Zafirlukast Disease Interactions

The use of zafirlukast may be associated with elevations of one or more liver enzymes as well as life-threatening hepatic failure. Cases of liver injury without other attributable cause have been reported from postmarketing surveillance of patients treated with the recommended dosage of zafirlukast (40 mg/day). Although most cases have been reversible following drug discontinuation, fulminant hepatitis and progression to hepatic failure, liver transplantation, and death have rarely been reported. In patients with hepatic cirrhosis, serum zafirlukast concentrations may be 50% to 60% higher than in normal patients. Zafirlukast is contraindicated in patients with hepatic impairment including hepatic cirrhosis. Periodic serum transaminase testing is recommended to enable early detection of drug-induced hepatic injury. Patients should be advised to contact their physician immediately if they experience signs or symptoms of liver dysfunction (e.g., right upper quadrant abdominal pain, nausea, fatigue, lethargy, pruritus, jaundice, flu-like symptoms, anorexia, and enlarged liver). Zafirlukast should be discontinued, and liver function tests performed immediately if hepatic injury is suspected. The drug should not be resumed if hepatic injury is confirmed. Patients in whom zafirlukast was withdrawn because of hepatic injury where no other attributable cause is identified should not be re-exposed to zafirlukast.