A. S. Shurshina

Transport properties of Chitosan-Amikacin films

The transport properties of films based on chitosan and a drug have been studied, and sorption and diffusion characteristics of the films have been examined. The calculated diffusion coefficients and the abnormal kinetic curves of amikacin release have been discussed. An analysis of the obtained data showed that the process of drug transport from chitosan films deviated from the classical Fick’s laws due to structural changes in the polymer matrix induced by its chemical modification because of interaction with the drug.

Specific transport properties of medicinal chitosan films

Processes of water-vapor sorption by medicinal chitosan films and the kinetics of release of antibiotics of the cephalosporin series from these films have been studied. It has been found that the structural changes in the polymer matrix that are related particularly to its chemical modification via the interaction with drugs are the most probable cause of the deviation of the mass-transfer mechanism from the classical Fick’s mechanism.

A rheological study of molecular and supramolecular organization of chitosan succinamide in a mixed water–etanol solvent

An approach based on quality reduction of the solvent, namely, the use of mixed water–ethanol solvents of variable volume ratio was used for control over the aggregation and formation of a physical net of bonds in chitosan succinamide solutions. A study of the molecular and supramolecular organization of chitosan succinamide in solution showed that this polymer, which does not aggregate in a dilute (to the crossover point) aqueous solution, aggregates in a mixed water–ethanol solvent even at high dilution. Polymer structurization in solution is accompanied by the formation of an additional net of physical bonds, whose nodes are aggregates of chitosan succinamide macromolecules formed in the mixed solvent. It leads to earlier formation of viscoelastic properties, which is ultimately reflected by the regularities of some physicochemical properties of materials formed from solution.

The role of low-molecular-mass electrolyte drug substances in the modification of the chitosan matrix

The effect of antibiotics of the aminoglycoside and cephalosporin series on the properties of chitosan films formed from acetic acid solutions is studied. It is shown that the introduction of the indicated substances substantially affects the conformational state of chitosan acetate and its supramolecular structure. The modification of chitosan by drug substances, accompanied by loss in solubility of chitosan films in water, leads to a decrease in the rate of desorption of antibiotics from the polymer matrix.

Preparation of Enzyme-Containing Chitosan Films

The preparation and modification of enzyme-containing chitosan films were studied. Some features of the interaction of chitosan with proteolytic enzymes - trypsin, collagenase, and pepsin - were studied. Conditions were selected for the modification of enzyme-containing chitosan films. These films may be suitable for the treatment of purulent and necrotic wounds.

Supramolecular Conformational Effect in Complexations of Pectin and Chitosan Polysaccharides with Some Cephalosporin and Aminoglycoside Antibiotics

The reactions of the polysaccharides pectin (Pc) and chitosan (CTS) with antibiotics of cephalosporin and aminoglycoside series were studied. The complexation between the drugs and polymers was found to occur via hydrogen bonding. Dilution of the chitosan polycation increased the probability of occurrence of the negative ions of the cephalosporin antibiotic near the chain and lowered the probability of occurrence of the positive ions of aminoglycoside antibiotics, which affected the amount of adducts. When the pectin polyanion was diluted, the opposite situation was observed.

Enzymatic Decomposition of Chitosan-Based Film Materials Modified by Antibiotics of the Cephalosporin Series

The enzymatic decomposition of film materials based on chitosan with inclusions of cephalosporin antibiotics on a substrate impregnated with Ringer–Locke’s solution was studied. The introduction of antibiotics led to a decrease in the rate of the enzymatic decomposition of chitosan, as in the case of chitosan lysis in the presence of aminoglycoside antibiotics. A possible reason for the decrease in the rate of the enzymatic decomposition of chitosan is suppression of polyelectrolyte swelling in the presence of low-molecular electrolytes including medicinal agents. The introduction of drugs in the chitosan-based film is a potential method for selectively decreasing the rate of enzymatic hydrolysis of chitosan for increasing the service life of the film material on a wound surface.

Behavior of a Chitosan–Drug System during Diffusion Processes

The process of water vapor sorption by medical chitosan films and the release of nonelectrolyte drugs from these films are investigated. It is shown that the nonelectrolyte drugs are unable to modify the chitosan matrix and cannot provide a prolonged drug release. The modification of chitosan–drug films, for example, by isothermal annealing or transition from the salt form of chitosan to the base one, is required to decelerate the release of drugs from the films.

Kinetics of the release of a drug from a soluble or hydrolyzable polymer matrix

Film systems based on chitosan with different molecular weights (334 000 and 113000 Da) and amikacin, an aminoglycoside series antibiotic, are studied. The Ritger–Peppas, Hixson–Crowell, and Hopfenberg equations for describing the kinetics of drug release are tested. It is demonstrated that the release of amikacin from chitosan acetate films under conditions of concurrent diffusion and dissolution (hydrolysis) of the polymer matrix are more closely described by the Hopfenberg equation. It has been established that the isothermal annealing of the film causes a decrease in the kinetic constants characterizing the rate of drug release from the polymer matrix.

Creating Chitosan-Based Prolonged-Release Film Coatings

The interaction of chitosan with cephalosporin (cefazolin and cefotaxime) and aminoglycoside (amikacin and gentamicin) antibiotics was investigated. It was established that the medicinal preparation could be distributed in the polymer matrix in two ways during formation of the film coating. Apart of it was bound rather strongly to the polymer chain, e.g., via complexation. Another part of it was concentrated in the polymer free space (in polymer pores). Astudy of antibiotic release from chitosan film coatings showed that the release rate from the film was determined on one hand by the amount of antibiotic complexed to chitosan and, on the other, to the condition of the polymer matrix. These films could be suitable for treatment of surgical wounds, burns, and slow-healing wounds of various etiology.