Cranberry juice consumption is often recommended along with low-dose oral antibiotics for prophylaxis for
recurrent urinary tract infection (UTI). Because multiple membrane transporters are involved in the intestinal
absorption and renal excretion of -lactam antibiotics, we evaluated the potential risk of pharmacokinetic
interactions between cranberry juice and the -lactams amoxicillin (amoxicilline) and cefaclor. The amoxicillin-
cranberry juice interaction was investigated in 18 healthy women who received on four separate occasions
a single oral test dose of amoxicillin at 500 mg and 2 g with or without cranberry juice cocktail (8 oz) according
to a crossover design. A parallel cefaclor-cranberry juice interaction study was also conducted in which 500 mg
cefaclor was administered with or without cranberry juice cocktail (12 oz). Data were analyzed by noncompartmental
methods and nonlinear mixed-effects compartmental modeling. We conclude that the concurrent
use of cranberry juice has no significant effect on the extent of oral absorption or the renal clearance of
amoxicillin and cefaclor. However, delays in the absorption of amoxicillin and cefaclor were observed. These
results suggest that the use of cranberry juice at usual quantities as prophylaxis for UTI is not likely to alter
the pharmacokinetics of these two oral antibiotics.