Which medications in the drug class Antidotes, Other are used in the treatment of Acetaminophen Toxicity?

Updated: Jan 17, 2020
  • Author: Susan E Farrell, MD; Chief Editor: Michael A Miller, MD  more...
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Antidotes, Other

Gastrointestinal (GI) decontamination with oral AC is selectively used in the emergency treatment of poisoning caused by some drugs and chemicals. The network of pores present in AC adsorbs 100-1000 mg of drug per gram of charcoal. AC does not dissolve in water.

Consider GI decontamination with AC in any patient who presents within 1 hour after the ingestion. Maximum effect is achieved if AC is used within 1 hour post ingestion. AC may be helpful more than 4 hours post-ingestion, if co-ingestion with an agent that slows gut motility occurred or if a sustained-release preparation was ingested.

AC adsorbs acetaminophen, but its use has been controversial, because AC may absorb oral NAC. Although AC reduces the bioavailability of NAC, the small decrease in the NAC bioavailability is unlikely to reduce the effectiveness of oral NAC as an antidote.

NAC counteracts acetaminophen toxicity both directly and indirectly. NAC is converted to cysteine, which replenishes glutathione stores, thus providing a substrate for conjugation with the toxic metabolite of APAP, N -acetyl-p -benzoquinoneimine (NAPQI). NAC also directly detoxifies NAPQI to nontoxic metabolites.

Administer all doses of NAC as directed under the guidance of a regional poison control center. Shortened courses of NAC administration have been found to be effective in preventing liver toxicity in select patients with APAP overdose. [46, 47]

Activated charcoal (Actidose-Aqua, EZ-Char, Kerr Insta-Char)

Activated charcoal (AC) is the drug of choice for gastric decontamination and is used for emergency treatment in poisoning caused by drugs and chemicals. A network of pores absorbs 100-1000 mg of drug per gram of charcoal. AC prevents absorption by adsorbing the drug in the intestine.  AC does not dissolve in water and for maximum effect, administer this agent within 1 hour after ingestion of poison.

N-acetylcysteine (Acetadote)

N-acetylcysteine (NAC) is the drug of choice for the prevention and treatment of APAP-induced hepatotoxicity. This medication is approved by the US Food and Drug Administration (FDA) for both oral and intravenous (IV) administration. For the maximum hepatoprotective effects, administer NAC within 8-10 hours of an acute APAP ingestion.

Three treatment protocols are recognized: 72-hour oral, 21-hour IV, and 48-hour IV. The entire NAC protocol, either oral or IV regimen, should be completed even if serumacetaminophen concentrations decrease.

The oral form of NAC, Mucomyst, is available as a 20% solution (200 mg/mL). This should be diluted to 5% solution (50 mg/mL) with fruit juice or carbonated beverage. Aggressive antiemetic therapy is indicated in patients with nausea or vomiting due to acetaminophen-induced hepatic injury or foul sulfur odor of the solution. If the patient vomits within 60 min of administration, repeat the dose.

If failure to tolerate oral formulation persists, switch to the IV preparation (Acetadote). When administered intravenously, dilute NAC in 5% dextrose solution (D5W) and infuse per the recommended intravenous protocol for acute (within 8-10 h) or late-presenting or chronic acetaminophen ingestion.

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