Drug Interaction Report

ADJUST DOSING INTERVAL: Oral preparations that contain magnesium, aluminum, or calcium may significantly decrease the gastrointestinal absorption of quinolone antibiotics. Absorption may also be reduced by sucralfate, which contains aluminum, as well as other polyvalent cations such as iron and zinc. The mechanism is chelation of quinolones by polyvalent cations, forming a complex that is poorly absorbed from the gastrointestinal tract. The bioavailability of ciprofloxacin has been reported to decrease by as much as 90% when administered with antacids containing aluminum or magnesium hydroxide.

MANAGEMENT: When coadministration cannot be avoided, quinolone antibiotics should be dosed either 2 to 4 hours before or 4 to 6 hours after polyvalent cation-containing products to minimize the potential for interaction. When coadministered with Suprep Bowel Prep (magnesium/potassium/sodium sulfates), the manufacturer recommends administering fluoroquinolone antibiotics at least 2 hours before and not less than 6 hours after Suprep Bowel Prep to avoid chelation with magnesium. Please consult individual product labeling for specific recommendations.

GENERALLY AVOID: Alcohol may potentiate some of the pharmacologic effects of CNS-active agents. Use in combination may result in additive central nervous system depression and/or impairment of judgment, thinking, and psychomotor skills.

MANAGEMENT: Patients receiving CNS-active agents should be warned of this interaction and advised to avoid or limit consumption of alcohol. Ambulatory patients should be counseled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.

GENERALLY AVOID: The concurrent use of aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs) and ethanol may lead to gastrointestinal (GI) blood loss. The mechanism may be due to a combined local effect as well as inhibition of prostaglandins leading to decreased integrity of the GI lining.

MANAGEMENT: Patients should be counseled on this potential interaction and advised to refrain from alcohol consumption while taking aspirin or NSAIDs.

GENERALLY AVOID: The oral bioavailability of quinolone and tetracycline antibiotics may be reduced by concurrent administration of preparations containing polyvalent cations such as aluminum, calcium, iron, magnesium, and zinc. Therapeutic failure may result. The proposed mechanism is chelation of quinolone and tetracycline antibiotics by di- and trivalent cations, forming an insoluble complex that is poorly absorbed from the gastrointestinal tract. Reduced gastrointestinal absorption of the cations should also be considered.

MANAGEMENT: Concomitant administration of oral quinolone and tetracycline antibiotics with preparations containing aluminum, calcium, iron, magnesium, and/or zinc salts should generally be avoided. Otherwise, the times of administration should be staggered by as much as possible to minimize the potential for interaction. Quinolones should typically be dosed either 2 to 4 hours before or 4 to 6 hours after polyvalent cation preparations, depending on the quinolone and formulation. Likewise, tetracyclines and polyvalent cation preparations should typically be administered 2 to 4 hours apart. The prescribing information for the antibiotic should be consulted for more specific dosing recommendations.