Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
DARVOCET vs ANEXSIA 7.5/650
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 mu-opioid receptor agonist that inhibits ascending pain pathways and alters pain perception; acetaminophen inhibits cyclooxygenase (COX) enzymes, primarily in the CNS, reducing prostaglandin synthesis and fever.
FDA-approved: relief of mild to moderate pain,Off-label: none commonly recognized
Management of acute pain severe enough to require an opioid analgesic and for which alternative treatments are inadequate
1 tablet (propoxyphene 100 mg / acetaminophen 650 mg) orally every 4 hours as needed for pain; maximum 6 tablets per day.
1 tablet orally every 4 to 6 hours as needed; maximum 6 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.
Hydrocodone: Terminal half-life 3.8-7.2 hours (mean 5.6 h). Acetaminophen: 1.5-2.5 hours (therapeutic) but prolonged to >4 hours in overdose with hepatotoxicity risk.
Propoxyphene: extensively metabolized via CYP3A4 to norpropoxyphene (active metabolite); Acetaminophen: metabolized primarily via glucuronidation and sulfation, with minor CYP2E1 oxidation.
Hydrocodone: CYP3A4 and CYP2D6; acetaminophen: primarily liver glucuronidation (UGT1A1, UGT1A6, UGT1A9) and sulfation (SULT1A1, SULT1A3), with minor CYP2E1 oxidation.
Propoxyphene: primarily hepatic metabolism to norpropoxyphene, renal excretion of metabolites (<1% unchanged). Acetaminophen: renal excretion of conjugates (85-90%) and unchanged drug (2-4%).
Hydrocodone: Renal elimination of metabolites (hydromorphone, norhydrocodone) and unchanged drug accounts for ~60-90% of clearance. Acetaminophen: ~85% of dose is excreted in urine as glucuronide and sulfate conjugates; 5-10% unchanged; 2-5% as mercapturate.
Propoxyphene: 80% bound to albumin. Acetaminophen: 10-25% bound to albumin.
Hydrocodone: ~36% bound to serum proteins. Acetaminophen: 10-25% bound (minimal binding).
Propoxyphene: 10-16 L/kg (large due to lipophilicity). Acetaminophen: 0.9-1.0 L/kg (distributes evenly in body fluids).
Hydrocodone: Vd ~3-5 L/kg (wide distribution). Acetaminophen: Vd ~0.9-1.0 L/kg (primarily body water).
Propoxyphene: oral bioavailability ~40% due to first-pass metabolism. Acetaminophen: oral bioavailability 80-90%.
Oral: Hydrocodone ~70-80% (variable first-pass). Acetaminophen ~63-89% (mean 75-80%).
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.
Cr Cl <30 m L/min: contraindicated; Cr Cl 30-60 m L/min: maximum 3 tablets per day; given the hydrocodone component, avoid in severe renal impairment.
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 Class A: no adjustment; Child-Pugh Class B: reduce dose by 50% and monitor; Child-Pugh Class C: contraindicated due to hydrocodone.
Not recommended for pediatric use due to risk of serious adverse effects; safety and efficacy not established.
Not recommended in pediatric patients due to risk of respiratory depression; for ages <18, contraindicated.
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.
Initiate with lowest effective dose, monitor for respiratory depression and constipation; maximum 4 tablets per day in patients >65 years.
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 (especially in children) can be fatal; neonatal opioid withdrawal syndrome; cytochrome P450 3A4 interaction (concomitant use with CYP3A4 inhibitors may increase hydrocodone levels); risk of medication errors (confusion between different strengths).
Respiratory depression, QT prolongation (propoxyphene), hepatotoxicity (acetaminophen at high doses), abuse potential, interaction with alcohol and CNS depressants.
Addiction, abuse, and misuse; respiratory depression; neonatal opioid withdrawal syndrome; interactions with CNS depressants; risk of serotonin syndrome with serotonergic drugs; adrenal insufficiency; hypotension; seizures; gastrointestinal obstruction; severe cutaneous reactions (acetaminophen); hepatotoxicity (acetaminophen overdose); acute abdominal conditions; impaired mental/physical abilities; elderly/debilitated patients; renal/hepatic impairment.
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.
Significant respiratory depression; acute or severe bronchial asthma (without monitoring or resuscitative equipment); known or suspected gastrointestinal obstruction (including paralytic ileus); hypersensitivity to hydrocodone or acetaminophen; use with MAOIs or within 14 days of such therapy.
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 due to increased risk of acetaminophen hepatotoxicity and additive CNS depression. Grapefruit juice may increase hydrocodone absorption; consider avoiding. No other significant food interactions.
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.
FDA Category C. First trimester: Possible increased risk of cardiac defects with oxycodone. Second/third trimester: Chronic use may lead to neonatal opioid withdrawal syndrome; no clear teratogenicity. Acetaminophen is generally safe, but high doses may be hepatotoxic.
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.
Oxycodone: M/P ratio ~0.8-3; present in milk; risk of neonatal sedation. Acetaminophen: M/P ~0.8-1, low risk. Avoid due to oxycodone; consider alternative analgesic.
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 of oxycodone in pregnancy may require increased dose; acetaminophen pharmacokinetics unchanged. Adjust based on pain control and withdrawal risk.
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.
Fixed-dose combination of hydrocodone bitartrate (7.5 mg) and acetaminophen (650 mg). Hydrocodone is a schedule II controlled substance with high abuse potential. Acetaminophen hepatotoxicity risk increases above 3 g/day; prescribe no more than 4 doses per day. Monitor for respiratory depression, especially in opioid-naïve patients. Avoid in severe hepatic impairment. Use with caution in patients with COPD, sleep apnea, or concurrent CNS depressants. Consider naloxone co-prescription if high opioid dose or concurrent benzodiazepine use.
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.,Do not take with alcohol or other medications containing acetaminophen.,May cause drowsiness or dizziness; avoid driving or operating machinery until effects are known.,Store securely out of reach of children and others; dispose of unused tablets properly.,Seek emergency care for difficulty breathing, severe sedation, or signs of allergic reaction.,Do not abruptly stop after prolonged use; withdrawal symptoms may occur.
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 7.5/650, 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 7.5/650 is a Opioid Analgesic Combination that works by Hydrocodone is a mu-opioid receptor agonist that inhibits ascending pain pathways and alters pain perception; acetaminophen inhibits cyclooxygenase (COX) enzymes, primarily in the CNS, reducing prostaglandin synthesis and fever.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between DARVOCET and ANEXSIA 7.5/650 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 7.5/650 is: 1 tablet orally every 4 to 6 hours as needed; 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 DARVOCET and ANEXSIA 7.5/650 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 7.5/650 is classified as Category C. FDA Category C. First trimester: Possible increased risk of cardiac defects with oxycodone. Second/third trimester: Chronic use may lead to neonatal opioid withdrawal syndrome; no . Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.