%0 Journal Article
%A Ruiz-Caro, Roberto
%A Veiga, María D.
%T In vitro evaluation of acyclovir/chitosan floating systems
%D 2010
%@ 1996-1944
%U https://hdl.handle.net/20.500.14352/43337
%X Chitosan (CS) floating lyophilized formulations (L) for gastric drug delivery of acyclovir (ACV) have been developed. The freeze-dried formulations were obtained fromacidic aqueous suspensions prepared with different ACV/CS ratios. No changes in ACV crystallinity were observed during X-ray diffraction powder studies as a consequence of the manufacturing process. Considering that fed and fasted states modified the intragastric pH, swelling and in vitro dissolution studies were carried out in different acidic media (0.1 M HCl and progressive pH medium) in order to understand the influence of these physiological states on ACV/CS formulations. Swelling behavior of the floatinglyophilized formulations was dependent on CS and ACV proportions within L and on medium nature due to pH dependent CS solubility. Furthermore, no interactions between ACV and CS were detected in solid state according to the X-ray studies. In vitro dissolution of ACV from L was influenced by the swelling behavior. However, it isfeasible to optimize the ACV/CS ratios to achieve a desired formulation that releases the total quantity of ACV at a specific time. Moreover, floatability was assessed by buoyancy tests. The results demonstrated that the freeze-drying process achieved effective floating systems capable of remaining within the stomach while the total amount of ACV is released from L.
%~