Description

Simple

A medication used to reduce fever and treat pain.

Clinical

An analgesic drug used alone or in combination with opioids for pain management, and as an antipyretic agent.

Overview

Acetaminophen (paracetamol), also commonly known as _Tylenol_, is the most commonly taken analgesic worldwide and is recommended as first-line therapy in pain conditions by the World Health Organization (WHO).[10] It is also used for its antipyretic effects, helping to reduce fever.[23] This drug was initially approved by the U.S. FDA in 1951 and is available in a variety of forms including syrup form, regular tablets, effervescent tablets, injection, suppository, and other forms.[15,16,23,Label]

Acetaminophen is often found combined with other drugs in more than 600 over the counter (OTC) allergy medications, cold medications, sleep medications, pain relievers, and other products.[19] Confusi... Read more

Pharmacology

Indication

In general, acetaminophen is used for the treatment of mild to moderate pain and reduction of fever.[23] It is available over the counter in various forms, the most common being oral forms.

Acetamino... Read more

Pharmacodynamic

Animal and clinical studies have determined that acetaminophen has both antipyretic and analgesic effects. This drug has been shown to lack anti-inflammatory effects. As opposed to the _salicylate_ drug class, acetaminophen does not disrupt tubular secretion of uric acid and does not affect acid-bas... Read more

Mechanism of action

According to its FDA labeling, acetaminophen's exact mechanism of action has not been fully established[Label] - despite this, it is often categorized alongside NSAIDs (nonsteroidal anti-inflammatory drugs) due to its ability to inhibit the cyclooxygenase (COX) pathways.[ Read more

Absorption

Acetaminophen has 88% oral bioavailability and reaches its highest plasma concentration 90 minutes after ingestion.[ Read more

Protein binding

The binding of acetaminophen to plasma proteins is low (ranging from 10% to 25%), when given at therapeutic doses.[Label]

Volume of distribution

Volume of distribution is about 0.9L/kg. 10 to 20% of the drug is bound to red blood cells.[11 Read more

Clearance

Adults: 0.27 L/h/kg following a 15 mg/kg intravenous (IV) dose.[Label]Children: 0.34 L/h/kg following a 15 mg/kg intravenous (IV dose).[Label]

Half life

The half-life for adults is 2.5 h after an intravenous dose of 15 mg/kg.[Label] After an overdose, the half-life can range from 4 to 8 hours depending on the severity of injury to the liver, as it heavily metabolizes acetaminophen.[ Read more

Route of elimination

Acetaminophen metabolites are mainly excreted in the urine. Less than 5% is excreted in the urine as free (unconjugated) acetaminophen and at least 90% of the administered dose is excreted within 24 hours.[... Read more

Toxicity

LD50 = 338 mg/kg (oral, mouse); LD50 = 1944 mg/kg (oral, rat)[24]

**Overdose and liver toxicity**

Acetaminophen overdose may be manifested by renal tubular necrosis, hypoglycemic coma, and thrombo... Read more

