Acetylcysteine Injection: Indications, Dosage, Precautions, Adverse Effects
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Acetylcysteine Injection - Product Information

Manufacture: Fresenius Kabi USA, LLC
Country: United States
Condition: Acetaminophen Overdose, Diagnostic Bronchograms, Expectoration (Mucolysis)
Class: Antidotes
Form: Liquid solution, Intravenous (IV)
Ingredients: acetylcysteine, disodium edetate, sodium hydroxide (used for pH adjustment), water for injection

Indications and Usage

Acetylcysteine Injection is an antidote for acetaminophen overdose indicated to prevent or lessen hepatic injury after ingestion of a potentially hepatotoxic quantity of acetaminophen. Overdose incidences are divided into two types; Acute Ingestion or Repeated Supratherapeutic Ingestion (RSI). [see Dosage and Administration and Acetaminophen Assays – Interpretation and Methodology -(Acute or Repeated Supratherapeutic Ingestion)].

On admission for suspected acetaminophen overdose, a serum blood sample should be drawn at least 4 hours after ingestion to determine the acetaminophen level and will serve as a basis for determining the need for treatment with acetylcysteine. If the patient presents after 4 hours post-ingestion, the serum acetaminophen sample should be determined immediately.

Acetylcysteine Injection should be administered within 8 hours from acetaminophen ingestion for maximal protection against hepatic injury for patients whose serum acetaminophen levels fall above the "possible" toxicity line on the Rumack-Matthew nomogram (line connecting 150 mcg/mL at 4 hours with 37.5 mcg/mL at 12 hours); [see Acetaminophen Assays – Interpretation and Methodology]. If the time of ingestion is unknown, or the serum acetaminophen level is not available, cannot be interpreted, or is not available within the 8 hour time interval from acetaminophen ingestion, Acetylcysteine Injection should be administered immediately if 24 hours or less have elapsed from the reported time of ingestion of an overdose of acetaminophen, regardless of the quantity reported to have been ingested.

The aspartate aminotransferase (AST, SGOT), alanine aminotranferase (ALT, SGPT), bilirubin, prothrombin time, creatinine, blood urea nitrogen (BUN), blood glucose, and electrolytes also should be determined in order to monitor hepatic and renal function and electrolyte and fluid balance.

NOTE: The critical ingestion-treatment interval for maximal protection against severe hepatic injury is between 0 to 8 hours. Efficacy diminishes progressively after 8 hours and treatment initiation between 15 and 24 hours post-ingestion of acetaminophen yields limited efficacy. However, it does not appear to worsen the condition of patients and it should not be withheld, since the reported time of ingestion may not be correct.

Acetaminophen Assays Interpretation and Methodology – Acute Ingestion

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 four 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 in Figure 1 to determine if plasma concentration is in the potentially toxic range. Values above the line connecting 200 mcg/mL at 4 hours with 50 mcg/mL at 12 hours (probable line) are associated with a probability of hepatic toxicity if an antidote is not administered.
  2. If the predetoxification plasma level is above the line connecting 150 mcg/mL at 4 hours with 37.5 mcg/mL at 12 hours (possible line), continue with maintenance doses of acetylcysteine. It is better to err on the safe side and thus this line, defining possible toxicity, is plotted 25% below the line defining probable toxicity.
  3. If the predetoxification plasma level is below the line connecting 150 mcg/mL at 4 hours with 37.5 mcg/mL at 12 hours (possible line), there is minimal risk of hepatic toxicity, and Acetylcysteine treatment may be discontinued.

Estimating Potential for Hepatotoxicity: The following depiction of the Rumack- Matthew nomogram has been developed to estimate the probability that plasma levels in relation to intervals post-ingestion will result in hepatotoxicity.

The Rumack-Matthew nomogram may underestimate the risk for hepatotoxicity in some patients with risk factors such as chronic alcoholism, malnutrition, or CYP2E1 enzyme inducing drugs (e.g., isoniazid).

