Gatifloxacin arrhythmia with

The incidence of serious cardiac arrhythmia with the use of fluoroquinolones was investigated in a retrospective, nested case-controlled study. Fluoroquinolones were associated witir an increased risk of serious cardiac arrhythmia (RR 1.76) with gatifloxacin giving the highest risk (RR7.38), followed by moxifloxacin (RR 3.30) and ciprofloxacin (RR 2.15) [20 ]. Hypersensitivity reactions to fluoroquinolones are more likely in subjects who have had a previous reaction to beta-lactam antibiotics (OR 4.57) [21 ]. 

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). 

Torsade de pointes has been reported in two patients taking amiodarone and levofloxacin. Post-marketing surveillance identifled two cases with amiodarone and sparfloxacin. An increased risk of this arrhythmia would also be expected if amiodarone is used with gatifloxacin or moxifloxacin. 

Of the quinolones used clinically, gatifloxacin, moxifloxacin, and sparfloxacin are known to prolong the QT interval (see Table 9.2 , (p.257)) and would be expected to increase the risk of torsade de pointes arrhythmias when used with procainamide. These quinolones should probably be avoided in patients on procainamide (see also Drugs that prolong the QT interval + Other drugs that prolong the QT interval , p.257). 

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