Analgesic

Acetaminophen

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Acetaminophen, Tylenol, Paracetamol, N-acetyl-p-aminophenol

  • Indications
  1. Pain
  2. Fever (>102 F or Fever at bedtime)
  1. Scheduled dosing much more effective than prn
  2. Tylenol 1000 mg qid is as effective as Tylenol #3
  • Dosing
  • Children
  1. Avoid overdosage of the Acetaminophen component at all cost (err on the side of underdosage)
  2. Acetaminophen
    1. Well hydrated child: 15 mg/kg every 4 to 6 hours
    2. Dehydration risk: 10 mg/kg every 4 to 6 hours
    3. Dosing by age
      1. Age >2 months (5 kg): 80 mg per dose
      2. Age >4 months (6.5 kg): 100 mg per dose
      3. Age >6 months (8 kg): 120 mg per dose
      4. Age >12 months (10 kg): 160 mg per dose
      5. Age >2 years (13 kg): 200 mg per dose
      6. Age >3 years (15 kg): 240 mg per dose
      7. Age >5 years (19 kg): 280 mg per dose
    4. Maximum
      1. Do not exceed 75 mg/kg/day (up to 4 grams per day)
  • Dosing
  • Adults
  1. Regular Dose: 650 mg orally every 4 to 6 hours prn
  2. Higher Dose (Osteoarthritis)
    1. Regular Strength Tablet (325 mg)
      1. Take 975 mg (3 tablets) PO every 6 hours
    2. Extra-Strength Tablet (500 mg)
      1. Take 1000 mg (2 tablets) PO every 6 hours
  3. Maximum: 4 grams per day
    1. Do not exceed 12 regular strength tablets (325 mg)
    2. Do not exceed 8 extra-strength tablets (500 mg)
  • Pharmacokinetics
  1. Similar potency and time-effect curve to Aspirin
  2. Duration: 4 hours
  • Preparations
  1. Chewable: 80 mg
  2. Elixir: 160 per 5 ml
  3. Dropper: 80 mg per 0.8 ml
  4. Suppository: 120 mg, 325 mg, 650 mg
  5. Tablet
    1. Regular strength: 325 mg
    2. Extra-Strength: 500 mg
  6. Combination agents with Opioids
    1. Vicodin or Lortab (Acetaminophen with Hydrocodone)
    2. Percocet (Acetaminophen with Oxycodone)
  7. Combination agents - miscellaneous
    1. Excedrin Migraine (Acetaminophen with Aspirin and Caffeine)
    2. Sudafed PE (Acetaminophen with Diphenhydramine and Phenylephrine)
  • Safety
  • Pregancy
  1. FDA Pregnancy Category B
  2. May be associated with increased risk of ADHD in children with prolonged regular use (>6 weeks)
    1. However Acetaminophen association with ADHD is very weak, and without any evidence of causality (observational study)
    2. Cooper (2014) JAMA Pediatr 168(4):306-307 [PubMed]
  3. Untreated fever over 101 F is also associated with increased fetal risks in pregnancy (and NSAIDs present additional risks)
    1. Dreier (2014) Pediatrics 133(3): e674-88 [PubMed]
  • Precautions
  1. Dehydration predisposes to overdosage
  2. Never exceed maximum daily dosage (hepatotoxicity)
  • References