For the following substances absence of a clinically relevant interaction with Moxifloxacin was proven: atenolol, ranitidine, calcium supplements, theophylline, oral contraceptives, glibenclamide, itraconazole, digoxin, morphine, probenecid.
No dosage adjustment is necessary for these drugs.
Antacids, minerals and multi-vitamins: Concomitant ingestion of Moxifloxacin together with antacids, minerals and multi-vitamins may result in impaired absorption of moxifloxacin after oral administration due to formation of chelate complexes with the multivalent cations contained in these preparations. This may lead to plasma concentrations considerably lower than desired. Hence, antacids, antiretroviral drugs (e.g. didanosine) and other preparations containing magnesium or aluminium, sucralfate and agents containing iron or zinc should be administered at least 4 hours before or 2 hours after ingestion of an oral moxifloxacin dose.
Ranitidine: The concomitant administration with ranitidine did not change the absorption characteristics of moxifloxacin. Absorption parameters (Cmax, Tmax, AUC) were comparable indicating absence of an influence of gastric pH on moxifloxacin uptake from the GI-tract.
Calcium supplements: When given with high dose calcium supplements only a slightly reduced rate of absorption was observed while extent of absorption remained unaffected. The effect of high dose calcium supplements on the absorption of moxifloxacin is considered as clinically not relevant.
Theophylline: In accordance with in vitro data no influence of moxifloxacin on theophylline pharmacokinetics and vice versa at steady state was detected in humans, indicating that moxifloxacin does not interfere with the 1A2 subtypes of the cytochrome P450 enzymes.
Warfarin: No interaction during concomitant treatment with warfarin on pharmacokinetics, prothrombin time and other coagulation parameters have been observed.
Changes in INR (International Normalized Ratio): Cases of increased anticoagulant activity have been reported in patients receiving anticoagulants concurrently with antibiotics, including moxifloxacin. The infectious disease (and its accompanying inflammatory process), age and general status of the patient are risk factors. Although an interaction between moxifloxacin and warfarin was not demonstrated in clinical trials, INR monitoring should be performed and, if necessary, the oral anticoagulant dosage should be adjusted as appropriate.
Oral contraceptives: No interaction has occurred following concomitant oral administration of moxifloxacin with oral contraceptives.
Antidiabetics: No clinically relevant interaction was seen between glibenclamide and moxifloxacin.
Itraconazole: Exposure (AUC) to itraconazole was only marginally altered under concomitant moxifloxacin treatment. Pharmacokinetics of moxifloxacin was not significantly altered by itraconazole. No dosage adjustment is necessary for itraconazole when given with moxifloxacin and vice versa.
Digoxin: The pharmacokinetics of digoxin is not significantly influenced by moxifloxacin and vice versa. After repeated dosing in healthy volunteers, moxifloxacin increased Cmax of digoxin by approximately 30% at steady state without affecting AUC or through levels.
Morphine: Parenteral administration of morphine with moxifloxacin did not reduce the oral bioavailability of moxifloxacin and only slightly decreased Cmax (17 %).
Atenolol: The pharmacokinetics of atenolol is not significantly altered by moxifloxacin. Following single dose administration in healthy subjects AUC was marginally increased (by approximately 4%) and peak concentrations were decreased by 10%.
Probenecid: No significant effect on apparent total body clearance and renal clearance of moxifloxacin was found in a clinical study investigating the impact of probenecid on renal excretion.
Charcoal: Concomitant dosing of charcoal and 400 mg oral moxifloxacin reduced the systemic availability of the drug by more than 80% by preventing absorption in vivo. The application of activated charcoal in the early absorption phase prevents further increase of systemic exposure in cases of overdose. After intravenous drug administration carbo medicinal is only slightly reduces systemic exposure (by approximately 20%).
Food and dairy products: Absorption of moxifloxacin was not altered by food intake (including dairy products). Moxifloxacin can be taken independent from food intake.