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. |
| Molecular Weight | 373.92 |
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 | Avoid; propoxyphene is FDA pregnancy category C; associated with fetal abnormalities in animal studies; aspirin may cause maternal and fetal bleeding; caffeine may be associated with low birth weight. |
| 2nd trimester | Avoid; propoxyphene carries risk of neonatal respiratory depression; aspirin linked to premature closure of ductus arteriosus; caffeine should be limited. |
| 3rd trimester | Avoid; propoxyphene may cause neonatal withdrawal and respiratory depression; aspirin use in third trimester increases risk of premature ductus closure and hemorrhage; caffeine may be harmful. |
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 |
| Placental transfer | Propoxyphene and its metabolite norpropoxyphene cross the placenta; aspirin readily crosses placenta; caffeine also crosses placenta. Evidence indicates significant transfer for all components. |
■ FDA Black Box Warning
None
| Common Effects | fever |
| Serious Effects |
Hypersensitivity to propoxyphene, aspirin, or caffeineSignificant respiratory depressionAcute or severe bronchial asthmaKnown or suspected gastrointestinal obstructionConcurrent use with alcohol or other CNS depressantsSevere bleeding disorders (e.g., hemophilia) due to aspirin componentChildren and adolescents with viral infections due to aspirin-associated Reye's syndrome risk
| 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. |
| Food/Dietary |
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| Breastfeeding | Propoxyphene is excreted into breast milk in small amounts; however, the combination with aspirin and caffeine may cause irritability, poor feeding, or sedation in infants. Aspirin is associated with Reye's syndrome risk in infants. Caffeine may cause irritability and poor sleep. Not recommended during breastfeeding. |
| Lactation Rating | L4 - Possibly Hazardous |
| 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. |
| Avoid grapefruit and grapefruit juice as they may increase propoxyphene levels. Caffeine content may cause insomnia or jitteriness; limit additional caffeine intake. Aspirin component may irritate stomach; take with food or milk to reduce GI upset. |
| Clinical Pearls | Propoxyphene is a weak opioid with potential for cardiac toxicity (QT prolongation, Torsades de Pointes) at high doses. Avoid in elderly and patients with renal impairment due to accumulation of cardiotoxic metabolite norpropoxyphene. Do not exceed 600 mg/day of propoxyphene hydrochloride. Combination with aspirin and caffeine does not enhance analgesia beyond propoxyphene alone. Risk of respiratory depression increased with alcohol or other CNS depressants. Monitor for signs of abuse. |
| Patient Advice | Take exactly as prescribed. Do not increase dose or frequency. · May cause drowsiness or dizziness. Avoid driving or operating heavy machinery. · Avoid alcohol while taking this medication. · Do not take with other medications containing aspirin or NSAIDs without consulting doctor. · Report symptoms of irregular heartbeat, fainting, or seizures immediately. · Do not stop abruptly; may cause withdrawal symptoms. · Keep out of reach of children. Overdose can be fatal. · Store at room temperature away from moisture. |