Figure 1. Rumack-Matthew Nomogram


Figure 1. Michael J Hodgman, Alexander R Garrard, A Review of Acetaminophen Poisoning. Crit Care Clin. 28 (2012) 499-516. Stephen J. Wolf, Kennon Heard, et.al, Clinical Policy: Critical Issues in the Management of Patients Presenting to the Emergency Department with Acetaminophen Overdose. Ann Emerg Med. 2007:50:292-313.

Acetaminophen Assays Interpretation and Methodology – Repeated Supratherapeutic Ingestion

Repeated Supratherapeutic Ingestion (RSI) is defined as ingestion of acetaminophen at doses higher than those recommended for extended periods of time. The nomogram does not apply to patients with RSI. Treatment is based on the acetaminophen and elevated AST/ALT levels indicative of potential toxicity due to acetaminophen. For specific treatment information regarding the clinical management of repeated supratherapeutic acetaminophen overdose, please contact your regional poison center at 1-800-222-1222, or alternatively, a special health professional assistance line for acetaminophen overdose at 1-800-525-6115.

Figure 2. Acetylcysteine Injection Treatment Flow Chart


1Acetaminophen levels drawn less than 4 hours post-ingestion may be misleading.

2With an extended-release preparation, an acetaminophen level drawn less than 8 hours post-ingestion may be misleading. Draw a second level at 4 to 6 hours after the initial level. If either falls above the toxicity line, acetylcysteine treatment should be initiated.

3Acetylcysteine may be withheld until acetaminophen assay results are available as long as initiation of treatment is not delayed beyond 8 hours post-ingestion. If more than 8 hours post-ingestion, start acetylcysteine treatment immediately.

Dosage and Administration

The total dose of Acetylcysteine Injection is 300 mg/kg given as 3 separate doses and administered over a total of 21 hours. Please refer to the guidelines below for dose preparation based upon patient weight. The total volume administered should be adjusted for patients less than 40 kg and for those requiring fluid restriction (see Tables 1 and 2).

Administration Instructions (Three-Bag Method: Loading, Second and Third Dose)

Dosing for Patients who weigh 5 kg to 20 kg ( Table 1)

Loading Dose: 150 mg/kg diluted in 3 mL/kg of diluent* administered or

Second Dose: 50 mg/kg diluted in 7 mL/kg of diluent* administered ovs

Third Dose: 100 mg/kg diluted in 14 mL/kg of diluent* administered oves

Table 1. Three Bag Method Dosage Guide by Weight in Patients 5 kg to 20 kg
Body Weight (kg) Bag 1 (loading dose):
150 mg/kg in 3 mL/kg of diluent*
infused over 1 hour
Bag 2 (second dose):
50 mg/kg in 7mL/kg of diluent*
infused over 4 hours
Bag 3 (third dose):
100 mg/kg diluted in 14 mL/kg of diluent* 
infused over 16 hours
Acetylcysteine Injection Total Dose Diluent volume Acetylcysteine Injection Total Dose Diluent volume Acetylcysteine Injection Total Dose Diluent volume
5 kg 750 mg 15 mL 250 mg 35 mL 500 mg 70 mL
10 kg 1,500 mg 30 mL 500 mg 70 mL 1,000 mg 140 mL
15 kg 2,250 mg 45 mL 750 mg 105 mL 1,500 mg 210 mL
20 kg 3,000 mg 60 mL 1,000 mg 140 mL 2,000 mg 280 mL

* Acetylcysteine Injection is compatible with the following diluents; 5% Dextrose in Water, 0.4 5% Sodium Chloride Injection, and Sterile Water for Injection.

See also Section Volume Adjustment: Patients less than 40 kg and Requiring Fluid Restriction

Dosing for patients who weigh 21 kg to 40 kg ( Table 2)

Loading Dose: 150 mg/kg diluted in 100 mL of diluent* administered or

Second Dose: 50 mg/kg diluted in 250 mL of diluent* administered ovs

Third Dose: : 100 mg/kg diluted in 500 mL of diluent* administered oves

Table 2. Three Bag Method Dosage Guide by Weight in Patients 21 kg to 40 kg
Body Weight (kg) Bag 1 (loading dose): 150 mg/kg in 100 mL of diluent*
infused over 1 hr
Bag 2 (second dose): 50 mg/kg in 250 mL of diluent* 
infused over 4 hrs
Bag 3 (third dose): 100 mg/kg in 500 mL of diluent* 
infused over 16 hrs
Acetylcysteine Injection Total Dose Acetylcysteine Injection Total Dose Acetylcysteine Injection Total Dose
21 kg 3,150 mg 1,050 mg 2,100 mg
30 kg 4,500 mg 1,500 mg 3,000 mg
40 kg 6,000 mg 2,000 mg 4,000 mg

