Abstract
In this study, a sensitive quantitative method based on high performance liquid chromatography combined with high-resolution mass spectrometry, Q ExactiveTM-Orbitrap® was set up and applied for the determination of the immunosuppressor agents cyclosporine A and tacrolimus in novel ethanol-free ophthalmic formulations for the treatment of Vernal keratoconjunctivitis. Different storage parameters in terms of storage temperatures and practical usage conditions were investigated to assess the stability of all formulations during shelf life simulating the real conditions as well to confirm the feasibility of use of ethanol-free products. The methodology was linear (r2 = 0.995) over the concentration range 0-200 ng/mL, and its selectivity, precision, accuracy and recovery were all within the required limits. Under different conditions (storage period 0-90 days, 5-25 °C, unopened/usage simulated conditions), our results revealed that both active pharmaceutical ingredients (API) show satisfactory stability up to 30 days of storage/usage, with a significant and consistent concentration decline of cyclosporine A after this time point when its hydroalcoholic formulation was kept at 25 °C.