** Levofloxacin is ineffective if given with multi-valent cation containing products e.g. antacids, supplements or feeds containing calcium, iron, magnesium, zinc, sucralfate or bismuth. These products bind to doxycycline and reduce its absorption by up to 90%.
If patients are prescribed antacids or supplements containing calcium iron, magnesium zinc or bismuth. It is advised these medications are stopped/withheld for the duration of antibiotic treatment. If this is not possible due to a clinical need, then an alternative antibiotic must be considered
If doxycycline/ciprofloxacin and a cation containing product must be prescribed together:
· Administration times should be as far apart as possible
· Reduce the dosing frequency of the interacting product if possible
· In the case of oral nutritional supplements, multiple sips throughout the day should be replaced with set administration times to enable adequate spacing from oral antibiotic administration
· If a patient is receiving an enteral feed doxycycline should generally be avoided unless there is a specific feed free window