PROPOXYPHENE HYDROCHLORIDE W/ ASPIRIN AND CAFFEINE
Clinical safety rating: avoid
Anticoagulants like warfarin increase bleeding risk Concomitant use with other NSAIDs increases GI toxicity Risk of Reye's syndrome in children and teenagers with viral infections.
Propoxyphene is a centrally acting opioid analgesic that binds to mu-opioid receptors. Aspirin inhibits cyclooxygenase (COX) enzymes, reducing prostaglandin synthesis. Caffeine is a CNS stimulant that may enhance analgesia.
| Metabolism | Propoxyphene is metabolized via hepatic CYP3A4 to norpropoxyphene. Aspirin is metabolized by esterases. Caffeine is metabolized by CYP1A2. |
| Excretion | Renal elimination of propoxyphene and its metabolites (mainly norpropoxyphene) accounts for approximately 70-90% of the dose; fecal excretion is minimal (<10%). Aspirin is renally eliminated as salicylates (75-90% as conjugates, 10% free), while caffeine is primarily metabolized and its metabolites are excreted renally. |
| Half-life | Propoxyphene: 6-12 hours (up to 36 hours in overdose); norpropoxyphene: 30-36 hours. Aspirin: 2-3 hours for low doses, up to 15-30 hours in overdose. Caffeine: 3-6 hours; prolonged in liver disease. |
| Protein binding | Propoxyphene: 80% bound to albumin; aspirin: 80-90% bound to albumin (dose-dependent); caffeine: 25-36% bound to albumin. |
| Volume of Distribution | Propoxyphene: 12-26 L/kg (extensive tissue distribution); aspirin: 0.15-0.2 L/kg (small, reflects plasma binding); caffeine: 0.6-0.8 L/kg (distributes into total body water). |
| Bioavailability | Propoxyphene: Oral bioavailability 30-70% (first-pass effect); aspirin: 50-80% (hydrolyzed to salicylate); caffeine: 100% nearly complete oral absorption. |
| Onset of Action | Oral: Propoxyphene analgesia onset in 30-60 minutes; aspirin analgesia/antipyresis in 30-60 minutes; caffeine CNS stimulation in 15-45 minutes. |
| Duration of Action | Propoxyphene: 4-6 hours; aspirin: 4-6 hours; caffeine: 3-4 hours. Duration may be extended in elderly or hepatic/renal impairment. |
1-2 capsules orally every 4-6 hours as needed; maximum 6 capsules per day. Each capsule contains propoxyphene hydrochloride 65 mg, aspirin 325 mg, and caffeine 32.4 mg.
| Dosage form | CAPSULE |
| Renal impairment | Contraindicated in severe renal impairment (CrCl <30 mL/min). For moderate impairment (CrCl 30-60 mL/min), reduce dose by 50% and monitor for CNS toxicity. |
| Liver impairment | Contraindicated in severe hepatic impairment (Child-Pugh class C). For moderate impairment (Child-Pugh class B), reduce dose by 50%. Use with caution in mild impairment (Child-Pugh class A). |
| Pediatric use | Not recommended for use in children under 18 years due to risk of respiratory depression and aspirin-associated Reye's syndrome. |
| Geriatric use | Initial dose of 1 capsule every 6-8 hours; maximum 4 capsules per day. Avoid concurrent use with other CNS depressants. Monitor renal function and for signs of toxicity. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Anticoagulants like warfarin increase bleeding risk Concomitant use with other NSAIDs increases GI toxicity Risk of Reye's syndrome in children and teenagers with viral infections.
| FDA category | Positive |
| Breastfeeding | Propoxyphene and its metabolite norpropoxyphene are excreted into breast milk. Milk-to-plasma ratio is approximately 1.0 for propoxyphene and 0.4 for norpropoxyphene. Risk of infant sedation and withdrawal. Aspirin passes into milk; use while breastfeeding not recommended due to Reye's syndrome risk in infants. Caffeine is excreted in low amounts. Avoid use in nursing mothers. |
■ FDA Black Box Warning
None
| Common Effects | fever |
| Serious Effects |
["Hypersensitivity to any component.","Significant respiratory depression.","Acute or severe bronchial asthma.","Known or suspected gastrointestinal obstruction.","Concurrent use of MAOIs or within 14 days.","Children or teenagers with viral infections (Reye's syndrome risk with aspirin).","Severe hepatic impairment.","QT interval prolongation or concurrent QT-prolonging drugs."]
| Precautions | ["Risk of respiratory depression, abuse potential, and dependence with propoxyphene.","Propoxyphene may prolong the QT interval; avoid in patients with electrolyte abnormalities or QT prolongation.","Aspirin increases bleeding risk; use caution with anticoagulants or in patients with bleeding disorders.","Caffeine may cause insomnia, tremor, or tachycardia.","Avoid concurrent use with alcohol or other CNS depressants."] |
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| Teratogenic Risk |
| Propoxyphene is in FDA pregnancy category C. First trimester: Risk of congenital malformations not established; limited human data. Second trimester: No specific teratogenic effects reported; use with caution. Third trimester: Risk of neonatal respiratory depression, withdrawal syndrome (irritability, hypertonia, tremors), and prolonged bleeding due to aspirin component (inhibits platelet aggregation). Aspirin is associated with premature closure of ductus arteriosus and oligohydramnios, especially in third trimester. |
| Fetal Monitoring | Monitor maternal respiratory status, sedation, constipation. Fetal monitoring for heart rate variability (nonstress test) if used near term. Neonatal monitoring for respiratory depression, withdrawal symptoms (e.g., irritability, poor feeding), and bleeding (due to aspirin) if used in third trimester. Platelet function in newborn may be impaired. |
| Fertility Effects | Propoxyphene: Limited data; no known direct effect on fertility. Aspirin: May inhibit prostaglandin synthesis, potentially affecting ovulation and implantation; high doses may impair fertility. Caffeine: Some studies suggest high intake may delay conception. Overall, combination not recommended for fertility patients. |