* Acetylcysteine Injection is compatible with the following diluents; 5% Dextrose in Water 0.4 5% Sodium Chloride Injection, and Sterile Water for Injection.

See also Section Volume Adjustment: Patients less than 40 kg and Requiring Fluid Restriction.

Dosing for patients who weigh 41 kg to 100 kg ( Table 3)

Loading Dose: 150 mg/kg diluted in 200 mL of diluent* administered or

Second Dose: 50 mg/kg diluted in 500 mL of diluent* administered ovs

Third Dose: 100 mg/kg diluted in 1,000 mL of diluent administered oves

Table 3. Three Bag Method Dosage Guide by Weight in Patients 41 kg to 100 kg
Body Weight (kg) Bag 1 (loading dose): 150 mg/kg diluted in 200 mL of diluent*
infused over 1 hr
Bag 2 (second dose): 50 mg/kg diluted in 500 mL of diluent*
infused over 4 hrs
Bag 3 (third dose): 100 mg/kg diluted in 1,000 mL of diluent*
infused over 16 hrs
Acetylcysteine Injection Total Dose Acetylcysteine Injection Total Dose Acetylcysteine Injection Total Dose
41 kg 6,150 mg 2,050 mg 4,100 mg
50 kg 7,500 mg 2,500 mg 5,000 mg
60 kg 9,000 mg 3,000 mg 6,000 mg
70 kg 10,500 mg 3,500 mg 7,000 mg
80 kg 12,000 mg 4,000 mg 8,000 mg
90 kg 13,500 mg 4,500 mg 9,000 mg
100 kg 15,000 mg 5,000 mg 10,000 mg

* Acetylcysteine Injection is compatible with the following diluents; 5% Dextrose 0.4 5% Sodium Chloride Injection, and Sterile Water for Injection.

Patients Weighing More Than 100 kg

No specific studies have been conducted to evaluate the use of or necessity of dosing adjustments in patients weighing over 100 kg. Limited information is available regarding the dosing requirements of patients that weigh more than 100 kg. The dose of Acetylcysteine Injection recommended in these patients should be a loading dose of 15,000 mg
infused over a period of one hour followed by a first maintenance dose of 5,000 mg over 4 hours and a second maintenance dose of 10,000 mg over 16 hours ( Table 3).

Continued Therapy beyond 21 Hours

While there is no clinical trial data to support infusions beyond 21 hours there is literature that supports continued infusion of acetylcysteine in some rare instances. In cases of suspected massive overdose, or with concomitant ingestion of other substances, or in patients with preexisting liver disease, the absorption and/or the half-life of acetaminophen may be prolonged, in such cases consideration should be given to the need for continued infusion of N-acetylcysteine beyond 21 hours. Acetaminophen levels and ALT/AST & INR should be checked before the end of the 21-hour infusion. If acetaminophen levels are still detectable, or in cases in which the ALT/AST are still increasing or the INR remains elevated, the infusion should be continued, and the treating physician should contact a US regional poison center at 1-800-222-1222, or alternatively, a “special health professional assistance line for acetaminophen overdose” at 1-800-525-6115 for assistance with dosing recommendations.

Volume Adjustment: Patients less than 40 kg and Requiring Fluid Restriction

The total volume administered should be adjusted for patients less than 40 kg and for those requiring fluid restriction. To avoid fluid overload, the volume of diluent should be reduced as clinically needed. If the volume of the infusion is not adjusted, fluid overload can occur, potentially resulting in hyponatremia, seizure and death. [ see Dosage and Administration]

As Acetylcysteine Injection is hyperosmolar (2600 mOsmol/L), caution is advised when the diluent volume is decreased as the hyperosmolarity of the solution is increased. See Table 4 below for examples.

