Abstract
The article presents the results of the development of topical gel formulations based on plant extracts derived from the roots and the above-ground parts of Limonium gmelinii, in accordance with the ICH Q8 (R2) “Pharmaceutical development” guideline. The study evaluated the compatibility of plant extracts with excipients and optimized their content in the gel formulations. Carbomer was used as the gelling agent, while propylene glycol (PG), glycerin, and PEG-400 were applied as co-solvents and penetration enhancers. Various concentrations of carbomer and PG were tested to determine the most optimal gel compositions. The optimal formulations were selected based on organoleptic characteristics, colloidal and thermal stability, rheological properties, and the release kinetics of plant extracts. Gels containing 1.0% carbomer demonstrated optimal viscosity and thixotropic behavior, ensuring ease of application and product stability. The use of 10.0% PG resulted in a cumulative release of 87.36% for the above-ground parts extracts and 85.78% for the root extracts in in vitro tests. Long-term stability of the gels was confirmed over 12 months of storage. These results suggest that the developed gels have significant potential for further pharmaceutical development and may have therapeutic applications in treating various diseases.