Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
DARVOCET vs ANEXSIA 5/325
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Darvocet is a combination of propoxyphene, a mu-opioid receptor agonist that alters perception of and response to pain, and acetaminophen, which inhibits COX enzymes and modulates descending serotonergic pathways.
Hydrocodone is a semi-synthetic opioid agonist that binds to mu-opioid receptors in the CNS, inhibiting ascending pain pathways and altering pain perception. Acetaminophen is a para-aminophenol derivative with analgesic and antipyretic effects, primarily through central COX-2 inhibition and activation of descending serotonergic pathways.
FDA-approved: relief of mild to moderate pain,Off-label: none commonly recognized
Management of moderate to moderately severe pain where an opioid analgesic is appropriate
1 tablet (propoxyphene 100 mg / acetaminophen 650 mg) orally every 4 hours as needed for pain; maximum 6 tablets per day.
1-2 tablets orally every 4-6 hours as needed for pain; maximum 8 tablets per day.
Propoxyphene: 6-12 hours (parent), 30-36 hours (norpropoxyphene). Acetaminophen: 1-4 hours (therapeutic doses). Accumulation of norpropoxyphene occurs with repeated dosing.
Oxycodone: terminal half-life 3.2-4.3 hours (immediate-release); prolonged in hepatic impairment. Acetaminophen: terminal half-life 2-3 hours (therapeutic doses); prolonged in hepatic impairment or overdose.
Propoxyphene: extensively metabolized via CYP3A4 to norpropoxyphene (active metabolite); Acetaminophen: metabolized primarily via glucuronidation and sulfation, with minor CYP2E1 oxidation.
Hydrocodone: primarily hepatic via CYP3A4 and CYP2D6 to active metabolites (hydromorphone). Acetaminophen: hepatic metabolism via conjugation (glucuronidation, sulfation) and CYP2E1-mediated oxidation to toxic NAPQI.
Propoxyphene: primarily hepatic metabolism to norpropoxyphene, renal excretion of metabolites (<1% unchanged). Acetaminophen: renal excretion of conjugates (85-90%) and unchanged drug (2-4%).
Oxycodone: renal excretion of metabolites (conjugated and unconjugated) and parent drug; ~10% excreted unchanged. Acetaminophen: renal excretion of metabolites (glucuronide and sulfate conjugates); ~2-4% excreted unchanged.
Propoxyphene: 80% bound to albumin. Acetaminophen: 10-25% bound to albumin.
Oxycodone: 38-45% bound to albumin and alpha-1-acid glycoprotein. Acetaminophen: 10-25% bound to albumin at therapeutic concentrations.
Propoxyphene: 10-16 L/kg (large due to lipophilicity). Acetaminophen: 0.9-1.0 L/kg (distributes evenly in body fluids).
Oxycodone: Vd 2.0-3.0 L/kg; distributes extensively into tissues. Acetaminophen: Vd 0.8-1.0 L/kg; relatively uniform distribution.
Propoxyphene: oral bioavailability ~40% due to first-pass metabolism. Acetaminophen: oral bioavailability 80-90%.
Oxycodone: oral bioavailability 60-87% (immediate-release). Acetaminophen: oral bioavailability 88-98% (therapeutic doses).
For creatinine clearance <50 m L/min: avoid use; propoxyphene accumulates causing CNS and cardiac toxicity. For 50–80 m L/min: reduce frequency to every 6 hours. Not recommended in ESRD or dialysis.
GFR 30-50 m L/min: use with caution, increase dosing interval to every 6 hours; GFR <30 m L/min: avoid use due to hydrocodeone accumulation.
Child-Pugh Class A: cautious use, reduce dose by 50% and monitor. Child-Pugh Class B or C: contraindicated due to risk of hepatotoxicity from acetaminophen and altered propoxyphene metabolism.
Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50% and monitor; Child-Pugh C: contraindicated.
Not recommended for pediatric use due to risk of serious adverse effects; safety and efficacy not established.
Not recommended for children under 18 years due to risk of respiratory depression.
Start with 1 tablet (100/650 mg) every 6 hours; maximum 4 tablets per day. Avoid in patients with renal impairment or multiple comorbidities. Increased risk of CNS depression and falls.
Start with lowest dose (1 tablet every 6 hours), monitor renal and hepatic function, and avoid in frail elderly due to increased fall and cognitive impairment risk.
Propoxyphene has been withdrawn from the US market due to risk of fatal overdose; Darvocet is no longer available in the US.
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; and hepatotoxicity from acetaminophen overdose.
Respiratory depression, QT prolongation (propoxyphene), hepatotoxicity (acetaminophen at high doses), abuse potential, interaction with alcohol and CNS depressants.
Risk of opioid 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; adrenal insufficiency; severe hypotension; gastrointestinal obstruction; seizure; and serotonin syndrome.
Hypersensitivity to propoxyphene or acetaminophen, severe asthma or respiratory depression, known CYP3A4 inhibitors (risk of increased propoxyphene levels), concurrent use of alcohol or other CNS depressants.
Hypersensitivity to hydrocodone or acetaminophen; significant respiratory depression; acute or severe bronchial asthma; GI obstruction; known or suspected paralytic ileus; severe hepatic impairment; and concurrent use of MAOIs within 14 days.