Table 4. Acetylcys teine Injection Concentration and Osmolarity
Acetylcysteine Injection Concentration (mg/mL) Osmolarity in ½ Normal Saline Osmolarity in D5W Osmolarity in Sterile Water for Injection
7 mg/mL 245 mOsmol/L 343 mOsmol/L 91 mOsmol/L *
24 mg/m/L 466 mOsmol/L 564 mOsmol/L 312 mOsmol/L

* Osmolarity should be adjusted to a physiologically safe level, (generally not less than 150mOsmol/L in children).

Single dose vial, preservative-free, discard unused portion. If vial was previously opened, do not use for intravenous administration.

Stability studies indicate that the diluted solution is stable for 24 hours at controlled room temperature.

Note: The color of Acetylcysteine Injection may turn from essentially colorless to a slight pink or purple once the stopper is punctured. The color change does not affect the quality of the product.

Renal Impairment

No data are available to determine if a dose adjustment in patients with moderate or severe renal impairment is required.

Hepatic Impairment

Although there was a threefold increase in acetylcysteine plasma concentrations in patients with hepatic cirrhosis, no data are available to determine if a dose adjustment in these patients is required. The published medical literature does not indicate that the dose of acetylcysteine in patients with hepatic impairment should be reduced.

Dosage Forms and Strengths

Each single dose vial contains 6g/30mL (200 mg/mL) of Acetylcysteine. Acetylcysteine Injection is sterile and can be used for intravenous administration.

Contraindications

Acetylcysteine Injection is contraindicated in patients with previous anaphylactoid reactions to acetylcysteine.

Warnings and Precautions

Anaphylactoid Reactions

Serious anaphylactoid reactions, including death in a patient with asthma, have been reported in patients administered acetylcysteine intravenously.
Acute flushing and erythema of the skin may occur in patients receiving acetylcysteine intravenously. These reactions usually occur 30 to 60 minutes after initiating the infusion and often resolve spontaneously despite continued infusion of acetylcysteine. Anaphylactoid reactions (defined as the occurrence of an acute hypersensitivity reaction during acetylcysteine administration including rash, hypotension, wheezing, and/or shortness of breath) have been observed in patients receiving intravenous acetylcysteine for acetaminophen overdose and occurred soon after initiation of the infusion [see ADVERSE REACTIONS].If a reaction to acetylcysteine involves more than simply flushing and erythema of the skin, it should be treated as an anaphylactoid reaction. This usually entails administering antihistaminic drugs and in severe cases may require administration of epinephrine. In addition, the acetylcysteine infusion may be interrupted until treatment of the anaphylactoid symptoms has been initiated and then carefully restarted. If the anaphylactoid reaction returns upon reinitiation of treatment or increases in severity, intravenous acetylcysteine should be discontinued and alternative patient management should be considered.

Monitoring Patients with Asthma

Acetylcysteine Injection should be used with caution in patients with asthma, or where there is a history of bronchospasm.

Volume Adjustment: Patients less than 40 kg and Requiring Fluid Restriction

The total volume administered should be adjusted for patients less than 40 kg and for those requiring fluid restriction. To avoid fluid overload, the volume of diluent should be reduced as needed [see DOSAGE AND ADMINISTRATION]. If volume is not adjusted fluid overload can occur, potentially resulting in hyponatremia, seizure and death.

For specific treatment information regarding the clinical management of acetaminophen overdose, please contact your regional poison center at 1-800-222-1222, or alternatively, a special health professional assistance line for acetaminophen overdose at 1-800-525-6115.

Adverse Reactions

Clinical Studies Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

In the literature the most frequently reported adverse reactions attributed to intravenous acetylcysteine administration were rash, urticaria and pruritus. The frequency of adverse reactions has been reported to be between 0.2% and 20.8%, and they most commonly occur during the initial loading dose of acetylcysteine.

Loading Dose/Infusion Rate Study

The incidence of drug-related adverse reactions occurring within the first 2 hours following acetylcysteine administration reported in a randomized study in patients with acetaminophen poisoning is presented in Table 5 by preferred term. In this study patients were randomized to a 15-minute or a 60-minute loading dose regimen.

