Quinidine Gatifloxacin

Cardiac toxicity Moxifloxacin and gatifloxacin have been shown to prolong the QT interval of the electrocardiogram in some patients. Avoid in patients with known prolongation of the QT interval, patients with uncorrected hypokalemia, and patients receiving class lA (eg, quinidine, procainamide) or class III (eg, amiodarone, sotalol) antiarrhythmic agents. 

Clinically important, potentially hazardous interactions with abarelix, acenocoumarol, amisulpride, amprenavir, anisindione, anticoagulants, arsenic, astemizole, carbimazole, celiprolol, ciprofloxacin, dabigatran, degarelix, dicumarol, digoxin, diltiazem, enoxacin, fentanyl, fosamprenavir, gatifloxacin, grapefruit juice, lomefloxacin, methotrexate, moxifloxacin, nilotinib, norfloxacin, ofloxacin, oxprenolol, quinidine, quinolones, rifabutin, rifampin, rifapentine, ritonavir, simvastatin, sparfloxacin, sulpiride, tacrolimus, tipranavir, verapamil, warfarin, zuclopenthixol... 

Clinically important, potentially hazardous interactions with abacavir, amiodarone, bretylium, chlorpromazine, ciprofloxacin, disopyramide, enoxacin, fluphenazine, gatifloxacin, lomefloxacin, mesoridazine, moxifloxacin, norfloxacin, ofloxacin, phenothiazines, procainamide, prochlorperazine, promethazine, quinidine, quinolones, sotalol, sparfloxacin, thioridazine, trifluoperazine... 

Ciprofloxacin normally appears not to interact with quinidine to a clinically relevant extent An increased risk of torsade de pointes might be expected if quinidine is used with gatifloxacin, moxifloxacin, or sparfloxacin, and possibly levofloxacin. 

Some quinolones can prolong the QT interval, and would be expected to increase the risk of torsade de pointes arrhythmias when used with quinidine. Of the quinolones used clinically, gatifloxacin, moxifloxacin, and sparfloxacin are known to prolong the QT interval (see Table 9.2 , (p.257)). There is also evidence that levofloxacin may prolong the QT interval (see Amiodarone + Quinolones , p.249). These quinolones should... 

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