Acetylcysteine

Class and Category

Pharmacologic class: L-cysteine derivative

Therapeutic class: Antidote (for acetaminophen overdose), mucolytic

Indications and Dosages

👉   To liquefy abnormal, thickened, or viscid mucus secretions in chronic pulmonary disorders (including bronchiectasis, bronchitis, cystic fibrosis, and emphysema) and in pneumonia, pulmonary complications of cardiovascular or thoracic surgery, and tracheostomy care

SOLUTION BY DIRECT INSTILLATION INTO TRACHEOSTOMY (ACETYLCYSTEINE)

Adults and children. 1 to 2 ml of 10% or 20% solution instilled every 1 to 4 hr, as needed.

SOLUTION BY INHALATION (ACETYLCYSTEINE)

Adults and children. 1 to 10 ml of 20% solution or 2 to 20 ml of 10% solution nebulized through face mask, mouthpiece, or tracheostomy every 2 to 6 hr.

Usual: 3 to 5 ml of 20% solution or 6 to 10 ml of 10% solution three or four times daily.

👉   To treat acetaminophen overdose

EFFERVESCENT TABLETS, SOLUTION P.O. (ACETYLCYSTEINE)

Adults and children. Loading dose: 140 mg/kg. Maintenance: 70 mg/kg 4 hr after loading dose and then every 4 hr to a total of 17 doses.

I.V. INFUSION (ACETADOTE)

Adults and children weighing 41 kg (90.2 lb) or more. 150 mg/kg in 200 ml of diluent infused over 60 min, followed by 50 mg/kg in 500 ml of diluent infused over 4 hr, followed by 100 mg/kg in 1,000 ml of diluent infused over 16 hr.

Adults and children weighing 20 kg (44 lb) to 41 kg (90.2 lb) 150 mg/kg in 100 ml of diluent infused over 60 min, followed by 50 mg/kg in 250 ml of diluent infused over 4 hr, followed by 100 mg/kg in 500 ml of diluent infused over 16 hr.

Children weighing 5 kg (11 lb) to 20 kg (44 lb). 150 mg/kg in 3 ml/kg of diluent infused over 60 min, followed by 50 mg/kg in 7 ml/kg of diluent infused over 4 hr, followed by 100 mg/kg in 14 ml/kg of diluent infused over 16 hr.

Mechanism of Action

Decreases viscosity of pulmonary secretions by breaking disulfide links that bind glycoproteins in mucus. Reduces liver damage from acetaminophen overdose. Usually, acetaminophen’s toxic metabolites bind with glutathione in the liver, which detoxifies them. When acetaminophen overdose depletes glutathione stores, toxic metabolites bind with protein in liver cells, killing them.

Acetylcysteine maintains or restores levels of glutathione or acts as its substitute, which reduces liver damage from acetaminophen overdose.

Incompatibilities

Don’t give acetylcysteine with nebulization equipment if drug can contact copper, iron, or rubber. Don’t give drug with amphotericin B, ampicillin sodium, chlortetracycline, chymotrypsin, erythromycin, hydrogen peroxide, iodized oil, oxytetracycline, tetracycline, or trypsin.

Contraindications

Hypersensitivity to acetylcysteine or its components, no contraindications when used as antidote

Interactions

DRUGS

Activated Charcoal: Possibly adsorption and decreased effectiveness of oral acetylcysteine

Nitroglycerin: Increased effects of nitroglycerin and possibly significant headache and hypotension

Adverse Reactions

CNS: Chills, dizziness, drowsiness, fever, headache

CV: Edema, hypertension, hypotension, tachycardia

EENT: Rhinorrhea, stomatitis, stridor, tooth damage

GI: Anorexia, constipation, hepatotoxicity, nausea, vomiting

RESP: Bronchospasm, chest tightness, cough, hemoptysis, respiratory distress, shortness of breath, wheezing

SKIN: Clammy skin, erythema, facial flushing, pruritus, rash, urticaria

Other: Anaphylaxis, angioedema

Childbearing Considerations

PREGNANCY

It is not known if drug can cause fetal harm.

