Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
DARVOCET vs ANEXSIA 7.5/325
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 mu-opioid receptor agonist, producing analgesia and euphoria. Acetaminophen inhibits cyclooxygenase (COX) enzymes, reducing prostaglandin synthesis and providing analgesic and antipyretic effects.
FDA-approved: relief of mild to moderate pain,Off-label: none commonly recognized
Management of moderate to moderately severe pain where treatment with an opioid is appropriate 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 (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).
Propoxyphene: 6-12 hours (parent), 30-36 hours (norpropoxyphene). Acetaminophen: 1-4 hours (therapeutic doses). Accumulation of norpropoxyphene occurs with repeated dosing.
Hydrocodone: 3.8-4.5 hours (immediate-release). Acetaminophen: 2-3 hours. Clinical note: Half-life prolonged in hepatic impairment; requires dose adjustment.
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 via glucuronidation (UGT1A1, UGT1A6, UGT1A9) and sulfation, with minor oxidation by CYP2E1.
Propoxyphene: primarily hepatic metabolism to norpropoxyphene, renal excretion of metabolites (<1% unchanged). Acetaminophen: renal excretion of conjugates (85-90%) and unchanged drug (2-4%).
Renal: ~90-100% as hydrocodone metabolites (conjugated) and unchanged hydrocodone; ~60% as acetaminophen metabolites (glucuronide, sulfate, cysteine); <5% unchanged acetaminophen. Biliary/fecal: <5%.
Propoxyphene: 80% bound to albumin. Acetaminophen: 10-25% bound to albumin.
Hydrocodone: ~20-30% (albumin). Acetaminophen: ~10-25% (albumin).
Propoxyphene: 10-16 L/kg (large due to lipophilicity). Acetaminophen: 0.9-1.0 L/kg (distributes evenly in body fluids).
Hydrocodone: 3-4 L/kg (extensive tissue distribution). Acetaminophen: ~1 L/kg (uniformly distributed).
Propoxyphene: oral bioavailability ~40% due to first-pass metabolism. Acetaminophen: oral bioavailability 80-90%.
Oral: Hydrocodone ~70% (high first-pass metabolism); Acetaminophen ~85-90% (minimal first-pass).
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.
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 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 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 pediatric use due to risk of serious adverse effects; safety and efficacy not established.
Not recommended for pediatric patients; safety and efficacy not established for children under 18 years. For adolescents ≥18 years: adult dosing.
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 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.
Propoxyphene has been withdrawn from the US market due to risk of fatal overdose; Darvocet is no longer available in the US.
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.
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 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 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; known or suspected GI obstruction; hypersensitivity to hydrocodone or acetaminophen; concomitant use of 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 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.
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 (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.
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.
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.
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 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.
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 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 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.
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 DARVOCET vs ANEXSIA 7.5/325, 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 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 DARVOCET 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 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 7.5/325 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 DARVOCET 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. 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 7.5/325 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.