COMBOGESIC
Clinical safety rating: caution
Comprehensive clinical and safety monograph for COMBOGESIC (COMBOGESIC).
COMBOGESIC (acetaminophen and tramadol) combines a centrally acting analgesic (tramadol) that binds to mu-opioid receptors and inhibits serotonin and norepinephrine reuptake, with an antipyretic (acetaminophen) that inhibits cyclooxygenase (COX) in the CNS.
| Metabolism | Tramadol: primarily metabolized by CYP2D6 and CYP3A4; O-desmethyltramadol (active metabolite) via CYP2D6. Acetaminophen: primarily metabolized by glucuronidation and sulfation in the liver. |
| Excretion | Renal excretion of acetaminophen metabolites (glucuronide, sulfate, cysteine, and mercapturate conjugates); 85% total. Tramadol and metabolites: 90% renal, 10% fecal. |
| Half-life | Acetaminophen: 2-3 hours; Tramadol: 6.3 hours (slow CYP2D6 metabolizers may exceed 12 hours). Clinically, dosing interval adjusted for renal impairment. |
| Protein binding | Acetaminophen 10-25%; Tramadol 20% bound to albumin. |
| Volume of Distribution | Acetaminophen 0.9 L/kg; Tramadol 2.6 L/kg. Reflects extensive tissue distribution. |
| Bioavailability | Acetaminophen oral ~88%; Tramadol oral ~75% (due to first-pass metabolism). |
| Onset of Action | Oral: Acetaminophen 30-60 min, Tramadol 60 min. |
| Duration of Action | Acetaminophen 4-6 hours; Tramadol 4-6 hours (extended-release may provide 12-hour duration). |
One tablet (acetaminophen 500 mg / tramadol 37.5 mg) orally every 4 to 6 hours as needed for pain, not to exceed 8 tablets per day.
| Dosage form | TABLET |
| Renal impairment | For CrCl 30-59 mL/min: increase dosing interval to every 12 hours, maximum 4 tablets per day. For CrCl <30 mL/min: not recommended. Hemodialysis: administer dose after dialysis session, use with caution. |
| Liver impairment | Child-Pugh Class A: no adjustment. Child-Pugh Class B: reduce dose by 50% or extend interval; maximum 4 tablets per day. Child-Pugh Class C: contraindicated. |
| Pediatric use | Not recommended for pediatric use. Safety and efficacy not established in children. |
| Geriatric use | Initiate at lowest effective dose; consider extended dosing interval (every 8-12 hours) and monitor for adverse effects, particularly CNS and respiratory depression. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for COMBOGESIC (COMBOGESIC).
| Breastfeeding | Paracetamol: Excreted into breast milk in small amounts (M/P ratio ~0.23-0.91); considered compatible with breastfeeding. Tramadol: Excreted into breast milk (M/P ratio ~1.5-2.0); relative infant dose ~2.24% of maternal weight-adjusted dose. Monitor infant for sedation and respiratory depression; avoid in women with CYP2D6 ultra-rapid metabolizer status due to increased risk of high morphine levels in breast milk. |
| Teratogenic Risk | Combogesic contains paracetamol (acetaminophen) and tramadol. Paracetamol: No increased risk of major malformations; first trimester use is generally considered low risk. Second and third trimester: No known fetal toxicity at therapeutic doses. Tramadol: First trimester: Limited data, but no major teratogenicity observed in animal studies; human data insufficient to exclude risk. Second and third trimester: Not associated with structural anomalies; chronic use may lead to fetal dependence and neonatal withdrawal syndrome. At term: Risk of neonatal respiratory depression if used near delivery; tramadol may prolong labor and increase risk of postpartum hemorrhage. |
■ FDA Black Box Warning
Risk of addiction, abuse, and misuse; life-threatening respiratory depression; accidental ingestion; neonatal opioid withdrawal syndrome; risk of medication errors (combining different forms of acetaminophen leading to hepatotoxicity); serious, life-threatening, or fatal respiratory depression may occur when used with benzodiazepines or other CNS depressants.
| Serious Effects |
Hypersensitivity to tramadol, acetaminophen, or any component; significant respiratory depression; acute or severe bronchial asthma in an unmonitored setting or without resuscitative equipment; known or suspected gastrointestinal obstruction, including paralytic ileus; concomitant use of MAOIs or within 14 days of such therapy.
| Precautions | Addiction, abuse, and misuse; life-threatening respiratory depression; neonatal opioid withdrawal syndrome; risks from concomitant use with benzodiazepines or other CNS depressants; hepatotoxicity (associated with acetaminophen); seizures; serotonin syndrome; risk of overdose; interactions with MAOIs; CYP2D6 poor metabolizers may have reduced efficacy; risk of anaphylaxis and hypersensitivity. |
| Food/Dietary |
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| Fetal Monitoring | Regular assessment of liver function (paracetamol) and renal function. Monitor for signs of tramadol toxicity (respiratory depression, sedation, constipation). In pregnancy: Monitor fetal growth and amniotic fluid index if used chronically. At delivery: Monitor neonatal respiratory status and Apgar scores. Perform newborn assessment for withdrawal symptoms (irritability, tremors, feeding difficulties) if maternal use was prolonged. |
| Fertility Effects | Paracetamol: No established effect on fertility. Tramadol: May cause hyperprolactinemia, potentially impairing fertility via ovulatory dysfunction; animal studies show decreased implantation and altered sperm parameters at high doses. Caution in women attempting conception. |
| Avoid alcohol while taking Combogesic, as it increases the risk of liver damage with acetaminophen and gastrointestinal bleeding with ibuprofen. Taking with food may reduce gastric irritation. No specific food restrictions. |
| Clinical Pearls | Combogesic (paracetamol/acetaminophen + ibuprofen) is a fixed-dose combination used for acute pain. Note that the maximum daily dose of acetaminophen is 4000 mg (or lower in hepatic impairment) and ibuprofen 1200 mg (or lower in renal impairment). Avoid concomitant use of other NSAIDs or acetaminophen-containing products. Use with caution in patients with a history of peptic ulcer or bleeding disorders; ibuprofen may increase bleeding risk. |
| Patient Advice | Do not exceed the recommended dose as it may cause liver damage or kidney problems. · Avoid taking other products containing acetaminophen or NSAIDs (e.g., ibuprofen, naproxen) while using Combogesic. · Take with food or milk to reduce stomach upset. · Report any signs of stomach bleeding (e.g., black/tarry stools, vomiting blood), rash, or swelling. · Do not use for more than 10 days for pain unless directed by a doctor. |