acetylcysteine (Antidote)

Action and Spectrum

Actions and spectrum: 

acetylcysteine is an antidote that acts as a precursor of glutathione, a molecule that helps neutralize toxic substances in the body. It is primarily used to treat acetaminophen (paracetamol) overdose, a common cause of liver failure.

acetylcysteine can also treat other types of poisoning, such as carbon monoxide poisoning, and loosen thick mucus in conditions such as cystic fibrosis and chronic obstructive pulmonary disease (COPD). 

Drug Interaction

Adverse Reaction

Frequency not defined 

IV administration 

• Flushing 
• Urticaria 
• Nausea 
• Rhinorrhea 
• Anaphylactoid reaction 
• Edema 
• Pruritus 
• Pharyngitis

Oral administration 

• Vomiting 
• Chills 
• Nausea 
• Drowsiness 
• Fever 

Black Box Warning

Contraindication / Caution

Contraindication/Caution: 

Contraindication: 

acetylcysteine is contraindicated in individuals with a known hypersensitivity to acetylcysteine or any component of the formulation. It should also be used under caution in individuals with asthma, bronchospasm, or a history of peptic ulcer disease.  

Caution: 

• Bronchospasm: acetylcysteine should be used with caution in patients with a history of bronchospasm or asthma. It can cause bronchospasm or worsen pre-existing bronchospasm. 
• Bleeding disorders: acetylcysteine can increase the risk of bleeding, especially in patients with bleeding disorders. 
• Hypotension: acetylcysteine can cause hypotension or low blood pressure, especially if it is administered too rapidly. It should be administered with caution in patients who are hypotensive or who have a history of hypotension. 
• Seizure disorders: acetylcysteine can lower the seizure threshold and can cause seizures in susceptible patients. 
• Renal impairment: acetylcysteine should be used with caution in patients with renal impairment or pre-existing kidney disease, as it can cause further renal damage. 
• Hepatic impairment: acetylcysteine is primarily metabolized in the liver, and patients with hepatic impairment may require dose adjustments. 
• Allergic reactions: acetylcysteine can cause allergic reactions, including anaphylaxis, in some patients. 
• Pregnancy and lactation: acetylcysteine should only be used during pregnancy and lactation if the benefits outweigh the potential risks.

Comorbidities: 

acetylcysteine is generally well-tolerated, and there are no specific comorbidities that preclude its use as an antidote. However, it should be used under caution in patients with bronchospasm or asthma, as acetylcysteine may exacerbate these conditions.

Additionally, acetylcysteine may interact with other medications, so it is important to review a patient’s medication history prior to administration.

In patients with liver disease, acetylcysteine should be used with caution, as it may worsen hepatic encephalopathy. Finally, acetylcysteine should not be administered to patients with a known hypersensitivity to the drug. 

Pregnancy / Lactation

Pregnancy consideration: Pregnancy Category B 

Lactation: acetylcysteine is excreted in breast milk, so caution should be exercised if it is used during lactation.  

Pregnancy category: 

• Category A: Satisfactory and well-controlled studies show no risk to the fetus in the first or later trimester. 
• Category B: There is no evidence of risk to the fetus found in animal reproduction studies and there are not enough studies on pregnant women. 
• Category C: Adverse effects on the fetus found with evidence in animal reproduction studies and no adequate evidence for an effect in humans, care must be taken for potential risks in pregnant women. 
• Category D: There is adequate data available with sufficient evidence of human fetal risk from various platforms, but despite potential risks may be used only in emergency cases for potential benefits. 
• Category X: Drugs listed in this category outweigh risks over benefits These category drugs should be prohibited for pregnant women. 
• Category N: There is no data available for the drug under this category. 

Pharmacology

Pharmacology: 

acetylcysteine is a mucolytic agent that works by breaking down the disulfide bonds that are responsible for mucus viscosity. acetylcysteine is also a precursor to glutathione, a potent antioxidant that is essential for maintaining the cellular redox balance. In overdose situations, acetylcysteine is used as an antidote for acetaminophen poisoning.

acetylcysteine replenishes the depleted hepatic glutathione stores, thereby preventing the formation of toxic metabolites that cause liver injury. acetylcysteine is also used in the treatment of other pulmonary disorders, such as chronic obstructive pulmonary disease (COPD), cystic fibrosis, and bronchitis.  

Pharmacodynamics: 

acetylcysteine is a mucolytic agent that works by breaking disulfide bonds in mucus, resulting in decreased viscosity and improved clearance of respiratory secretions. As an antidote, it works by replenishing depleted glutathione stores in the liver and reducing the toxicity of reactive metabolites of acetaminophen. 

acetaminophen is a common analgesic and antipyretic medication, but when taken in large doses, it can cause hepatotoxicity due to the formation of toxic metabolites. acetylcysteine acts as an antidote to acetaminophen overdose by increasing the availability of glutathione, which binds to and neutralizes the toxic metabolites. It also provides an alternate pathway for the elimination of toxic metabolites and reduces the formation of additional toxic metabolites.  

Pharmacokinetics: 

Absorption 

acetylcysteine is rapidly absorbed after oral administration, with peak plasma concentrations occurring within 1-2 hours. The absolute bioavailability of oral acetylcysteine is low, at approximately 10%. After intravenous administration, acetylcysteine is rapidly and completely distributed throughout the body. 

Distribution 

acetylcysteine has a volume of distribution of approximately 0.47 L/kg, indicating that it is widely distributed throughout the body. It readily crosses the placenta and is distributed into breast milk. 

Metabolism 

acetylcysteine undergoes rapid and extensive metabolism in the liver, where it is deacetylated to cysteine and subsequently metabolized to other sulfur-containing compounds. 

Elimination and excretion 

acetylcysteine and its metabolites are excreted primarily in the urine, with approximately 13% of a dose being excreted unchanged within the first 24 hours after administration. The terminal elimination half-life of acetylcysteine is approximately 5.6 hours. 

Adminstartion

Administration: 

acetylcysteine is available in different forms for administration, including oral, inhalation, and intravenous routes. The route of administration and dosing may vary depending on the condition being treated. For example, in the treatment of acetaminophen overdose, oral or intravenous acetylcysteine is usually administered.

The oral dose of acetylcysteine for this purpose is typically given as a loading dose followed by maintenance doses over the next 20-72 hours. The intravenous formulation of acetylcysteine is administered as a single dose over 15 minutes, followed by a second dose over 4 hours and a third dose over 16 hours. 

In the treatment of respiratory conditions, acetylcysteine may be given by inhalation. The recommended dose for inhalation of acetylcysteine is usually 1-2 ampules per day, administered using a nebulizer or other inhalation device. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: acetylcysteine 

Pronounced: [ a-SEET-il-SIS-teen]  

Why do we use acetylcysteine (Antidote)? 

acetylcysteine is primarily used as an antidote for acetaminophen overdose, which is a common cause of acute liver failure. It is also used to thin mucus in the respiratory tract, making it easy to cough up, and it is used to treat conditions like chronic obstructive pulmonary disease, cystic fibrosis, and bronchitis.

acetylcysteine is also sometimes used as a treatment for certain types of kidney stones and to protect the kidney damage caused by certain diagnostic tests or medications. In addition, it may be used to reduce the risk of contrast-induced nephropathy, a type of kidney damage that can occur after certain medical procedures involving the use of contrast agents.