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Acetaminophen
Aka: Acetaminophen, Tylenol, Paracetamol, N-acetyl-p-aminophenol
- See Also
- Acetaminophen Overdose
- Intravenous Acetaminophen
- Indications
- Mild to Moderate Pain
- Combined with other Analgesics for moderate to severe pain
- Fever
- Contraindications
- Severe hepatic insufficiency
- Severe progressive liver disease
- Acetaminophen Hypersensitivity
- Efficacy: Rheumatologic Conditions
- Scheduled dosing much more effective than prn
- Tylenol 1000 mg qid is as effective as Tylenol #3
- Dosing: Children
- Avoid overdosage of the Acetaminophen component at all cost (err on the side of underdosage)
- Acetaminophen
- Well hydrated child: 15 mg/kg every 6 hours
- Dehydration risk: 10 mg/kg every 6 hours
- Dosing by age (use only for an isolated single dose)
- Use measured weight based dosing for any subsequent doses!
- Age >2 months (5 kg): 80 mg per dose
- Age >4 months (6.5 kg): 100 mg per dose
- Age >6 months (8 kg): 120 mg per dose
- Age >12 months (10 kg): 160 mg per dose
- Age >2 years (13 kg): 200 mg per dose
- Age >3 years (15 kg): 240 mg per dose
- Age >5 years (19 kg): 280 mg per dose
- Maximum
- Do not exceed 75 mg/kg/day (up to 4 grams per day)
- Dosing: Adults (weight >50 kg)
- Regular Dose: 650 mg orally every 4 to 6 hours prn
- Higher Dose (Osteoarthritis)
- Regular Strength Tablet (325 mg)
- Take 975 mg (3 tablets) orally every 6 hours
- Extra-Strength Tablet (500 mg)
- Take 1000 mg (2 tablets) orally every 6 hours
- Maximum: 4 grams per day
- Limit to 2 grams per day maximum in advanced liver disease or severe Alcohol Use Disorder
- Do not exceed 12 regular strength tablets (325 mg)
- Do not exceed 8 extra-strength tablets (500 mg)
- Pharmacokinetics
- Similar potency and time-effect curve to Aspirin
- Duration: 4 hours
- Onset: 10 to 60 min (within 5-10 min for intravenous form)
- Preparations
- Chewable: 80 mg
- Elixir: 160 per 5 ml
- Dropper: 80 mg per 0.8 ml
- Suppository: 120 mg, 325 mg, 650 mg
- Tablet
- Regular strength: 325 mg
- Extra-Strength: 500 mg
- Intravenous (Ofirmev)
- Available in generic formulation expected in 2022
- Combination agents with Opioids
- Vicodin or Lortab (Acetaminophen with Hydrocodone)
- Percocet (Acetaminophen with Oxycodone)
- Combination agents - miscellaneous
- Excedrin Migraine (Acetaminophen with Aspirin and Caffeine)
- Sudafed PE (Acetaminophen with Diphenhydramine and Phenylephrine)
- Adverse Effects: Hepatotoxicity
- See Acetaminophen Toxicity
- Drug-Induced Skin Reaction (Stevens Johnson Syndrome, Toxic Epidermal Necrolysis)
- http://www.fda.gov/downloads/Drugs/DrugSafety/UCM363052.pdf
- Safety: Pregancy
- FDA Pregnancy Category B
- As with all Medications in Pregnancy, use the lowest effective dose in concert with non-pharmacologic measures
- Acetaminophen continues to be the preferred Analgesic in pregnancy without major safety concerns
- (2021) Presc Lett 28(11): 63-4
- May be associated with increased risk of ADHD in children with prolonged regular use (>6 weeks)
- However Acetaminophen association with ADHD is very weak, and without any evidence of causality (observational study)
- Cooper (2014) JAMA Pediatr 168(4):306-307 [PubMed]
- Untreated fever over 101 F is also associated with increased fetal risks in pregnancy (and NSAIDs present additional risks)
- Dreier (2014) Pediatrics 133(3): e674-88 [PubMed]
- Precautions
- Dehydration predisposes to overdosage
- Never exceed maximum daily dosage (hepatotoxicity)
- References
- LoVecchio (2021) Crit Dec Emerg Med 35(12): 32
- (2000) Med Lett Drugs Ther 42(1085):73-8 [PubMed]
- (1996) Med Lett Drugs Ther 38:5 [PubMed]
- Katzung (1989) Basic and Clinical Pharmacology