Zileuton dosage

Administration of zafirlukast and aspirin increases plasma levels of zafirlukast, When zafirlukast is administered with warfarin, there is an increased effect of the anti coagulant. Administration of zafirlukast and theophylline or erythromycin may result in a decreased level of zafirlukast. Administration of montelukast with other drugs has not revealed any adverse responses. Administration of montelukast with aspirin and NSAIDs is avoided in patients with known aspirin sensitivity. Administration of zileuton with propranolol increases the activity or the propranolol with theophylline increases serum theophylline levels and with warfarin may increase prothrombin time (PT). A prothrombin blood test should be done regularly in the event dosages of warfarin need to be decreased. 

The recommended dosage of zileuton for the symptomatic treatment of patients with asthma is 600 mg 4 times/day for a total daily dose of 2400 mg. For ease of administration, zileuton may be taken with meals and at bedtime. 

Some patients appear to have particularly favorable responses, but no clinical features allow identification of "responders" before a trial of therapy. In the USA, zileuton is approved for use in an oral dosage of 1200 mg of the sustained-release form twice daily zafirlukast, 20 mg twice daily and montelukast, 10 mg (for adults) or 4 mg (for children) once daily. 

Of these agents, zileuton is the least prescribed because of reports of occasional liver toxicity. The receptor antagonists appear to have little toxicity. Reports of Churg-Strauss syndrome (a systemic vasculitis accompanied by worsening asthma, pulmonary infiltrates, and eosinophilia) appear to have been coincidental, with the syndrome unmasked by the reduction in prednisone dosage made possible by the addition of zafirlukast or montelukast. Of these two, montelukast is the most prescribed, probably because it can be taken without regard to meals and because of the convenience of once-daily treatment. 

Zileuton (255) Potentiation Unknown Adjust dosage Monitor INR... 

Information is limited but the interaction appears to be established and of clinical importance. Concurrent use need not be avoided but monitor theophylline levels and reduce the dosage of theophylline as necessary. The report quoted above suggests that a typical asthma patient may initially need the theophylline dosage to be halved, and this dose reduction is recommended by the US manufacturers. Similarly, the dose of theophylline should be reduced if it is given to a patient already taking zileuton, and adjusted according to theophylline levels. This is based on the results of a study in over 1000 patients taking zileuton 600 mg four times daily without apparent problems when this course of action was followed. ... 

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