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Краткое сообщение DESCRIPTION OF THE KINETICS OF RELEASE OF AMIKACIN FROM THE POLYMER MATRIX
© A. S. Shurshina*, A. R. Galina, M. A. Elinson, E. I. Kulish
Bashkir State University 32 Zaki Validi St., 450076 Ufa, Republic of Bashkortostan, Russia.
*Email: anzhela_murzagil@mail. ru Film systems on the basis of a chitosan of various molecular weight (334000 Da and 113000 Da) and an antibiotic amikacin are investigated. The equation of Ritger-Peppas, describing kinetics of medicine release is analyzed. It is shown that the release of amikacin from films of acetate of a chitosan in the conditions of insoluble matrix is described more correctly by used equation.
Keywords: diffusion, polymer film, kinetics.
Introduction
At present the attention of researchers is devoted to the study of polymer systems for controlled release of medicinal substance (MS). For the description of kinetics of release of MS from polymeric systems there is a set of models. Among them it is possible to note the equation of Ritger and Peppas [1] which can be used for the characteristic of release of medicine both from swelling up, and from not swelling up polymeric matrixes.
Analysis of the kinetics release of MS from the chitosan films in the conditions of interface of processes of diffusion and dissolution of a polymeric matrix became the purpose of this work.
Experimental
We used the sample of a chitosan (ChT) of production of Bioprogress (Russia) received by an alkaline deacetyla-tion of crab chitin (deacetylation degree ~ 84%) with Md=113000 and 334000. As the medicinal substance (MS) an antibiotic amikacin (AM) was used.
Film samples were prepared similarly [2]. The content of MS in a film was 0.1 mol/mol of ChT.
Release of MS from polymer matrix was studied according to the methodology in [2]. The kinetics of release of MS was described, using Ritger - Peppas's equation:
Gs/r =Ktm (1),
where Gs is quantity of MS released from a polymeric matrix by the time of t; is equilibrium quantity of the released MS; K is the kinetic constant characterizing the rate of release of MS from a polymeric matrix; M is the exponential parameter connected with the mechanism of release of MS.
Results and discussion
The films received from a high-molecular sample of ChT (Md = 334000 Da) were dissolved in water rather slowly and during the experiment they changed the initial weight no more than to 3-5%. At immersion in water chi-tosan films formed from samples of chitosan with Msd = 113000 Da, they lose weight quickly enough, owing to dissolution.
Distinction in solubility of films of different samples of ChT finds the reflection in kinetics of release of MS from films. In the case of insoluble matrix, it is possible to speak about the prolonged release of MS from a film, in the case
of soluble, - no, as all MS completely releases during the time comparable to time of dissolution of a film. According to it, application by the equation of Ritger - Peppas for the description of kinetic regularities of release of AM in case of an insoluble and soluble polymeric matrix give various results (tab. 1).
Table 1
Value of kinetic parameters of process of release of medicinal substance - amikacin from the chitosan films received with the use of the equation of Ritger and Peppas
Msd ChT
Time of annealing, min К, min 1 Coefficient of correlation
0 0.045 0.98
30 0.041 0.98
60 0.040 0.99
120 0.039 0.99
0 0.021 0.93
30 0.062 0.93
60 0.028 0.94
120 0.070 0.95
334000
113000
From data of the table it is visible that the correlation coefficient in case of use of the dissolved ChT samples with Md = 113000 Da is less, than when using ChT with Msd = 334000 Da, almost not dissolved during the experiment. But it's not in numerical values of coefficient of correlation, and in that Ritger-Peppas's equation accurately reflects the regularities which are observed in experimental conditions only for ChT with Msd = 334000 Da. In this case the values of kinetic constants K determined by the equation (1) for the films subjected to isothermal annealing accurately reflect the regularities observed in the experiment, namely - the increase in the time of isothermal annealing which, is followed by the decrease of solubility of a polymeric matrix in water, lead to the decrease of the rate of release of MS. When using ChT with Msd = 113000 Da Ritger-Peppas's equation practically does not work.
Thus, the equation of Ritger-Peppas works correctly only in the case of the insoluble matrix.
REFERENCES
1. Ritger P. L., Peppas N. A. A simple equation for description of solute release. I. Fickian and Non-Fickian release from non-swellable devices in the form of slabs, spheres, cylinders or discs // J. Control. Release. 1987. Vol. 5. Pp. 23-26.
2. Kulish E. I., Shurshina A. S., Kolesov S. V. Specific transport properties of medicinal chitosan films // Polymer science, Ser. A. 2014. Vol. 56. №3. Pp. 289-295.
Received 14.11.2015.
