warnings and cautions
5 WARNINGS AND PRECAUTIONS • Hypersensitivity reactions: Anaphylactic reactions have been reported. Less severe hypersensitivity reactions may also occur. Monitor patients. If a reaction occurs, discontinue MESNEX and provide supportive care. (5.1) • Dermatologic toxicity: Skin rash with eosinophilia and systemic symptoms, Stevens-Johnson syndrome, and toxic epidermal necrolysis have occurred. Skin rash, urticaria, and angioedema have also been seen. Monitor patients. If a reaction occurs, discontinue MESNEX and provide supportive care. (5.2) • Benzyl alcohol toxicity: The preservative benzyl alcohol has been associated with serious adverse reactions and death in neonates and premature infants. Avoid use in neonates, premature, and low-birth weight infants. (5.3) • Laboratory test alterations: False positive tests for urinary ketones and interference with enzymatic CPK activity tests have been seen. (5.4) 5.1 Hypersensitivity Reactions MESNEX may cause systemic hypersensitivity reactions, including anaphylaxis. These reactions may include fever, cardiovascular symptoms (hypotension, tachycardia), acute renal impairment, hypoxia, respiratory distress, urticaria, angioedema, laboratory signs of disseminated intravascular coagulation, hematological abnormalities, increased liver enzymes, nausea, vomiting, arthralgia, and myalgia. These reactions may occur with the first exposure or after several months of exposure. Monitor for signs or symptoms. Discontinue MESNEX and provide supportive care. 5.2 Dermatologic Toxicity Drug rash with eosinophilia and systemic symptoms and bullous and ulcerative skin and mucosal reactions, consistent with Stevens-Johnson syndrome or toxic epidermal necrolysis have occurred. MESNEX may cause skin and mucosal reactions characterized by urticaria, rash, erythema, pruritus, burning sensation, angioedema, periorbital edema, flushing and stomatitis. These reactions may occur with the first exposure or after several months of exposure. Discontinue MESNEX and provide supportive care. 5.3 Benzyl Alcohol Toxicity Benzyl alcohol, a preservative in MESNEX, has been associated with serious adverse reactions and death (including gasping syndrome) in neonates, premature, and low-birth weight infants. The minimum amount of benzyl alcohol at which toxicity may occur is not known. Consider the combined daily metabolic load of benzyl alcohol from all sources when prescribing MESNEX (10.4 mg benzyl alcohol per mL). Neonates, premature, and low-birth weight infants, as well as patients receiving high dosages, may be more likely to develop toxicity. Monitor patients for signs or symptoms of toxicity. Avoid use in neonates, premature, and low-birth weight infants [ See Use in Specific Populations (8.4) ] . 5.4 Laboratory Test Interferences False-Positive Urine Tests for Ketone Bodies A false positive test for urinary ketones may arise in patients treated with MESNEX when using nitroprusside sodium-based urine tests (including dipstick tests). The addition of glacial acetic acid can be used to differentiate between a false positive result (cherry-red color that fades) and a true positive result (red-violet color that intensifies). False-Negative Tests for Enzymatic CPK Activity MESNEX may interfere with enzymatic creatinine phosphokinase (CPK) activity tests that use a thiol compound (e.g., N-acetylcysteine) for CPK reactiviation. This may result in a falsely low CPK level. False-Positive Tests for Ascorbic Acid MESNEX may cause false-positive reactions in Tillman’s reagent-based urine screening tests for ascorbic acid. 5.5 Use in Patients with a History of Adverse Reactions to Thiol Compounds MESNEX is a thiol compound, i.e., a sulfhydryl (SH) group-containing organic compound. Hypersensitivity reactions to MESNEX and to amifostine, another thiol compound, have been reported. It is not clear whether patients who experienced an adverse reaction to a thiol compound are at increased risk for a hypersensitivity reaction to MESNEX.