Sterile
Not For Injection

Acetylcysteine is for inhalation (mucolytic agent) or oral administration (acetaminophen antidote), available as a sterile, unpreserved solution (NOT FOR INJECTION). The solutions contain 20% (200 mg/mL) or 10% (100 mg/mL) acetylcysteine, with disodium edetate in water for injection. Sodium hydroxide and/or hydrochloric acid is added to adjust pH (range 6.0 - 7.5). Acetylcysteine is the N-acetyl derivative of the naturally-occurring amino acid, L-cysteine. The compound is a white crystalline powder with the molecular formula C5H9NO3S, a molecular weight of 163.2, and chemical name of N-acetyl-L-cysteine. Acetylcysteine has the following structural formula:

This product contains the following inactive ingredients:
disodium edetate, sodium hydroxide and water for injection.

The viscosity of pulmonary mucous secretions depends on the concentrations of mucoprotein and, to a lesser extent, deoxyribonucleic acid (DNA). The latter increases with increasing purulence owing to the presence of cellular debris. The mucolytic action of acetylcysteine is related to the sulfhydryl group in the molecule. This group probably ``opens′′ disulfide linkages in mucus thereby lowering the viscosity. The mucolytic activity of acetylcysteine is unaltered by the presence of DNA, and increases with increasing pH. Significant mucolysis occurs between pH 7 and 9.

Acetylcysteine undergoes rapid deacetylation in vivo to yield cysteine or oxidation to yield diacetylcystine.

Occasionally, patients exposed to the inhalation of an acetylcysteine aerosol respond with the development of increased airways obstruction of varying and unpredictable severity. Those patients who are reactors cannot be identified a priori from a random patient population. Even when patients are known to have reacted previously to the inhalation of an acetylcysteine aerosol, they may not react during a subsequent treatment. The converse is also true; patients who have had inhalation treatments of acetylcysteine without incident may still react to subsequent inhalation with increased airways obstruction. Most patients with bronchospasm are quickly relieved by the use of a bronchodilator given by nebulization. If bronchospasm progresses, the medication should be discontinued immediately.

Acetylcysteine is indicated as adjuvant therapy for patients with abnormal, viscid, or inspissated mucous secretions in such conditions as:

Chronic bronchopulmonary disease (chronic emphysema, emphysema with bronchitis, chronic asthmatic bronchitis, tuberculosis, bronchiectasis and primary amyloidosis of the lung)
Acute bronchopulmonary disease (pneumonia, bronchitis, tracheobronchitis)
Pulmonary complications of cystic fibrosis
Tracheostomy care
Pulmonary complications associated with surgery
Use during anesthesia
Post-traumatic chest conditions
Atelectasis due to mucous obstruction
Diagnostic bronchial studies (bronchograms, bronchospirometry, and bronchial wedge catheterization)

Acetylcysteine is contraindicated in those patients who are sensitive to it.

After proper administration of acetylcysteine, an increased volume of liquified bronchial secretions may occur. When cough is inadequate, the 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. Asthmatics under treatment with acetylcysteine should be watched carefully. Most patients with bronchospasm are quickly relieved by the use of a bronchodilator given by nebulization. If bronchospasm progresses, the medication should be discontinued immediately.

Adverse effects have included stomatitis, nausea, vomiting, fever, rhinorrhea, drowsiness, clamminess, chest tightness, and bronchoconstriction. Clinically overt acetylcysteine induced bronchospasm occurs infrequently and unpredictably even in patients with asthmatic bronchitis or bronchitis complicating bronchial asthma.

Acquired sensitization to acetylcysteine has been reported rarely. Reports of sensitization in patients have not been confirmed by patch testing. Sensitization has been confirmed in several inhalation therapists who reported a history of dermal eruptions after frequent and extended exposure to acetylcysteine.

Reports of irritation to the tracheal and bronchial tracts have been received and although hemoptysis has occurred in patients receiving acetylcysteine such findings are not uncommon in patients with bronchopulmonary disease and a causal relationship has not been established.

