Stability of an Aspirin in the Aspirin+Curcumin Admixture at Different Storage Conditions

Aims: The pure stability of aspirin in the aspirin (100 μg/mL) only and aspirin (100 μg/mL) +curcumin (600 μg/mL) admixture without any ingredient under two solvents (distilled water, DW and normal saline, NS), three storage temperatures (25ºC, 4ºC and -20ºC) and periods (1st, 3rd and 7th days) was evaluated.
Study Design: The injectable DW- and NS-aspirin containing solutions in the laboratory cap polyethylene bottle were stored and evaluated at controlled temperature (25ºC, 4ºC and -20ºC) during 7 days.
Methodology: Effects of admixture compounds, periods of storage and temperature of storage on the concentrations of active compound (aspirin) were analyzed. The concentration of aspirin in each solution was determined by stability-indicating high-performance liquid chromatography (HPLC)-ultraviolet (UV) detection. A 1.0 mL volume of each sample was withdrawn and reconstituted with 3.0 mL of ethanol and directly injected into HPLC system immediately after filtration at 1st, 3rd and 7th days for analysis. The stability of the solutions was determined by calculating the percentage of the initial aspirin concentrations remaining at each test condition and periods. Stability was defined as the retention of at least 90% of the initial aspirin concentration.
Results: The concentration of aspirin of the aspirin only and aspirin+curcumin admixture solutions remained at least 90% of original without any color change or precipitation in the DW and NS solution at 4ºC and -20ºC throughout 7 day period and showed instability that decreased gradually below 90% of original concentrations after 1 day at 25ºC in the two solutions.
Conclusion: Two kinds of solutions of only aspirin and aspirin+curcumin admixture, in DW and NS, showed different stability dependence on temperature of storage that means maintained stability at 4ºC and -20ºC and did not show effect of admixture of curcumin on aspirin stability during 7 days except 25ºC.