Please check your internet connection and try again.
# **Acetaminophen**
## Overview
Acetaminophen (APAP) is an analgesic and antipyretic agent. Its exact mechanism of action is not fully understood but is believed to involve inhibition of prostaglandin synthesis in the central nervous system.
## Primary Indications
* Mild to moderate pain
* Fever
## Adult Dosing
* **Pain and Fever:** 325 mg to 1000 mg orally every 4 to 6 hours as needed.
* **Maximum Daily Dose:** 4000 mg per 24 hours. For patients with chronic alcohol use or severe liver disease, the maximum daily dose should not exceed 3000 mg per 24 hours.
## Pediatric Dosing
Dosing is based on weight. Dosing intervals are typically every 4 to 6 hours. **Always confirm weight-based dosing with a reliable pediatric reference or local protocol.**
* **Analgesia and Antipyresis:** 10 mg/kg/dose orally or rectally every 4 to 6 hours.
* **Maximum Daily Dose:** Generally not to exceed 75 mg/kg/day, and should not exceed the adult maximum of 4000 mg/day.
## Dose Adjustments
* **Hepatic Impairment:** Use with caution. Reduce maximum daily dose to 3000 mg/day in patients with severe hepatic impairment or chronic alcohol use.
* **Renal Impairment:** No dose adjustment is typically required for standard doses. However, caution may be advised in severe renal impairment due to potential accumulation of metabolites.
## Contraindications
* Known hypersensitivity to acetaminophen.
* Severe hepatic impairment or severe active liver disease.
## Adverse Effects
* **Common:** Nausea, vomiting.
* **Serious:** Hepatotoxicity (especially with overdose or chronic overuse), skin reactions (e.g., Stevens-Johnson syndrome, toxic epidermal necrolysis).
## Key Drug Interactions
* **Warfarin:** Chronic, excessive alcohol intake combined with acetaminophen may increase the anticoagulant effect of warfarin.
* **Isoniazid, Phenytoin, Carbamazepine, Rifampin, Barbiturates, and certain Anticonvulsants:** These agents can increase the risk of hepatotoxicity by inducing liver enzymes.
* **Probenecid:** May decrease the clearance of acetaminophen, potentially increasing its levels.
## Monitoring
* Liver function tests (LFTs) may be considered in patients with risk factors for liver disease or those taking high doses chronically.
* Monitor for signs and symptoms of hepatotoxicity (e.g., jaundice, abdominal pain, dark urine).
## Clinical Pearls
* Acetaminophen is found in many over-the-counter (OTC) and prescription combination products. Patients should be counseled to avoid taking multiple acetaminophen-containing products simultaneously to prevent accidental overdose.
* The risk of hepatotoxicity is significantly increased with overdose and in patients who consume alcohol regularly.
* Intravenous acetaminophen is also available and has different dosing and administration considerations.
***
**Disclaimer:** This information is intended for educational purposes and is not a substitute for professional medical advice. Always verify current prescribing information and consult with a qualified healthcare provider before making any treatment decisions.
