<p><strong>Effect on ability to drive or operate machinery</strong>: There is no evidence that Zafirlukast affects the ability to drive and use machinery. Administration of Zafirlukast in clinical trials against placebo has been associated with headache (9.9% vs. 9.0%) or gastrointestinal disturbance (nausea 2.6% vs. 2.2%, vomiting 1.2% vs. 1.0%, diarrhoea 2.3% vs. 1.8%, abdominal pain 1.6% vs. 1.2%). These symptoms are usually mild and do not necessitate withdrawal from therapy. During post-marketing experience, bruising, bleeding disorders, including menorrhagia (rare), thrombocytopaenia and agranulocytosis (very rare) have also been reported.<br />
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Hypersensitivity reactions, including urticaria and angio-oedema have been reported. Rashes, including blistering, have also been reported. The above events have usually resolved during continued treatment or following cessation of therapy.<br />
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Infrequently, elevated serum transaminase levels have been observed in clinical trials against placebo with Zafirlukast (increased AST 1.0% vs. 0.9%, increased AST 0.6% vs. 0.6%); at recommended doses the incidence was equivalent to placebo. Rarely the transaminase profile has been consistent with drug-induced hepatitis, which resolved following cessation of Zafirlukast therapy. During post-marketing experience there have been rare reports of hepatitis, with or without elevated bilirubin levels. These cases were usually reversible.<br />
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In placebo controlled clinical trials, an increased incidence of infection has been observed in elderly patients given Zafirlukast (7.8% vs. 1.4%). Infections were usually mild, predominantly affecting the respiratory tract.</p>