Avoid alcohol. No specific food interactions, but take with food if gastrointestinal upset occurs. Maintain adequate hydration and fiber intake to prevent constipation.
Avoid alcohol. Grapefruit juice may enhance side effects; limit intake. Take with food to reduce gastrointestinal discomfort.
Pregnancy Category C. First trimester: No evidence of structural malformations from acetaminophen; propoxyphene has not been associated with increased risk of major birth defects. Second and third trimesters: Chronic use may lead to neonatal withdrawal syndrome (irritability, hypertonia, tremors) and respiratory depression. High-dose or prolonged use near term associated with neonatal respiratory depression.
First trimester: Associated with increased risk of neural tube defects and cardiovascular malformations; avoid use. Second and third trimesters: Chronic exposure may cause fetal renal toxicity, oligohydramnios, and premature closure of ductus arteriosus. Use only if clearly needed.
Excreted in breast milk. Acetaminophen: M/P ratio 0.9-1.4; low infant dose. Propoxyphene: M/P ratio ~0.5; estimated infant dose <1% of maternal weight-adjusted dose. Considered compatible with breastfeeding if used short-term; monitor infant for drowsiness, poor feeding.
Paracetamol and hydrocodone are excreted in breast milk. M/P ratio: paracetamol ~1.0, hydrocodone ~1.0-2.0. Use with caution; monitor infant for drowsiness and respiratory depression. Consider risk of infant sedation with long-term use.
No standard dose adjustment recommended. Increased clearance of acetaminophen in pregnancy may require higher doses for efficacy; avoid exceeding 4 g/day. Propoxyphene pharmacokinetics not significantly altered; avoid prolonged use due to accumulation risk.
Increased clearance in pregnancy may require dose adjustment. Monitor for pain control and adverse effects; no fixed dose change recommended. Consider lower starting dose due to potential fetal risks. Avoid chronic use; taper if possible.
Darvocet contains propoxyphene, a weak opioid with potential for cardiac toxicity (QT prolongation) at high doses. Avoid in patients with history of substance abuse, suicidal ideation, or concurrent use of CNS depressants. Efficacy similar to aspirin, but with higher risk of adverse effects; consider safer alternatives. Monitor for respiratory depression in elderly or debilitated patients.
ANEXSIA 5/325 contains hydrocodone 5 mg and acetaminophen 325 mg. Maximum acetaminophen dose from all sources should not exceed 4 g/day in adults; avoid in severe hepatic impairment. Hydrocodone is a Schedule II controlled substance with abuse potential; monitor for respiratory depression, especially in opioid-naive patients. Use with caution in patients with COPD, sleep apnea, or increased intracranial pressure. Consider naloxone co-prescription for high-risk patients. For acute pain, limit duration to 3-7 days.
Take exactly as prescribed; do not take more than recommended dose.,Avoid alcohol and other CNS depressants (e.g., benzodiazepines) as they increase risk of serious side effects.,Do not drive or operate heavy machinery until you know how this medication affects you.,Do not stop abruptly; withdrawal may occur. Taper under medical supervision.,Report severe constipation, difficulty breathing, or signs of allergic reaction.,Store securely away from children and others; dispose properly when no longer needed.
Take exactly as prescribed; do not increase dose or frequency without consulting your doctor.,Do not consume alcohol or other sedatives (e.g., benzodiazepines) while taking this medication.,Avoid other products containing acetaminophen (e.g., Tylenol, cold remedies) to prevent liver damage.,This medication may cause drowsiness or dizziness; do not drive or operate machinery until you know how it affects you.,Store securely out of reach of others; dispose of unused medication via drug take-back programs.,Seek emergency help if you have trouble breathing, severe drowsiness, or signs of allergic reaction.
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 DARVOCET vs ANEXSIA 5/325, answered by our medical review team.
DARVOCET is a Opioid Analgesic Combination that works by Darvocet is a combination of propoxyphene, a mu-opioid receptor agonist that alters perception of and response to pain, and acetaminophen, which inhibits COX enzymes and modulates descending serotonergic pathways.. ANEXSIA 5/325 is a Opioid Analgesic Combination that works by Hydrocodone is a semi-synthetic opioid agonist that binds to mu-opioid receptors in the CNS, inhibiting ascending pain pathways and altering pain perception. Acetaminophen is a para-aminophenol derivative with analgesic and antipyretic effects, primarily through central COX-2 inhibition and activation of descending serotonergic pathways.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between DARVOCET and ANEXSIA 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 DARVOCET is: 1 tablet (propoxyphene 100 mg / acetaminophen 650 mg) orally every 4 hours as needed for pain; maximum 6 tablets per day.. The standard adult dose of ANEXSIA 5/325 is: 1-2 tablets orally every 4-6 hours as needed for pain; maximum 8 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 DARVOCET and ANEXSIA 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. DARVOCET is classified as Category C. Pregnancy Category C. First trimester: No evidence of structural malformations from acetaminophen; propoxyphene has not been associated with increased risk of major birth defects. . ANEXSIA 5/325 is classified as Category C. First trimester: Associated with increased risk of neural tube defects and cardiovascular malformations; avoid use. Second and third trimesters: Chronic exposure may cause fetal re. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.