Within the first 2 hours following intravenous acetylcysteine administration, 17% developed an anaphylactoid reaction (18% in the 15-minute treatment group; 14% in the 60-minute treatment group) in this randomized, open-label, multi-center clinical study conducted in Australia to compare the rates of anaphylactoid reactions between two rates of infusion for the intravenous acetylcysteine loading dose [ see WARNINGS and CLINACAL STUDIES - Loading Dose/InfusionRate Study].

Table 5. Incidence of Drug-Related Advers e Reactions Occurring Within the Firs t 2 Hours Following Study Drug Adminis tration by Preferred Term: Loading Dos e/Infus ion Rate Study
Treatment Group 15-min 60-min
Number of Patients n=109 n=71
Cardiac disorders 5 (5%) 2 (3%)
Severity: Unkn Mild Moderate Severe Unkn Mild Moderate Severe
Tachycardia NOS   4 (4%) 1 (1%)     2 (3%)    
Gastrointestinal disorders 16 (15%) 7 (10%)
Severity: Unkn Mild Moderate Severe Unkn Mild Moderate Severe
Nausea 1(1%)   6 (6%)     1 (1%) 1 (1%)  
Vomiting NOS   2 (2%) 11 (10%)     2 (3%) 4 (6%)  
Immune System Disorders 20 (18%) 10 (14%)
Severity: Unkn Mild Moderate Severe Unkn Mild Moderate Severe
Anaphylactoid reaction 2(2%) 6 (6%) 11 (10%) 1 (1%)   4 (6%) 5 (7%) 1 (1%)
Respiratory, thoracic and mediastinal
disorders
2 (2%) 2 (3%)
Severity: Unkn Mild Moderate Severe Unkn Mild Moderate Severe
Pharyngitis     1 (1%)          
Rhinorrhoea   1 (1%)            
Rhonchi           1 (1%)    
Throat tightness           1 (1%)    
Skin & subcutaneous tissue disorders 6 (6%) 5 (7%)
Severity: Unkn Mild Moderate Severe Unkn Mild Moderate Severe
Flushing   1 (1%) 1 (1%)     2 (3%) 1 (1%)  

Postmarketing Safety Study

A large multi-center study was performed in Canada where data were collected from patients who were treated with intravenous acetylcysteine for acetaminophen overdose between 1980 and 2005. This study evaluated 4709 adult cases and 1905 pediatric cases. The incidence of anaphylactoid reactions in adult (overall incidence 7.9%) and pediatric (overall incidence 9.5%) patients is presented in Tables 6 and 7.

Table 6.Dis tribution of reported reactions in adult patients receiving intravenous acetylcys teine
  Incidence
(%)
Reaction % of
Patients
(n=4709)
Urticaria/Facial Flushing 6.1%
Pruritus 4.3%
Respiratory Symptoms * 1.9%
Edema 1.6%
Hypotension 0.1%
Anaphylaxis 0.1%

* Respiratory symptoms are defined as presence of any of the following: cough, wheezing, stridor, shortness of breath, chest tightness, respiratory distress, or bronchospasm.

Table 7 Dis tribution of reported reactions in pediatric patients receiving
intravenous acetylcys teine
  Incidence
(%)
Reaction % of
Patients
(n=1905)
Urticaria/Facial Flushing 7.6%
Pruritus 4.1%
Respiratory Symptoms* 2.2%
Edema 1.2%
Anaphylaxis 0.2%
Hypotension 0.1%

* Respiratory symptoms are defined as presence of any of the following: cough, wheezing, stridor, shortness of breath, chest tightness, respiratory distress, or bronchospasm.

Drug Interactions

No drug-drug interaction studies have been conducted.

Use in Specific Populations

Pregnancy

Pregnancy Category B

There are no adequate and well-controlled studies of Acetylcysteine Injection in pregnant women. However, limited case reports of pregnant women exposed to acetylcysteine during various trimesters did not report any adverse maternal, fetal or neonatal outcomes.