(Antidotal) Acetaminophen is rapidly absorbed from the upper gastrointestinal tract with peak plasma levels occurring between 30 and 60 minutes after therapeutic doses and usually within 4 hours following an overdose. The parent compound, which is nontoxic, is extensively metabolized in the liver to form principally the sulfate and glucuronide conjugates which are also nontoxic and are rapidly excreted in the urine. A small fraction of an ingested dose is metabolized in the liver by the cytochrome P-450 mixed function oxidase enzyme system to form a reactive, potentially toxic, intermediate metabolite which preferentially conjugates with hepatic glutathione to form the nontoxic cysteine and mercapturic acid derivatives which are then excreted by the kidney. Therapeutic doses of acetaminophen do not saturate the glucuronide and sulfate conjugation pathways and do not result in the formation of sufficient reactive metabolite to deplete glutathione stores. However, following ingestion of a large overdose (150 mg/kg or greater) the glucuronide and sulfate conjugation pathways are saturated resulting in a larger fraction of the drug being metabolized via the P-450 pathway. The increased formation of reactive metabolite may deplete the hepatic stores of glutathione with subsequent binding of the metabolite to protein molecules within the hepatocyte resulting in cellular necrosis.

Acetylcysteine has been shown to reduce the extent of liver injury following acetaminophen overdose. Its effectiveness depends on early oral administration, with benefit seen principally in patients treated within 16 hours of the overdose. Acetylcysteine probably protects the liver by maintaining or restoring the glutathione levels, or by acting as an alternate substrate for conjugation with, and thus detoxification of, the reactive metabolite.

Acetylcysteine, administered orally, is indicated as an antidote to prevent or lessen hepatic injury which may occur following the ingestion of a potentially hepatotoxic quantity of acetaminophen.

It is essential to initiate treatment as soon as possible after the overdose and, in any case, within 24 hours of ingestion.

There are no contraindications to oral administration of acetylcysteine in the treatment of acetaminophen overdose.

Generalized urticaria has been observed rarely in patients receiving oral acetylcysteine for acetaminophen overdose. If this occurs or other allergic symptoms appear, treatment with acetylcysteine should be discontinued unless it is deemed essential and the allergic symptoms can be otherwise controlled.

If encephalopathy due to hepatic failure becomes evident, acetylcysteine treatment should be discontinued to avoid further administration of nitrogenous substances. There are no data indicating that acetylcysteine influences hepatic failure, but this remains a theoretical possibility.

Occasionally severe and persistent vomiting occurs as a symptom of acute acetaminophen overdose. Treatment with oral acetylcysteine may aggravate the vomiting. Patients at risk of gastric hemorrhage (eg, esophageal varices, peptic ulcers, etc.) should be evaluated concerning the risk of upper gastrointestinal hemorrhage versus the risk of developing hepatic toxicity, and treatment with acetylcysteine given accordingly.

Dilution of the acetylcysteine (see Preparation of Acetylcysteine for Oral Administration) minimizes the propensity of oral acetylcysteine to aggravate vomiting.

Oral administration of acetylcysteine, especially in the large doses needed to treat acetaminophen overdose, may result in nausea, vomiting and other gastrointestinal symptoms. Rash with or without mild fever has been observed rarely.

The acute ingestion of acetaminophen in quantities of 150 mg/kg or greater may result in hepatic toxicity. However, the reported history of the quantity of a drug ingested as an overdose is often inaccurate and is not a reliable guide to therapy of the overdose. THEREFORE, PLASMA OR SERUM ACETAMINOPHEN CONCENTRATIONS, DETERMINED AS EARLY AS POSSIBLE, BUT NO SOONER THAN 4 HOURS FOLLOWING AN ACUTE OVERDOSE, ARE ESSENTIAL IN ASSESSING THE POTENTIAL RISK OF HEPATOTOXICITY. IF AN ASSAY FOR ACETAMINOPHEN CANNOT BE OBTAINED, IT IS NECESSARY TO ASSUME THAT THE OVERDOSE IS POTENTIALLY TOXIC.

