Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
DARVON COMPOUND vs ANEXSIA
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Darvon Compound is a combination of propoxyphene, aspirin, and caffeine. Propoxyphene is an opioid agonist that binds to mu-opioid receptors in the CNS, inhibiting ascending pain pathways and altering pain perception. Aspirin inhibits cyclooxygenase (COX) enzymes, reducing prostaglandin synthesis and providing anti-inflammatory and analgesic effects. Caffeine is a CNS stimulant that may enhance analgesia through adenosine receptor antagonism.
ANEXSIA is a combination of hydrocodone and acetaminophen. Hydrocodone is an opioid agonist that binds to mu-opioid receptors in the central nervous system, altering pain perception and emotional response to pain. Acetaminophen's analgesic mechanism is not fully understood but involves inhibition of COX enzymes in the CNS and modulation of descending serotonergic pathways.
Management of mild to moderate pain,As an antipyretic (aspirin component),Off-label: Not commonly used due to safety concerns
Relief of moderate to moderately severe pain
One capsule (propoxyphene HCl 65 mg, aspirin 389 mg, caffeine 32.4 mg) orally every 4 hours as needed for pain. Maximum 6 capsules per day.
50-100 mg orally every 4-6 hours as needed; maximum 400 mg/day.
Propoxyphene: 6-12 hours (terminal, prolonged in overdose due to enterohepatic recirculation). Acetaminophen: 2-3 hours (terminal). Clinical context: accumulation in elderly, hepatic impairment.
Terminal elimination half-life is 4-6 hours in adults with normal renal function; prolonged to 12-24 hours in severe renal impairment (Cr Cl <30 m L/min).
Propoxyphene: Hepatic via CYP3A4 to norpropoxyphene (active metabolite); Aspirin: Hydrolyzed by esterases to salicylate, further conjugated in the liver; Caffeine: Hepatic via CYP1A2 to paraxanthine, theobromine, and theophylline.
Hydrocodone is metabolized via CYP2D6 and CYP3A4 to hydromorphone and norhydrocodone. Acetaminophen is primarily metabolized via hepatic glucuronidation and sulfation; a minor pathway via CYP2E1 produces NAPQI, which is detoxified by glutathione.
Renal: ~70% as unchanged drug and glucuronide conjugates (propoxyphene and acetaminophen). Fecal: <10% as unchanged and metabolites. Biliary: minor route for propoxyphene conjugates.
Approximately 70% renal (unchanged drug and metabolites), 20% biliary/fecal, 10% other.
Propoxyphene: ~80% (albumin). Acetaminophen: 10-25% (albumin; lower at toxic concentrations).
Approximately 95% bound to plasma albumin and alpha-1-acid glycoprotein.
Propoxyphene: 0.9-1.2 L/kg (wide distribution, high tissue binding). Acetaminophen: 0.8-1.0 L/kg (uniform distribution).
0.2-0.4 L/kg, indicating limited extravascular distribution primarily confined to plasma and interstitial fluid.
Propoxyphene: 30-70% (first-pass metabolism, dose-dependent; higher with food). Acetaminophen: 60-90% (oral, variable first-pass; >95% for rectal? Not applicable here).
Oral: 80-90%; Intramuscular: 90-100%; Rectal: 70-80%.
Contraindicated in severe renal impairment (e GFR <30 m L/min). For moderate impairment (e GFR 30-59 m L/min): reduce dose to 1 capsule every 6 hours; maximum 4 capsules/day. Avoid in ESRD.
GFR 30-89 m L/min: no adjustment; GFR 15-29 m L/min: 50% dose reduction; GFR <15 m L/min: avoid use.
Contraindicated in Child-Pugh class C. For Child-Pugh class A or B: reduce dose by 50% (max 3 capsules/day) and monitor for sedation and respiratory depression.
Child-Pugh A: no adjustment; Child-Pugh B: 50% dose reduction; Child-Pugh C: avoid use.
