Gatifloxacin Theophylline

Concurrent use of the fluoroquinolones with theophylline causes an increase in serum theophylline levels. When used concurrently with cimetidine, the cimetidine may interfere with the elimination of the fluoroquinolones. Use of the fluoroquinolones with an oral anticoagulant may cause an increase in the effects of the oral coagulant. Administration of the fluoroquinolones with antacids, iron salts, or zinc will decrease absorption of the fluoroquinolones. There is a risk of seizures if fluoroquinolones are given with the NSAIDs. There is a risk of severe cardiac arrhythmias when the fluoroquinolones gatifloxacin and moxifloxacin are administered with drains that increase the QT interval (eg, quini-dine, procainamide, amiodarone, and sotalol). 

Theophylline [P] Ciprofloxacin, enoxacin, and, to a lesser extent, norfloxacin inhibit theophylline metabolism gatifloxacin, levofloxacin, lomefloxacin, ofloxacin, and sparfloxacin appear to have little effect. 

Theophylline serum levels can be markedly increased in most patients by enoxacin. Pipemidic acid and clinafloxacin probably interact similarly. Theophylline levels can also be markedly increased in some patients by ciprofloxacin, and possibly pe-floxacin. Norfloxacin, ofloxacin, pazufloxacin, or prulifloxacin normally cause a much smaller rise in theophylline levels. However, serious toxicity has been seen in few patients given norfloxacin. Fleroxacin, flumequine, gatifloxacin, gemifloxacin, levofloxacin, lomefloxacin, moxifloxacin, nalidixic acid, rufloxacin, spar-floxacin and trovafloxacin appear not to interact. 

Stahlberg HJ, Gohler K, Guillaume M, Mignot A. Effects of gatifloxacin (GTX) on the pharmacokinetics of theophylline in healthy young volunteers. J Antimicrob Chemother (1999) 44 (Suppl A), 136. 

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