. Titrate to effect; avoid abrupt discontinuation. Postpartum clearance returns to baseline over 1-2 weeks.
Pharmacokinetic changes: Increased renal clearance and volume of distribution may reduce propoxyphene levels; no established dose adjustment guidelines. Acetaminophen levels unchanged. Use lowest effective dose for shortest duration.
Oxy Contin is an extended-release formulation of oxycodone, indicated for around-the-clock pain management. Do not crush, chew, or break tablets, as this can lead to rapid release and fatal overdose. Use with caution in patients with respiratory compromise, head injury, or increased intracranial pressure. Monitor for signs of misuse, abuse, or addiction. Abrupt discontinuation may precipitate withdrawal; taper dose gradually. Constipation is common; consider prophylactic laxatives. Contraindicated in severe asthma, paralytic ileus, or hypersensitivity.
Darvocet A500 contains propoxyphene and acetaminophen. Propoxyphene is a weak mu-opioid agonist with high interindividual variability in metabolism. Avoid in patients with creatinine clearance <30 m L/min due to accumulation of norpropoxyphene, which can cause cardiac toxicity (QT prolongation, risk of fatal arrhythmias). Do not exceed 600 mg propoxyphene base (or equivalent) per day. Monitor liver function due to acetaminophen, especially in patients with hepatic impairment or chronic alcohol use. Use with caution in elderly due to increased fall risk and respiratory depression.
Take Oxy Contin exactly as prescribed, usually every 12 hours. Do not take more or less than directed.,Swallow the tablet whole with water. Do not crush, chew, or break the tablet, as this can cause a dangerous overdose.,Avoid alcohol and other central nervous system depressants (e.g., benzodiazepines, sedatives) as they increase the risk of severe sedation, respiratory depression, and death.,Do not stop taking Oxy Contin suddenly; ask your doctor how to safely discontinue the medication to avoid withdrawal symptoms.,Common side effects include constipation, nausea, drowsiness, and dizziness. Contact your doctor if you experience severe constipation, difficulty breathing, or signs of allergic reaction.,Store Oxy Contin in a secure place out of sight and reach of children and pets. Dispose of unused medication via a drug take-back program.,Do not drive or operate heavy machinery until you know how Oxy Contin affects you.,Inform all healthcare providers that you are taking Oxy Contin, especially before surgery or emergency treatment.
Take exactly as prescribed; do not increase dose or frequency without consulting your doctor.,Do not drink alcohol while taking this medication; it increases risk of liver damage and sedation.,Avoid driving or operating heavy machinery until you know how this drug affects you.,Do not take other medications containing acetaminophen to avoid exceeding the maximum daily dose (3000 mg).,Contact your doctor immediately if you experience irregular heartbeat, fainting, or severe dizziness.,Store at room temperature, away from moisture and heat, and out of reach of children.,Do not share this medication with others; it can cause serious harm or death.,If you miss a dose, skip it and resume your regular schedule; do not double the dose.
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 OXYCONTIN vs DARVOCET A500, answered by our medical review team.
OXYCONTIN is a Opioid Analgesic that works by Oxycodone is a full opioid agonist with relative selectivity for the mu-opioid receptor, although it can bind to other opioid receptors at higher doses. The principal therapeutic action of oxycodone is analgesia. Like all full opioid agonists, there is no ceiling effect for analgesia with oxycodone. Clinically, dosage is titrated to provide adequate analgesia and may be limited by adverse reactions, including respiratory and CNS depression.. DARVOCET A500 is a Opioid Analgesic Combination that works by Combination analgesic: acetaminophen inhibits cyclooxygenase (COX) and modulates endocannabinoid system; propoxyphene is a mu-opioid receptor agonist.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between OXYCONTIN and DARVOCET A500 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 OXYCONTIN is: 10 mg orally every 12 hours; titrate based on pain severity and prior opioid exposure.. The standard adult dose of DARVOCET A500 is: One tablet (500 mg acetaminophen, 100 mg propoxyphene napsylate) orally every 4 hours as needed for pain; 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 OXYCONTIN and DARVOCET A500 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. OXYCONTIN is classified as Category C. FDA Pregnancy Category C prior to 2020; no adequate studies in pregnant women. First trimester: Limited data suggest possible increased risk of neural tube defects (1.8-fold) and o. DARVOCET A500 is classified as Category C. First trimester: Propoxyphene crosses placenta, limited data; possible association with neural tube defects. Second trimester: Avoid; risk of fetal respiratory depression. Third tr. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.