Not recommended for pediatric patients due to risk of propoxyphene cardiotoxicity and aspirin-associated Reye's syndrome in viral illness.
1-2 mg/kg/dose orally every 6 hours; maximum 6 mg/kg/day.
Initiate with 1 capsule every 6 hours; maximum 4 capsules/day. Avoid in patients >80 years due to increased risk of CNS depression, falls, and bleeding from aspirin.
Initiate at 25 mg every 6 hours; increase cautiously; monitor renal function.
Propoxyphene has been withdrawn from the U. S. market due to risk of fatal overdose (QT prolongation and cardiac arrhythmias). Use is contraindicated in patients at risk for QT prolongation. Avoid concurrent use with CYP3A4 inhibitors.
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 from acetaminophen.
Risk of fatal overdose (QT prolongation, cardiac arrest); respiratory depression; drug dependence and abuse; caution in renal or hepatic impairment; avoid in patients with bleeding disorders (aspirin); Reye's syndrome risk in children with viral illness; caffeine may worsen anxiety or insomnia.
Risk of respiratory depression, especially in elderly or debilitated patients; adrenal insufficiency; severe hypotension; seizures; opioid-induced hyperalgesia; acetaminophen hepatotoxicity (avoid exceeding 4 g/day); serotonin syndrome if used with serotonergic agents.
Hypersensitivity to propoxyphene, aspirin, caffeine, or NSAIDs; patients with QT interval prolongation or on QT-prolonging drugs; concurrent use of CYP3A4 inhibitors (e.g., ketoconazole, ritonavir); children with viral illness (Reye's syndrome risk); severe renal or hepatic impairment; asthma or nasal polyps (aspirin sensitivity); active peptic ulcer disease or bleeding disorders.
Hypersensitivity to hydrocodone or acetaminophen; significant respiratory depression; acute or severe bronchial asthma in an unmonitored setting; known or suspected GI obstruction; severe hepatic impairment; concomitant use of MAOIs or within 14 days.
Avoid alcohol, as it increases propoxyphene CNS depression and hepatotoxicity. Limit caffeine-containing foods/beverages due to additive effects with caffeine component. Aspirin absorption is delayed by food; take on empty stomach for faster relief, but with food if GI upset occurs.
Avoid alcohol; may increase risk of hepatotoxicity and GI bleeding. Limit caffeine intake from coffee, tea, cola, or energy drinks due to added caffeine content. High-fat meals may delay absorption; take on empty stomach for faster onset if tolerated.
Darvon Compound contains propoxyphene and acetaminophen. Propoxyphene: FDA pregnancy category C; risk of respiratory depression in neonates if used near term; increased risk of premature labor and low birth weight with chronic use; possible congenital malformations (cleft palate, cardiac defects) in first trimester based on animal studies. Acetaminophen: generally considered low risk in pregnancy; no consistent evidence of teratogenicity. Avoid in third trimester due to risk of neonatal withdrawal syndrome.
First trimester: Data are limited; no increased risk of major malformations reported in small studies. Second and third trimesters: Associated with premature closure of the ductus arteriosus and oligohydramnios due to fetal renal effects; avoid use after 30 weeks gestation.
Propoxyphene excreted in breast milk in low concentrations (M/P ratio ~0.2); may cause sedation or respiratory depression in infants; avoid use in breastfeeding due to potential CNS effects. Acetaminophen M/P ratio ~0.9-1.0, considered compatible at recommended doses.
Excreted into breast milk in low concentrations (M/P ratio not established). Not recommended during breastfeeding due to potential for adverse effects in the infant, including renal impairment and gastrointestinal bleeding.
Due to increased plasma volume and hepatic metabolism during pregnancy, propoxyphene clearance may be increased, potentially requiring dose adjustments; however, due to risk of neonatal respiratory depression and withdrawal, avoid use or use lowest effective dose for shortest duration. Acetaminophen pharmacokinetics minimally altered; standard dosing applies.
