Drug Interaction Report

GENERALLY AVOID: Antibiotics may interfere with the therapeutic effects of oral fecal microbiota, which contains live bacterial spores. The mechanism may be related to the antibiotic inactivating the bacterial spores or reducing bacterial replication. However, the clinical significance of this interaction has not been established.

MANAGEMENT: Concomitant use of oral fecal microbiota spores with antibiotics should generally be avoided. The manufacturer of the oral formulation of fecal microbiota recommends that treatment commence two to four days after completing antibiotic treatment for Clostridium difficile infection.

ADJUST DOSING INTERVAL: There are no data regarding the effects of concurrent administration of oral fecal microbiota spores with food.

MANAGEMENT: The manufacturer of the oral formulation of fecal microbiota recommends that patients should have no food or drink except for a small amount of water for at least 8 hours prior to the first dose of fecal microbiota spores. The second and third doses of fecal microbiota spores should be taken on an empty stomach prior to the first meal of the day.

Concurrent ingestion of calcium-fortified foods (i.e., cereal, orange juice) may alter the bioavailability of gatifloxacin. The mechanism is chelation of calcium and the quinolone, resulting in decreased bioavailability. In the case of orange juice, inhibition of intestinal transport mechanisms (P-glycoprotein or organic anion-transporting polypeptides) by flavones may also be involved. Data have been conflicting: One study has reported no effect with milk coadministration. Another study reported a modest decrease in gatifloxacin bioavailability (13.5% decrease in Cmax,12% decrease in AUC, 15% increase in total clearance) when taken with 12 ounces of calcium-fortified orange juice instead of water, which could be clinically significant if the infecting organisms have borderline susceptibilities. The manufacturer states that gatifloxacin may be taken without regard to food, milk, or calcium. Clinicians should be aware of the possibility of an interaction if subtherapeutic effects are observed.