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Generic Name: acetylcysteine
Brand Names: N-acetylcysteine, Mucomyst (discontinued brand)
Drug Class: Pulmonary, Other; Mucolytic Agent
What is acetylcysteine, and what is it used for?
Acetylcysteine, also known as N-acetylcysteine, is a mucolytic agent used in the treatment and diagnosis of pulmonary diseases. Acetylcysteine breaks up abnormal, thick and sticky mucus in the respiratory tract, reducing its viscosity and making it easier to cough up and clear from the lungs. Acetylcysteine also has anti-inflammatory and antioxidant properties.
Acetylcysteine lowers mucus viscosity by splitting the disulfide bonds of mucoproteins, which are vital for their structure and stability. Acetylcysteine is an antioxidant that protects the lungs by scavenging free radicals generated by inflammatory cells. Acetylcysteine also provides cysteine, an essential component of glutathione, the natural antioxidant in the body.
Acetylcysteine is approved as an adjuvant therapy to facilitate mucolysis in adult and pediatric patients with the following conditions of the respiratory tract:
- Chronic bronchopulmonary diseases including:
- Chronic emphysema
- Emphysema with bronchitis
- Chronic asthmatic bronchitis
- Tuberculosis
- Bronchiectasis
- Primary amyloidosis of the lung
- Acute bronchopulmonary diseases including:
- Pneumonia
- Bronchitis
- Tracheobronchitis
- Pulmonary complications of cystic fibrosis
- Tracheostomy care
- Pulmonary complications with surgery
- Use during anesthesia
- Post-traumatic chest conditions
- Atelectasis due to mucus obstruction
- Diagnostic bronchial studies including:
- Bronchography
- Bronchospirometry
- Bronchial wedge catheterization
Off-label uses:
- Keratoconjunctivitis sicca (dry eyes), administered as eye drops in adults and pediatric patients
- Prevention of contrast agent-associated nephrotoxicity, administered orally in adults
Orphan designation:
- Prevention of ototoxicity (toxicity to ears that can affect hearing and balance) caused by platinum-based chemotherapy to treat pediatric cancers
Acetylcysteine is also used as an antidote to reduce the extent of liver injury after acetaminophen overdose.
Warnings
- Do not use acetylcysteine in patients with known hypersensitivity.
- Do not use acetylcysteine in patients with acute asthma.
- After administration of acetylcysteine, an increased volume of liquified bronchial secretions may occur. When cough is inadequate, an open airway must be maintained open by mechanical suction, if necessary.
- When there is a mechanical block due to foreign body or local accumulation, the airway should be cleared by endotracheal aspiration, with or without bronchoscopy.
- Use acetylcysteine with caution in patients with asthma or history of bronchospasm. Bronchospasm may be promptly relieved by the use of a bronchodilator given by nebulization. If bronchospasm progresses, discontinue acetylcysteine immediately.
What are the side effects of acetylcysteine?
Common side effects of acetylcysteine include:
- Bronchospasm
- Disagreeable odor
- Drowsiness
- Fever
- Coughing up blood (hemoptysis)
- Increased volume of bronchial secretions
- Irritation of tracheal or bronchial tract
- Nausea
- Runny or stuffy nose
- Swelling and sores inside the mouth (stomatitis)
- Vomiting
- Clamminess
- Wheezing
- Shortness of breath
Serious side effects of acetylcysteine include:
- Chest tightness
- Bronchoconstriction
- Bleeding
This is not a complete list of all side effects or adverse reactions that may occur from the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may also report side effects or health problems to the FDA at 1-800-FDA-1088.
What are the dosages of acetylcysteine?
