ADMINISTRATION OF QUINOLONES WITH ANTACIDS CONTAINING ALUMINUM, MAGNESIUM, OR CALCIUM, WITH SUCRALFATE, WITH METAL CATIONS SUCH AS IRON, OR WITH MULTIVITAMINS CONTAINING IRON OR ZINC, OR WITH FORMULATIONS CONTAINING DIVALENT AND TRIVALENT CATIONS SUCH AS VIDEX (DIDANOSINE) CHEWABLE/BUFFERED TABLETS OR THE PEDIATRIC POWDER FOR ORAL SOLUTION, MAY SUBSTANTIALLY INTERFERE WITH THE ABSORPTION OF QUINOLONES, RESULTING IN SYSTEMIC CONCENTRATIONS CONSIDERABLY LOWER THAN DESIRED.
GREPAFLOXACIN, LIKE OTHER QUINOLONES, MAY INHIBIT THE METABOLISM OF CAFFEINE AND THEOBROMINE & AND ENHANCED EFFECTS OF CAFFEINE AND THEOBROMINE. GREPAFLOXACIN IS A COMPETITIVE INHIBITOR OF THE METABOLISM OF THEOPHYLLINE. SERUM THEOPHYLLINE CONCENTRATIONS INCREASE; DOSE SHOULD BE HALVED.
CYCLOSPORINE. OTHER DRUGS METABOLIZED BY C.P.A. INCLUDE TERFENADINE, ASTEMIZOLE, CISAPRIDE, MIDAZOLAM, AND TRIAZOLAM. THE CONCOMITANT ADMINISTRATION OF A NONSTEROIDAL ANTI INFLAMMATORY DRUG WITH A QUINOLONE MAY INCREASE THE RISKS OF CNS STIMULATION AND CONVULSIONS. DISTURBANCES OF BLOOD GLUCOSE, INCLUDING HYPERGLYCEMIA AND HYPOGLYCEMIA, HAVE BEEN REPORTED IN PATIENTS TREATED CONCOMITANTLY WITH QUINOLONES AND AN ANTIDIABETIC AGENT. NO EFFECTS OF COUMARIN OR WARFARIN ON GREPAFLOXACIN. AVOID CONCOMITANT TREATMENT WITH MEDICATIONS KNOWN TO PROLONG THE QTC INTERVAL, E.G., CLASS I ANTIARRHYTHMIC AGENTS (E.G., QUINIDINE, PROCAINAMIDE), CLASS III ANTIARRHYTHMIC AGENTS (E.G., AMIODARONE, SOTALOL), AND BEPRIDIL, AS WELL AS ERYTHROMYCIN, TERFENADINE, ASTEMIZOLE, CISAPRIDE, PENTAMIDINE, TRICYCLIC ANTIDEPRESSANTS, AND SOME ANTIPSYCHOTICS, INCLUDING PHENOTHIAZINES, WHEN APPROPRIATE CARDIAC MONITORING CANNOT BE ASSURED, E.G., DURING OUTPATIENT THERAPY.