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Acetaminophen
From WikiSM
Other Names
- Tylenol
- Paracetamol
Introduction
- Type: Analgesic, Antipyretic
- Dosage Forms: IV; PO; PR
Adult Dosing
- PO
- Regular strength: 650mg q4-6 hours
- Extra strength: 1000mg q6 hours
- Extended-release: 1300mg q8 hours
- Rectal: 650mg q4-6 hours
- IV:
- <50 kg: 15mg/kg q6 hours or 12.5mg/kg q4 hours
- ≥50 kg: 650mg q4 hours or 1000mg q6 hours
- Maximum daily dose: 4g
Pediatric Dosing
- 15mg/kg/dose q6 hours
Special Populations
- Pregnancy Rating: B
- Lactation Risk Categories: safe
- Renal Dosing
- Adult: CrCl 10-50: give q6h, CrCl <10: give q8h
- Pediatric: CrCl 10-50: give q6h, CrCl <10: give q8h
- Hepatic Dosing
- Adult: not defined
- Pediatric: not defined
Evidence
General
- General
- When combined with 400 mg ibuprofen, 1000 mg ibuprofen was noninferior to opiates for acute extremity pain in the ED[1]
- Postoperative pain
- Cochrane review: single dose of paracetamol provides effective analgesia for about half of patients with acute postoperative pain, for a period of about four hours[2]
- Osteoarthritis
- Cochrane review: NSAIDS are superior to Acetaminophen for improving knee and hip pain in people with OA[3]
- Treatment size is modest, median trial duration only six weeks
Lower Extremity
- Hip Osteoarthritis
- Systematic review (2015): no or little efficacy with dubious clinical relevance for treatment of chronic pain due to hip OA[4]
- Knee Osteoarthritis
- Systematic review (2015): no or little efficacy with dubious clinical relevance for treatment of chronic pain due to knee OA[4]
Contraindications
- Allergies
- Chronic Liver Disease
Adverse Reactions
- Major
- Acetaminophen Toxicity
- Anemia
- Thrombocytopenia
- Minor
- Nausea
- Rash
- Headache
Pharmacology
- Half-life: 2-4 hour
- Metabolism: Liver
- Excretion: urine
- Mechanism of Action
- Poorly understood
- Antipyretic effect via direct action on the hypothalamic heat-regulating center
Drug Interactions
- Substances that induce the enzyme CYP2E1 may alter acetaminophen metabolism and increase the risk of hepatotoxicity
- Chronic oral acetaminophen use at a dose of 4,000 mg/day may increase the INR in patients stabilized on warfarin
Other Considerations
- When calculating maximum daily dose consider all sources of acetaminophen
See Also
References
- ↑ Chang AK, Bijur PE, Esses D, Barnaby DP, Baer J. Effect of a Single Dose of Oral Opioid and Nonopioid Analgesics on Acute Extremity Pain in the Emergency Department: A Randomized Clinical Trial. JAMA. 2017;318(17):1661‐1667.
- ↑ Toms, Laurence, et al. "Single dose oral paracetamol (acetaminophen) for postoperative pain in adults." Cochrane database of systematic reviews 4 (2008).
- ↑ Towheed, Tanveer, et al. "Acetaminophen for osteoarthritis." Cochrane Database of Systematic Reviews 1 (2006).
- ↑ 4.0 4.1 Ennis, Zandra Nymand, et al. "Acetaminophen for chronic pain: a systematic review on efficacy." Basic & clinical pharmacology & toxicology 118.3 (2016): 184-189.