There are published reports on four pregnant women with acetaminophen toxicity, who were treated with oral or intravenous acetylcysteine at the time of delivery. Acetylcysteine crossed the placenta and was measurable following delivery in serum and cord blood of three viable infants and in cardiac blood of a fourth infant at autopsy (22 weeks gestational age who died 3 hours after birth). No adverse sequelae developed in the three viable infants. All mothers recovered and none of the infants had evidence of acetaminophen poisoning.

Reproduction studies were performed in rats at oral doses up to 2,000 mg/kg/day (1.1 times the recommended total human intravenous dose of 300 mg/kg based on body surface area comparison) and in rabbits at oral doses up to 1,000 mg/kg/day (1.1 times the recommended total human intravenous dose of 300 mg/kg based on body surface area comparison). No effects on fertility or harm to the fetus due to acetylcysteine were observed.

Nursing Mothers

It is not known whether Acetylcysteine Injection is present in human milk. Because many drugs are excreted in human milk, caution should be exercised when acetylcysteine is administered to a nursing woman. Based on the pharmacokinetics of acetylcysteine, it should be nearly completely cleared 30 hours after administration. Nursing women may consider resuming nursing 30 hours after administration.

Pediatric Use

No adverse effects were noted during intravenous infusion with acetylcysteine at a mean rate of 4.2 mg/kg/h for 24 hours to 10 preterm newborns ranging in gestational age from 25 to 31 weeks and in weight from 500 to 1380 grams in one study or in 6 newborns ranging in gestational age from 26 to 30 weeks and in weight from 520 to 1335 grams infused with acetylcysteine at 0.1 to 1.3 mg/kg/h for 6 days. Elimination of acetylcysteine was slower in these infants than in adults; mean elimination half-life was 11 hours. There are no adequate and well-controlled studies in pediatric patients.

Geriatric Use

The clinical studies do not provide a sufficient number of geriatric subjects to determine whether the elderly respond differently.

Overdosage

Single intravenous doses of acetylcysteine at 1000 mg/kg in mice, 2445 mg/kg in rats, 1500 mg/kg in guinea pigs, 1200 mg/kg in rabbits and 500 mg/kg in dogs were lethal. Symptoms of acute toxicity were ataxia, hypoactivity, labored respiration, cyanosis, loss of righting reflex and convulsions.

How Supplied/Storage and Handling

Acetylcysteine Injection is available as a 20% solution (200 mg/mL) in 30 mL single dose glass vials. Each single dose vial contains 6 g/30 mL (200 mg/mL) of Acetylcysteine. Acetylcysteine Injection is sterile and can be used for intravenous administration.

Acetylcysteine Injection is available as:

Product NoNDC NoStrength
96303063323-963-30200 mg per mL 20% solution (200 mg per mL) in 30 mL single dose glass vials, packaged in cartons of 4

Do not use previously opened vials for intravenous administration.

Note: The color of Acetylcysteine Injection may turn from essentially colorless to a slight pink or purple once the stopper is punctured. The color change does not affect the quality of the product.

The stopper in the Acetylcysteine Injection vial is formulated with a synthetic base-polymer and does not contain Natural Rubber Latex, Dry Natural Rubber, or blends of Natural Rubber.

Storage

Store unopened vials at controlled room temperature, 20° to 25°C (68° to 77°F) [see USP Controlled Room Temperature].

Patient Counseling Information

Sensitivity to acetylcysteine: Patients should be advised to report to their physician any history of sensitivity to acetylcysteine [ see CONTRAINDICATIONS]

Asthma: Patients should be advised to report to their physician any history of asthma [ see WARNINGS AND PRECAUTIONS]

For all questions concerning adverse reactions associated with the use of this product or for Inquiries concerning our products, please contact us at 1-800-551-7176.

For specific treatment information regarding the clinical management of acetaminophen overdose, please contact your regional poison center at 1-800-222-1222, or alternatively, a special health professional assistance line for acetaminophen overdose at 1-800-525-6115.

Manufactured For

Fresenius Kabi USA, LLC
Lake Zurich, IL 60047
Made in India
451234A/Revised: December 2014