Use with caution only if benefit to mother outweighs potential risk to fetus.

LACTATION

It is not known if drug is present in breast milk.

Patient should check with prescriber before breastfeeding. Breastfeeding women may consider pumping and discarding their milk for 30 hours after drug administration.

Nursing Considerations

• Know that acetylcysteine should be used cautiously in patients with asthma or a history of bronchospasm because drug may adversely affect respiratory function.

WARNING Treating acetaminophen overdose with intravenous therapy may require adjusting total administered volume, as ordered, for patients weighing less than 40 kg (88 lb) and for those who need fluid restriction, to avoid fluid overload and possibly fatal hyponatremia or seizures.

• Be aware that it may be necessary to dilute 20% inhalation or instillation solution with normal saline solution or sterile water when acetylcysteine is used to liquefy secretions. The 10% solution may be used undiluted.
• Follow guidelines for product prescribed when treating acetaminophen overdose. For example, dissolve appropriate number of 2.5 g and/or 500 mg effervescent tablets in water (for patients weighing 19 kg or less, dissolve in 100 ml of water; for patients weighing 20 to 60 kg, dissolve in 150 ml of water; and, for patients weighing 60 kg or more, dissolve in 300 ml of water). Once tablets are dissolved, administer oral solution immediately. For oral solution form (acetylcysteine), dilute 20% oral solution with cola or other soft drink to a concentration of 5%, and use within 1 hour.
• Dilute parenteral solution (Acetadote) with D5W or half-normal saline (0.45% sodium chloride) solution for injection following manufacturer guidelines because dilution is based on dosage.
• Acetadote may turn from colorless to slight pink or purple once the stopper is punctured, but color change has no effect on product quality.
• Keep in mind that acetylcysteine is most effective if given within 24 hours of acetaminophen ingestion. 
• Repeat dose as prescribed, if patient vomits loading dose or any maintenance dose within 1 hour of administration.
• Keep in mind that suicidal patient may not provide reliable information about vomiting. Watch such a patient to ensure that he ingests all of prescribed dosage.
• Watch for signs of hepatotoxicity (altered coagulation, easy bruising, and prolonged bleeding time), during treatment for acetaminophen overdose.
• Be aware that acetylcysteine may have a disagreeable odor, which disappears as treatment progresses.
• When drug is given intravenously, acute flushing and erythema of the skin may occur within 30 to 60 minutes of administration and often resolves spontaneously even with continued infusion of drug. However, monitor patient closely for acute hypersensitivity reactions regardless of form of drug administered, such as hypotension, rash, shortness of breath, and wheezing. If present, immediately stop administration of drug, notify prescriber, and provide supportive care according to protocol.
• Have patient wash his face and rinse his mouth at the end of each nebulization treatment because nebulization causes sticky residue on face and in mouth.
• Be aware that an open vial of solution may turn light purple but that this doesn’t alter its effectiveness.
• Refrigerate opened vials and discard after 96 hours.
• Assess type, frequency, and characteristics of patient’s cough. Particularly note sputum. If cough doesn’t clear secretions, prepare to perform mechanical suctioning.
• Monitor patient for tachycardia.

PATIENT TEACHING

• Tell patient receiving acetylcysteine intravenously that facial redness or flushing may occur but usually resolves on its own.
• Instruct patient to notify prescriber immediately about nausea, rash, or vomiting, as well as feeling dizzy or lightheaded, shortness of breath, or wheezing.
• Warn patient about acetylcysteine’s unpleasant smell; reassure him that it subsides as treatment progresses.
• Urge patient prescribed drug to loosen mucus, to consume 2 to 3 L of fluid daily unless contraindicated by another condition, to decrease mucus viscosity.
• Instruct female patient who is breastfeeding to consider pumping and discarding her milk for 30 hours after acetylcysteine administration.