Nebulizer solution
- 10%
- 20%
Adult
Pulmonary Disease
- Facilitation of expectoration via mucolysis
- Solution (10 and 20%) may be used undiluted; 3-5 mL of 20% solution or 6-10 mL of 10% solution; administer 1 to 10 mL of 20% solution every 6-8 hours or 2 to 20 mL of 10% every 2 to 6 hours
Diagnostic Bronchography
- 1-2 mL of 20% solution or 2-4 mL of 10% solution administered 2-3 times by nebulization or by intratracheal instillation before the procedure
Acetaminophen Overdose
- See separate drug monograph, acetylcysteine (antidote)
Contrast Agent-Associated Nephrotoxicity (Off-label)
Prevention
- 600 mg orally every 12 hours for 2 days on the day before and day of contrast agent administration
Keratoconjunctivitis Sicca (Off-label)
- 1 drop of 10% solution in the eye(s) every 6-8 hours
Pediatric
Pulmonary Disease
- Facilitation of expectoration via mucolysis
- Children 1-11 months: 1-2 mL of 20% solution or 2-4 mL of 10% solution by nebulization every 6-8 hours as needed
- Children 1-11 years: 3-5 mL of 20% solution or 6-10 mL of 10% solution by nebulization every 6-8 hours as needed
- Children over 12 years: 5-10 mL of 10% or 20% solution by nebulization every 6-8 hours as needed
Acetaminophen Overdose
- See separate drug monograph, acetylcysteine (antidote)
Keratoconjunctivitis Sicca (Off-label)
- 1 drop of 10% solution in the eye(s) every 6-8 hours
Ototoxicity Caused by Platinum-Based Chemotherapy (Orphan)
Prevention of ototoxicity caused by platinum-based chemotherapeutic agents used to treat pediatric cancers
Dosing Considerations
- Direct instillation: 1-2 mL of 10% or 20% solution every hour as needed
- Routine nursing care of patients with tracheotomy: 1-2 mL of 10% or 20% solution every 1-4 hours by direct instillation into tracheotomy
- Instillation into a segment of the bronchopulmonary tree via small plastic catheter into the trachea (under local anesthesia and direct vision): 2-5 mL of 20% solution via a syringe connected to a catheter
- Instillation via percutaneous intratracheal catheter: 1-2 mL of 20% solution or 2-4 mL of 10% solution every 1-4 hours via a syringe connected to a catheter
Administration
- Administer aerosolized bronchodilator 10-15 minutes before administering acetylcysteine via nebulization
- Nebulizer solution may also be administered orally
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Overdose
In case of overdose, get medical help or contact a Poison Control Center immediately.
What drugs interact with acetylcysteine?
Inform your doctor of all medications you are currently taking, who can advise you on any possible drug interactions. Never begin taking, suddenly discontinue, or change the dosage of any medication without your doctor’s recommendation.
Acetylcysteine has no known severe interactions with other drugs.
Acetylcysteine has no known serious interactions with other drugs.
Moderate interactions of acetylcysteine include:
- activated charcoal
Mild interactions of acetylcysteine include:
- azithromycin
- bazedoxifene/conjugated estrogens
- chloramphenicol
- clarithromycin
- demeclocycline
- dichlorphenamide
- doxycycline
- erythromycin base
- erythromycin ethylsuccinate
- erythromycin lactobionate
- erythromycin stearate
- minocycline
- probenecid
- sodium picosulfate/magnesium oxide/anhydrous citric acid
- tetracycline
- vancomycin
The drug interactions listed above are not all of the possible interactions or adverse effects. For more information on drug interactions, visit the RxList Drug Interaction Checker.
It is important to always tell your doctor, pharmacist, or health care provider of all prescription and over-the-counter medications you use, as well as the dosage for each, and keep a list of the information. Check with your doctor or health care provider if you have any questions about the medication.
Pregnancy and breastfeeding
Acetylcysteine is a pregnancy category B drug.
- Acetylcysteine may be acceptable for use during pregnancy. Either animal studies show no risk but human studies are not available, or animal studies showed minor risks and human studies were done and showed no risk.
- It is not known if acetylcysteine is excreted in breast milk, use with caution.
What else should I know about acetylcysteine?
- Administer aerosolized bronchodilator 10-15 minutes before administering acetylcysteine via nebulization.
- There may be a slight temporary disagreeable odor after acetylcysteine administration.
- Face masks may produce a sticky film on the face after nebulization, which can be removed with water.
- Under certain conditions, an opened bottle may cause a slight purple color change as a consequence of chemical reaction; this has no effect on drug safety or efficacy.
