Physical and Chemical Stability of Buffered Articaine: An In-Vitro Study

Objective: There is a lack of scientific data on the shelf-life of buffered articaine solutions. This study evaluated the physical and chemical stability of buffered 4% articaine with 1:100,000 epinephrine. Materials and Methods: For the study of physical stability, two groups (1P, 2P) (“P” designating samples to study physical stability) of triplet samples were prepared. The 1P samples were stored at 8 °C, and the 2P samples were stored at 25°C. The samples were evaluated every hour till 8 hours by inspecting the appearance of particulate matter against a black background, color change against a white background and pH using a calibrated pH meter. For the study of chemical stability, 4 groups (1C, 2C, 3C and 4C) (“C” designating samples to study chemical stability ) of triplet samples were prepared. 1C and 2C were used to evaluate the stability of articaine stored at 8°C and 25°C. 3C and 4C were used to evaluate the stability of epinephrine stored at 8°C and 25°C,respectively. The samples were evaluated every hour till 8 hours using a validated high-performance liquid chromatography method. Independent tests were applied for statistical analysis. Results : All the test samples remained colorless and clear for a period of 8 hours. The pH significantly increased from baseline at both 8°C and 25°C every hour until8 hours but remained within the acceptable physiological pH. There was no significant degradation in the concentration of buffered articaineafter 8 hours at either 25°C or 8°C. However, the concentration of epinephrine significantly decreased at every test interval after 1 hour at 25°C ( p = 0.002)and after 2 hours at 8°C ( p = 0.038). Conclusion : The buffered articaine solution remained physically stable at 8 hours. The buffered articaine solution remained chemically stable at 8 hours at 8°C and 25°C. Epinephrine remained chemically stable for 2 hours at 8°C and 1 hour at 25°C.