RESUMEN
The aim of this work was to increase the bioavailability of riboflavin through the preparation of sustained release floating capsules using factorial design 23 technique. Seven floating capsules were prepared from granulated mixture of the drug with sodium bicarbonate, as CO2 generating agent, and one or more of three different polymers; namely, Eudragit L100, hydroxypropyl methyl cellulose [HPMC] and sodium alginate [according to a matrix table]. The effect of different polymers and their combinations on the in vitro release profile of the prepared floating riboflavin capsules was studied. Both capsules prepared with HPMC or mixture of HPMC and Eudragit L100 gave better drug release patterns. The mixed polymer formula [riboflavin/HPMC-Eudragit L100] was chosen for the in vivo evaluation in comparison with a control capsule using fluorimetric HPLC method for riboflavin analysis in the urine of five healthy volunteers. The initial excretion rates for the prepared floating formula were much higher than those of the conventional formula. The relative bioavailability of the prepared floating formula was 121% of the conventional formula, which indicated the superiority of the prepared floating capsule