Antacids (aluminum- or magnesium-containing)
Concomitant administration of 300-mg cefdinir capsules with 30 mL Maalox® TC
suspension reduces the rate (Cmax) and extent (AUC) of absorption by approximately 40%. Time to reach
Cmax is also prolonged by 1 hour. There are no significant effects on cefdinir pharmacokinetics if the
antacid is administered 2 hours before or 2 hours after cefdinir. If antacids are required during OMNICEF therapy,
OMNICEF should be taken at least 2 hours before or after the antacid.
As with other b-lactam antibiotics, probenecid inhibits the renal excretion of cefdinir, resulting in an approximate doubling
in A.C. a 54% increase in peak cefdinir plasma levels, and a 50% prolongation in the apparent elimination
Iron Supplements and Foods Fortified With Iron
Concomitant administration of cefdinir with a therapeutic iron supplement containing 60 mg of
elemental iron (as FeSO4) or vitamins supplemented with 10 mg of elemental iron reduced extent of
absorption by 80% and 31%, respectively. If iron supplements are required during OMNICEF therapy, OMNICEF should be
taken at least 2 hours before or after the supplement.
The effect of foods highly fortified with elemental iron (primarily iron-fortified breakfast cereals)
on cefdinir absorption has not been studied.
Concomitantly administered iron-fortified infant formula (2.2 mg elemental iron/6 oz) has no
significant effect on cefdinir pharmacokinetics. Therefore, OMNICEF for Oral Suspension can be administered with
iron-fortified infant formula.
There have been rare reports of reddish stools in patients who have received cefdinir in Japan. The
reddish color is due to the formation of a nonabsorbable complex between cefdinir or its breakdown products and iron
in the gastrointestinal tract.
Drug/Laboratory Test Interactions
A false-positive reaction for ketones in the urine may occur with tests using nitroprusside, but not
with those using nitroferricyanide. The administration of cefdinir may result in a false-positive reaction for
glucose in urine using Clinitest®, Benedictís solution, or Fehlings solution. It is
recommended that glucose tests based on enzymatic glucose oxidase reactions (such as Clinistix® or
Tes-Tape®) be used. Cephalosporins are known to occasionally induce a positive direct Coombsí