The structural-mechanical studies of the gel with hyaluronic acid and decametoxin
Authors: Melnyk G. M. , Yarnykh T. G. , Buryak M. V. 
Published: July 2021

According to domestic and foreign literature, patients with the surgical profile with infected wounds and purulent-inflammatory complications make up the majority of patients. For the treatment of chronic wounds and bedsores together with the inhibition of the growth of microorganisms, a drug must provide the optimal conditions for the growth of granulation, and have the reparative and anti-inflammatory effect. One of the main modern principles of wound healing is the pathogenetic orientation according to the phase of the wound process. Therefore, one of the current problems of modern pharmacy is the development of drugs for the treatment of infected wounds and bedsores with the complex pharmacological activity.
Aim. To experimentally substantiate the technological mode for production of an extemporaneous gel with decamethoxine and hyaluronic acid.
Materials and methods. The gel was prepared at a temperature of 15-25 °C. The gel base was prepared according to the conventional technology. Due to the fact that the polymer was already pre-neutralized with ammonia, Aristoflex AVC (“Clariant Surfactants”, Switzerland) weighed in portions was added in the calculated amount of water and stirred at a slow speed of the agitator of 60-70 rpm (to prevent air bubbles) to form a gel, then gradually added the weighed glycerol, and aqueous solutions of active pharmaceutical ingredients (API) previously prepared. The plastically viscoelastic properties of the gel developed were studied on a BROOKFIELD DV-II + PRO viscometer.
Results. During the analysis of the dependence of viscosity on the shear rate obtained it was found that the rheological behavior of the gel studied was characterized by an inverse decrease in viscosity with increasing the shear rate, i.e. there was a pseudo-plastic type of flow characteristic of coagulation-thixotropic structures, under the influence of an increasing mechanical load on which the structural associates were destroyed. The ascending and descending curves formed “hysteresis loops”, indicating the thixotropy of the systems capable of recovery after destruction. Thus, we can assume that the resulting gel has stable plastic properties, easy to apply and distribute on the surface. It was found that the value of the mechanical stability (MS) of the gel was 1.1, and its base – 1.2. It, in turn, confirms the thixotropic properties that allow restoring the structures after stress, which occurs in the technological process of soft dosage forms.
Conclusions. The study of the dependence of the structural viscosity on the shear rate gradient for the gel developed and the gel base at different temperature values (20, 34 °C) has demonstrated that the viscosity of the compositions decreases with increasing the shear rate gradient, providing the necessary process parameters (accuracy and ease of dosing) and such consumer characteristics as the optimal spreading when using the drug. It has been found that the MS value of the gel confirms its thixotropic properties, which allow restoration of the structures after the applied stresses that occur during the technological process.