INTERPRETATION OF ACETAMINOPHEN ASSAYS

1.

When results of the plasma acetaminophen assay are available refer to the nomogram below to determine if plasma concentration is in the potentially toxic range. Values above the solid line connecting 200 mcg/mL at 4 hours with 50 mcg/mL at 12 hours are associated with a possibility of hepatic toxicity if an antidote is not administered. (Do not wait for assay results to begin acetylcysteine treatment.)

2.

If the predetoxification plasma level is above the broken line continue with maintenance doses of acetylcysteine. It is better to err on the safe side and thus the broken line is placed 25% below the solid line which defines possible toxicity.

3.

If the predetoxification plasma level is below the broken line described above, there is minimal risk of hepatic toxicity and acetylcysteine treatment can be discontinued.

Assay procedures most suitable for determining acetaminophen concentrations utilize high pressure liquid chromatography (HPLC) or gas liquid chromatography (GLC). The assay should measure only parent acetaminophen and not conjugated. The assay procedures listed below fulfill this requirement:

HPLC:

1.

Blair D, Rumack, BH, Clin Chem, 1977; 23(4):743-745.

2.

Howie D, Andriaenssens Pl, Prescott LF. J. Pharm Pharmacol, 1977; 29(4):235-237. GLC

3.

Prescott LF. J. Pharm Pharmacol, 1971; 23(10):807-808. Colorimetric

4.

Glynn JP. Kendal SE, Lancet 1975; 1(May 17):1147-1148.

Doses in relation to body weight are:

Estimating Potential for Hepatoxicity

The following nomogram has been developed to estimate the probability that plasma levels in relation to intervals post ingestion will result in hepatoxicity.

Plasma or Serum Acetaminophen Concentration v Time Post-acetaminophen Ingestion

Acetylcysteine is available in rubber stoppered glass vials containing 4, 10, or 30 mL. The 20% solution may be diluted to a lesser concentration with either Sodium Chloride for Injection, Sodium Chloride for Inhalation, Sterile Water for Injection, or Sterile Water for Inhalation. The 10% solution may be used undiluted.

Acetylcysteine solution is sterile and can be used for inhalation (mucolytic agent) or oral administration (acetaminophen antidote). Acetylcysteine solution is not for parenteral injection.  It is available as:

Acetylcysteine 20% solution (200 mg acetylcysteine per mL). Sterile, not for injection.

NDC 55154-5731-5           Overbagged with five 4 mL vials

Acetylcysteine 10% solution (100 mg acetylcysteine per mL). Sterile, not for injection.

NDC 55154-5730-5           Overbagged with five 4 mL vials

Store unopened vials at 20°-25°C (68°-77°F); excursions permitted to 15°-30°C (59°-86°F) (see USP Controlled Room Temperature).

Acetylcysteine solution does not contain an antimicrobial agent, and care must be taken to minimize contamination of the sterile solution. Dilutions of acetylcysteine should be used freshly prepared and utilized within one hour. If only a portion of the solution in a vial is used, store the remaining undiluted portion in a refrigerator and use within 96 hours.  A change in color may occur after opening.  This does not change the efficacy of the drug.

1.

Bonanomi L, Gazzaniga A. Toxicological, pharmacokinetic and metabolic studies on acetylcysteine. Eur J Respir Dis, 1981; 61 (Suppl III): 45-51.

2.

Am Rev Respir Dis, 1960; 82:627-639.

Rx Only

IN7504
Rev. 5/14
MG #11105

AMERICAN
REGENT, INC.
SHIRLEY, NY 11967

Distributed By:

Cardinal Health

Dublin, OH 43017

L35753541118

L35753390218

Acetylcysteine Solution, USP

10% (100 mg/ml)

5 x 4 ml Vials

Acetylcysteine Solution, USP

20% (200 mg/ml)

5 x 4 ml Vials