Moxifloxacin Antacids

The nurse encourages patients who receive tlie fluoroquinolone to increase tlieir fluid intaka Norfloxacin and enoxacin are given on an empty stomach (, 1 hour before or 2 hours after meals). Ciprofloxacin and lome-floxacin can be given without r ard to meals. However, tlie manufacturer recommends that the drug be given 2 hours after a meal. Moxifloxacin is given once a day for tlie period pr ribed. If the patient is taking an antacid, moxifloxacin should be administered 4 hours before or 8 hours after the antacid. 

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). 

Administer oral doses of moxifloxacin at least 4 hours before or 8 hours after antacids containing magnesium or aluminum, sucralfate, metal cations such as iron, multivitamin preparations with zinc, or didanosine (chewable/buffered tablets or pediatric powder for oral solution). 

Concurrent treatment with antacids reduces the oral absorption of many quinolones, such as ciprofloxacin and enoxacin (127), moxifloxacin (16), norfloxacin (128), ofloxacin (129), and sparfloxacin (130). 

The systemic availability of moxifloxacin is markedly reduced by the co-administration of antacids that contain magnesium or aluminium, unless administration occurs 2 hours before or 4 hours after moxifloxacin (19,26). An interval of 2 hours before or 4 hours after taking antacids ensures that the effect of the interaction is not clinically relevant. 

Information about the interactions with calcium carbonate is more limited than with the aluminium/magnesium antacids, but Table 10.3 , (p.329) shows that the bioavailabilities of ciprofloxacin and norfloxacin, and to a lesser extent gemifloxacin, can be reduced. These reductions are less than those seen with the aluminium/magnesium antacids, but using ciprofloxacin as a guide a very broad rule-of-thumb would be to separate the drug administration by about 2 hours to minimise this interaction. This is clearly not necessary with levofloxacin, lomefloxacin, moxifloxacin or ofloxacin, nor probably with some of the other qui-... 

Stass H, Bbttcher M-F, Ochmann K. Evaluation of the influence of antacids and H2 antagonists on the absorption of moxifloxacin after oral administration of a 400-mg dose to healthy volunteers. Clin Pharmacokinet (2001) 40 (Suppl 1), 39-48. 

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