Developement and Stability Evaluation of Natural Topical Formulations Containing Pinus sibirica Essential Oil

Pinus sibirica (P. sibirica) is used in folk medicine for centuries in treatment of various diseases due to its anti-inflammatory, antioxidant, and antimicrobial activity. The present study was focused on formulating semi-solid topical cream and gel preparations with P. sibirica essential oil (EOPS) and on evaluation of their stability during three months of storage. After preparation of semi-solid formulations (cream and gel), we followed parameters such as organoleptic characteristics, pH values, electrical conductivity, phase separation, washability, swelling index and microbiological contamination. Tests for physical and microbiological stability were performed considering different storage conditions at temperature (4±2° C, 25±2°C and 40±2°C) for 12 weeks. All test were performed at sampling time points of 7^th, 30^th, 60^th, 90^th day after storage. Cream with EOPS was white colour, it is homogenous with pleasant odor characteristic to used EOPS while gel with EOPS was transparent, it is homogenous with specific odor. After application to skin, EOPS cream was leaving non-greasy film while gel with EOPS was leaving sticky film and cooling effect. In all tested samples, we observed no phase separation and pH values were optimal for skin application. During three months of storage at different conditions, all tested formulations were stable and addition of EOPS did not cause any changes in followed parameters. Both cream and gel formulation remained stable since we did not notice any significant changes in all followed parameters during storage at different temperatures. Addition of 0.5% of EOPS did not change visual, sensory and microbial properties of formulations.