Dose adjustment not generally required; however, due to increased renal clearance in pregnancy, shortened dosing intervals may be necessary for sustained efficacy. Use lowest effective dose for shortest duration.
Darvon Compound contains propoxyphene, aspirin, and caffeine. Due to propoxyphene's risk of QT prolongation and fatal arrhythmias, especially at supratherapeutic doses, it was withdrawn from the US market in 2010. Use is contraindicated in patients with prolonged QT interval, electrolyte disturbances, or on other QT-prolonging drugs. Aspirin component requires caution in bleeding disorders, peptic ulcer disease, and children with viral illness due to Reye's syndrome risk. Caffeine may exacerbate anxiety or insomnia.
ANEXSIA is a combination analgesic containing paracetamol, ibuprofen, and caffeine. It is contraindicated in patients with active peptic ulcer disease, severe hepatic impairment, or hypersensitivity to NSAIDs. Avoid concurrent use with other NSAIDs or paracetamol-containing products. Monitor renal function in elderly or dehydrated patients. Caffeine may exacerbate anxiety or insomnia.
Do not exceed recommended dose; propoxyphene overdose can cause life-threatening heart rhythm problems.,Avoid alcohol and other CNS depressants while taking this medication.,If you have a history of heart disease, low potassium/magnesium, or take other medications, inform your doctor.,Aspirin may increase bleeding risk; avoid if you have stomach ulcers or take blood thinners.,Discontinue and seek medical attention if you experience fainting, rapid heartbeat, or signs of allergic reaction.,Keep out of reach of children; accidental overdose can be fatal.
Do not exceed recommended dose; overdosage of paracetamol can cause liver damage.,Take with food or milk to reduce gastrointestinal upset.,Avoid alcohol while taking this medication to reduce risk of liver toxicity and GI bleeding.,Discontinue use and consult if signs of allergic reaction, GI bleeding, or liver problems occur.,Caffeine may cause nervousness, insomnia, or increased heart rate; limit caffeine-containing foods and beverages.
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 DARVON COMPOUND vs ANEXSIA, answered by our medical review team.
DARVON COMPOUND is a Opioid Analgesic Combination that works by Darvon Compound is a combination of propoxyphene, aspirin, and caffeine. Propoxyphene is an opioid agonist that binds to mu-opioid receptors in the CNS, inhibiting ascending pain pathways and altering pain perception. Aspirin inhibits cyclooxygenase (COX) enzymes, reducing prostaglandin synthesis and providing anti-inflammatory and analgesic effects. Caffeine is a CNS stimulant that may enhance analgesia through adenosine receptor antagonism.. ANEXSIA is a Opioid Analgesic Combination that works by ANEXSIA is a combination of hydrocodone and acetaminophen. Hydrocodone is an opioid agonist that binds to mu-opioid receptors in the central nervous system, altering pain perception and emotional response to pain. Acetaminophen's analgesic mechanism is not fully understood but involves inhibition of COX enzymes in the CNS and modulation of descending serotonergic pathways.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between DARVON COMPOUND and ANEXSIA 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 DARVON COMPOUND is: One capsule (propoxyphene HCl 65 mg, aspirin 389 mg, caffeine 32.4 mg) orally every 4 hours as needed for pain. Maximum 6 capsules per day.. The standard adult dose of ANEXSIA is: 50-100 mg orally every 4-6 hours as needed; maximum 400 mg/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 DARVON COMPOUND and ANEXSIA 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. DARVON COMPOUND is classified as Category C. Darvon Compound contains propoxyphene and acetaminophen. Propoxyphene: FDA pregnancy category C; risk of respiratory depression in neonates if used near term; increased risk of pre. ANEXSIA is classified as Category C. First trimester: Data are limited; no increased risk of major malformations reported in small studies. Second and third trimesters: Associated with premature closure of the ductus . Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.