Contraception, 2004, n. 70
To the beneficial properties of dietary fiber in human health, several disadvantages can be added as the possible modification of the
bioavailability of other drugs when administered by the oral route. In this study, the influence of glucomannan in the oral bioavailability of
ethinyl estradiol (EE), when administered to female rabbits in two different dosage forms (enteric capsules and dispersed in water), was
established. To carry out the study, three groups of six animals each were used. All animals received 1 mg kg 1 oral EE, and rabbits in groups
2 and 3 received 1.5 g glucomannan dispersed in water or in enteric capsules, respectively, immediately before EE. When comparing the
results obtained after the administration of EE/glucomannan dispersed in water with those obtained after the administration of this estrogen
without fiber, we can see that Cmax is 1.4 times lower, AUC 1.9 times lower and that tmax is identical (10 min). However, after the
administration of fiber in enteric capsules, AUC and Cmax are higher (4.1 and 7.8 times, respectively) than when the estrogen was
administered alone, and also, there is a delay in tmax (20 min). After the administration of glucomannan in the enteric capsule, the fiber forms,
as in the stomach, a highly viscous solution in the gut that would limit EE access to the mucosal surface delaying its absorption. However,
this effect could be compensated by a reduction of EE metabolism in the intestinal wall, leading to a higher absorption of the estrogen.
