1 INDICATIONS AND USAGE Acetylcysteine Injection is indicated to prevent or lessen hepatic injury after ingestion of a potentially hepatotoxic quantity of acetaminophen in patients with acute ingestion or from repeated supratherapeutic ingestion (RSI).

Acetylcysteine Injection is an antidote for acetaminophen overdose indicated to prevent or lessen hepatic injury after ingestion of a potentially hepatotoxic quantity of acetaminophen in patients with an acute ingestion or from repeated supratherapeutic ingestion (RSI) ( 1 ).

6 ADVERSE REACTIONS Most common adverse reactions (> 2%) are rash, urticaria/facial flushing and pruritus ( 6.1 ).

To report SUSPECTED ADVERSE REACTIONS, contact Sagent Pharmaceuticals, Inc.

at 1-866-625-1618 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch .

6.1 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 21%, and they most commonly occur during the initial loading dose of acetylcysteine.

Loading Dose/Infusion Rate Study In a randomized, open-label, multi-center clinical study conducted in Australia in patients with acetaminophen poisoning, the rates of hypersensitivity reactions between a 15-minute and 60-minute intravenous infusion for the 150 mg/kg loading dose of acetylcysteine were compared.

The incidence of drug-related adverse reactions occurring within the first 2 hours following acetylcysteine administration is presented in Table 5 .

Overall, 17% of patients developed an acute hypersensitivity reaction (18% in the 15-minute infusion group; 14% in the 60-minute infusion group) [see Warnings and Precautions ( 5.1 ), Clinical Studies ( 14 )] .

Table 5.

Incidence of Drug-Related Adverse Reactions Occurring Within the First 2 Hours Following Study Drug Administration by Preferred Term: Loading Dose/Infusion Rate Study Unkn=Unknown; NOS=not otherwise specified Treatment Group 15-minutes 60-minutes 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 Hypersensitivity 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 Pruritus 1 (1%) 2 (3%) Rash NOS 3 (3%) 2 (2%) 3 (4%) Vascular disorders 2 (2%) 3 (4%) Severity: Unkn Mild Moderate Severe Unkn Mild Moderate Severe Flushing 1 (1%) 1 (1%) 2 (3%) 1 (1%) 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 hypersensitivity reactions in adult (overall incidence 8%) and pediatric (overall incidence 10%) patients is presented in Tables 6 and 7 .

Table 6.

Distribution of Reported Hypersensitivity Reactions in Adult Patients Receiving Intravenous Acetylcysteine Reaction Incidence (%) n=4709 Urticaria/Facial Flushing 6.1% Pruritus 4.3% Respiratory Symptoms* 1.9% Edema 1.6% Hypotension 0.1% Anaphylaxis 0.1% Table 7.

Distribution of Reported Hypersensitivity Reactions in Pediatric Patients Receiving Intravenous Acetylcysteine *Respiratory symptoms are defined as presence of any of the following: cough, wheezing, stridor, shortness of breath, chest tightness, respiratory distress, or bronchospasm.

Reaction Incidence (%) n=1905 Urticaria/Facial Flushing 7.6% Pruritus 4.1% Respiratory Symptoms* 2.2% Edema 1.2% Anaphylaxis 0.2% Hypotension 0.1%