Determination of rheological parameters of gels used in the treatment of dermatological skin diseases

Aim. To study the rheological parameters of medicinal and cosmetic products that are available in the Ukrainianpharmaceutical market in the form of a gel for the treatment of dermatological diseases (acne) in order to determinethe acceptability criteria when assessing the rheological properties of gels.Materials and methods. The study objects were medicines containing retinoids (adapalene and tretinoin) and acosmetic product (a therapeutic and preventive gel). The rheological properties of the gel samples were assessed using a Rheolab QC rotational rheometer (Anton Paar) equipped with a C-CC27 / SS coaxial cylinder system.Results. The results of rheological studies depend on the experimental conditions and the equipment used.The challenge in assessing rheological properties lies in the absence of specific values for soft dosage forms, whichmakes it difficult to assess the values obtained and determine compliance. Therefore, due to the lack of universalcriteria for assessing rheological parameters and the necessity to determine acceptable rheological property rangesin the development of soft dosage forms containing retinoids, it became essential to establish acceptable rheologicalparameter ranges on the example of existing gel forms for treating acne. Analyzing the shear stress range values, inwhich the flow curves are located, it can be determined that acceptable ranges for the new drug being developed arethe shear stress range of 25–100 Pa under similar or approximate experimental conditions. The initial viscosity of thegels studied ranges from 30 to 100 Pa·s.Conclusions. The experimental studies have demonstrated that the gels presented in the study exhibit highthixotropic properties, indicating significant structural recovery after mechanical deformation caused by the measuringsystem inner cylinder. The acceptable shear stress range for the new drug being developed should be within 25–100 Pa undersimilar or approximate experimental conditions. The gels have been identified as pseudoplastic dispersed systems.As the initial viscosity of the gels studied ranges from 30 to 100 Pa·s, it must be considered when developing a newpharmaceutical product for the treatment of dermatological diseases