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Materials 2010, 3(12), 5195-5211; doi:10.3390/ma3125195
Article

In vitro Evaluation of Acyclovir/Chitosan Floating Systems

1
 and
1,2,*
1 Departamento de Farmacia y Tecnología Farmacéutica, Facultad de Farmacia, Universidad Complutense de Madrid, Plaza Ramón y Cajal s/n, 28040-Madrid, Spain 2 Unidad de Biotransformaciones Industriales, Parque Científico de Madrid PTM, 28760-Tres Cantos, Madrid, Spain
* Author to whom correspondence should be addressed.
Received: 27 October 2010 / Revised: 24 November 2010 / Accepted: 25 November 2010 / Published: 6 December 2010
(This article belongs to the Special Issue Chitins)
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Abstract

Chitosan (CS) floating lyophilized formulations (L) for gastric drug delivery of acyclovir (ACV) have been developed. The freeze-dried formulations were obtained from acidic 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 floating lyophilized 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 is feasible 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.
Keywords: Acyclovir; chitosan; floating freeze-dried formulations; swelling behavior; controlled release Acyclovir; chitosan; floating freeze-dried formulations; swelling behavior; controlled release
This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).
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Ruiz-Caro, R.; Veiga, M.D. In vitro Evaluation of Acyclovir/Chitosan Floating Systems. Materials 2010, 3, 5195-5211.

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