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. 2010 Dec 6;3(12):5195-5211.
doi: 10.3390/ma3125195.

In vitro Evaluation of Acyclovir/Chitosan Floating Systems

Roberto Ruiz-Caro  1 , María D Veiga  2   3
Affiliations

In vitro Evaluation of Acyclovir/Chitosan Floating Systems

Roberto Ruiz-Caro et al. Materials (Basel). .

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; controlled release; floating freeze-dried formulations; swelling behavior.

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Figures

Figure 1
Figure 1
X-Ray powder diffraction patterns of ACV (a); CS (b); and systems L1 (0.5:1 w/w ACV:CS) (c); L2 (0.5:2 w/w ACV:CS) (d); L3 (0.5:3 w/w ACV:CS) (e); L4 (0.5:4 w/w ACV:CS) (f); L5 (0.5:5 w/w ACV:CS) (g); L6 (2:1 w/w ACV:CS) (h); L7 (2:2 w/w ACV:CS) (i); L8 (2:3 w/w ACV:CS) (j); L9 (2:4 w/w ACV:CS) (k); and L10 (2:5 w/w ACV:CS) (l); in solid state.
Figure 2
Figure 2
Swelling ratio of freeze-dried systems B1 (1% CS), B2 (2% CS), B3 (3% CS), B4 (4% CS), B5 (5% CS), L1 (0.5:1 w/w ACV:CS), L2 (0.5:2 w/w ACV:CS), L3 (0.5:3 w/w ACV:CS), L4 (0.5:4 w/w ACV:CS), L5 (0.5:5 w/w ACV:CS), L6 (2:1 w/w ACV:CS), L7 (2:2 w/w ACV:CS), L8 (2:3 w/w ACV:CS), L9 (2:4 w/w ACV:CS) and L10 (2:5 w/w ACV:CS) in 0.1 M HCl medium (pH 1) (A) and in progressive pH medium (pH 1.5 formula image pH 4) (B).
Figure 3
Figure 3
Evolution of freeze-dried formulations (F) B1 (1% CS), B2 (2% CS), B3 (3% CS), B4 (4% CS), B5 (5% CS), L1 (0.5:1 w/w ACV:CS), L2 (0.5:2 w/w ACV:CS), L3 (0.5:3 w/w ACV:CS), L4 (0.5:4 w/w ACV:CS), L5 (0.5:5 w/w ACV:CS), L6 (2:1 w/w ACV:CS), L7 (2:2 w/w ACV:CS), L8 (2:3 w/w ACV:CS), L9 (2:4 w/w ACV:CS) and L10 (2:5 w/w ACV:CS) for swelling study in 0.1 M HCl medium (pH 1).
Figure 4
Figure 4
Evolution of freeze-dried formulations (F) B1 (1% CS), B2 (2% CS), B3 (3% CS), B4 (4% CS), B5 (5% CS), L1 (0.5:1 w/w ACV:CS), L2 (0.5:2 w/w ACV:CS), L3 (0.5:3 w/w ACV:CS), L4 (0.5:4 w/w ACV:CS), L5 (0.5:5 w/w ACV:CS), L6 (2:1 w/w ACV:CS), L7 (2:2 w/w ACV:CS), L8 (2:3 w/w ACV:CS), L9 (2:4 w/w ACV:CS) and L10 (2:5 w/w ACV:CS) for swelling study, in progressive pH medium (pH 1.5 formula image pH 4).
Figure 5
Figure 5
Dissolution profiles of freeze-dried systems (L) L1 (0.5:1 w/w ACV:CS), L2 (0.5:2 w/w ACV:CS), L3 (0.5:3 w/w ACV:CS), L4 (0.5:4 w/w ACV:CS), L5 (0.5:5 w/w ACV:CS), L6 (2:1 w/w ACV:CS), L7 (2:2 w/w ACV:CS), L8 (2:3 w/w ACV:CS), L9 (2:4 w/w ACV:CS) and L10 (2:5 w/w ACV:CS) in 0.1 M HCl medium (pH 1) (A) and in progressive pH medium (pH 1.5 formula image pH 4) (B).
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