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

Abstract

Aim. To study the rheological parameters of medicinal and cosmetic products that are available in the Ukrainian
pharmaceutical market in the form of a gel for the treatment of dermatological diseases (acne) in order to determine
the acceptability criteria when assessing the rheological properties of gels.
Materials and methods. The study objects were medicines containing retinoids (adapalene and tretinoin) and a
cosmetic 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, which
makes it difficult to assess the values obtained and determine compliance. Therefore, due to the lack of universal
criteria for assessing rheological parameters and the necessity to determine acceptable rheological property ranges
in the development of soft dosage forms containing retinoids, it became essential to establish acceptable rheological
parameter ranges on the example of existing gel forms for treating acne. Analyzing the shear stress range values, in
which the flow curves are located, it can be determined that acceptable ranges for the new drug being developed are
the shear stress range of 25–100 Pa under similar or approximate experimental conditions. The initial viscosity of the
gels studied ranges from 30 to 100 Pa·s.
Conclusions. The experimental studies have demonstrated that the gels presented in the study exhibit high
thixotropic properties, indicating significant structural recovery after mechanical deformation caused by the measuring
system inner cylinder. The acceptable shear stress range for the new drug being developed should be within 25–100 Pa under
similar 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 new
pharmaceutical product for the treatment of dermatological diseases