Adverse Effects

Effect Regions Age Groups Incidences Evidence Type
Nausea US
  • adult
  • Kind: experimental
    • Percent: 34%
  • Kind: placebo
    • Percent: 31%
  • Clinical Trial
    Vomiting US
    • adult
  • Kind: experimental
    • Percent: 15%
  • Kind: placebo
    • Percent: 11%
  • Clinical Trial
    Pyrexia US
    • adult
  • Kind: experimental
    • Percent: 5%
  • Kind: placebo
    • Percent: 14%
  • Clinical Trial
    Headache US
    • adult
  • Kind: experimental
    • Percent: 10%
  • Kind: placebo
    • Percent: 9%
  • Clinical Trial
    Insomnia US
    • adult
  • Kind: experimental
    • Percent: 7%
  • Kind: placebo
    • Percent: 5%
  • Clinical Trial
    Atelectasis US
    • pediatric
  • Kind: experimental
    • Percent: ≥ 5
  • Agitation US
    • pediatric
  • Kind: experimental
    • Percent: ≥ 5
  • Nausea US
    • pediatric
  • Kind: experimental
    • Percent: ≥ 5
  • Vomiting US
    • pediatric
  • Kind: experimental
    • Percent: ≥ 5
  • Nausea US
    • pediatric
  • Kind: experimental
    • Percent: ≥ 5
  • Constipation US
    • pediatric
  • Kind: experimental
    • Percent: ≥ 5
  • Pruritis US
    • pediatric
  • Kind: experimental
    • Percent: ≥ 5
  • Nausea US
    • pediatric
  • Kind: experimental
    • Percent: >5%
  • Clinical Trial
    Constipation US
    • pediatric
  • Kind: experimental
    • Percent: >5%
  • Clinical Trial
    Pruritus US
    • pediatric
  • Kind: experimental
    • Percent: >5%
  • Clinical Trial
    Vomiting US
    • pediatric
  • Kind: experimental
    • Percent: >5%
  • Clinical Trial
    Hypotension US
    • pediatric
  • Kind: experimental
    • Percent: >1
  • Hypertension(HTN) US
    • pediatric
  • Kind: experimental
    • Percent: >1
  • Rash US
    • pediatric
  • Kind: experimental
    • Percent: >1
  • Periorbital edema US
    • pediatric
  • Kind: experimental
    • Percent: >1
  • Wheezing US
    • pediatric
  • Kind: experimental
    • Percent: >1
  • Stridor US
    • pediatric
  • Kind: experimental
    • Percent: >1
  • Pleural Effusion US
    • pediatric
  • Kind: experimental
    • Percent: >1
  • Hypoxia US
    • pediatric
  • Kind: experimental
    • Percent: >1
  • Edema, Pulmonary US
    • pediatric
  • Kind: experimental
    • Percent: >1
  • Oliguria US
    • pediatric
  • Kind: experimental
    • Percent: >1
  • Insomnia US
    • pediatric
  • Kind: experimental
    • Percent: >1
  • Headache US
    • pediatric
  • Kind: experimental
    • Percent: >1
  • Pain in extremity US
    • pediatric
  • Kind: experimental
    • Percent: >1
  • Muscle Spasm US
    • pediatric
  • Kind: experimental
    • Percent: >1
  • Hypervolemia US
    • pediatric
  • Kind: experimental
    • Percent: >1
  • Hypophosphatemia US
    • pediatric
  • Kind: experimental
    • Percent: >1
  • Hypomagnesemia US
    • pediatric
  • Kind: experimental
    • Percent: >1
  • Hypokalemia US
    • pediatric
  • Kind: experimental
    • Percent: >1
  • Albumin decreased US
    • pediatric
  • Kind: experimental
    • Percent: >1
  • Hepatic enzyme increase US
    • pediatric
  • Kind: experimental
    • Percent: >1
  • Pyrexia US
    • pediatric
  • Kind: experimental
    • Percent: >1
  • Edema peripheral US
    • pediatric
  • Kind: experimental
    • Percent: >1
  • Diarrhea US
    • pediatric
  • Kind: experimental
    • Percent: >1
  • Tachycardia US
    • pediatric
  • Kind: experimental
    • Percent: >1
  • Hypokalemia US
    • adult
  • Kind: experimental
    • Value: >0.05%
  • Kind: experimental
    • Percent: 1%
    • Value: >0.05%
  • Clinical Trial
    Muscle Spasms US
    • adult
  • Kind: experimental
    • Value: >0.05%
  • Kind: experimental
    • Percent: 1%
    • Value: >0.05%
  • Clinical Trial
    Aspartate aminotransferase increased US
    • adult
  • Kind: experimental
    • Value: >0.05%
  • Kind: experimental
    • Percent: 1%
    • Value: >0.05%
  • Clinical Trial
    Breath sounds abnormal US
    • adult
  • Kind: experimental
    • Percent: 1%
    • Value: >0.05%
  • Kind: experimental
    • Value: >0.05%
  • Clinical Trial
    Infusion site pain US
    • adult
  • Kind: experimental
    • Value: >0.05%
  • Kind: experimental
    • Percent: 1%
    • Value: >0.05%
  • Clinical Trial
    Edema peripheral US
    • adult
  • Kind: experimental
    • Percent: 1%
    • Value: >0.05%
  • Kind: experimental
    • Value: >0.05%
  • Clinical Trial
    Anemia US
    • adult
  • Kind: experimental
    • Value: >0.05%
  • Kind: experimental
    • Percent: 1%
    • Value: >0.05%
  • Clinical Trial
    Fatigue US
    • adult
  • Kind: experimental
    • Percent: 1%
    • Value: >0.05%
  • Kind: experimental
    • Value: >0.05%
  • Clinical Trial
    Anxiety US
    • adult
  • Kind: experimental
    • Value: >0.05%
  • Kind: experimental
    • Percent: 1%
    • Value: >0.05%
  • Clinical Trial
    Trismus US
    • adult
  • Kind: experimental
    • Percent: 1%
    • Value: >0.05%
  • Kind: experimental
    • Value: >0.05%
  • Clinical Trial

    Contraindications

    • Hypersensitivity:
      • true
    • Regions: US
    • Regions: US
    • Patient Conditions:
        • Name: Severe, active Liver Disease
        • Drugbank Id: DBCOND0112340
        • Modification Of:
          • Condition Status: active
          • Base:
            • Name: Liver Disease
            • Drugbank Id: DBCOND0028338
          • Severity:
            • Includes:
              • severe
    • Regions: US
    • Patient Conditions:
        • Name: Severe Hepatic Impairment
        • Drugbank Id: DBCOND0070791
        • Modification Of:
          • Base:
            • Name: Heptic Impairment
            • Drugbank Id: DBCOND0072269
          • Severity:
            • Includes:
              • severe

    Food Interactions

    Avoid alcohol. Alcohol may increase the risk of hepatotoxicity.

    Take with or without food. The absorption is unaffected by food.