Validation of UV-Vis Spectrophotometric Method for Stability Evaluation of 5% Extemporaneous Vancomycin Eye Drops in Various Vehicles

UV-Vis spectrophotometric method was validated for the stability assessment of 5% extemporaneous vancomycin eye drops in different vehicles. The eye drops were extemporaneously prepared by dissolving vancomycin in various vehicles, including sterile water for injection (SWI), 0.45% normal saline (0.45%NSS) and artificial tear. The solutions were stored at room temperature and in refrigerator for 30 days. The content of vancomycin was measured by UV-Vis spectrophotometer at 280 nm. UV-Vis Spectrophotometric method was validated according to ICH guideline. The results indicated that the method was precise and accurate. The calibration curve was linear with r 2 = 0.9997 in the range of 40-160 μg/mL. LOD and LOQ were 3.39 and 10.26 μg/mL, respectively. The results showed that the percentage of vancomycin residual concentation in SWI and 0.45%NSS was decreased to less than 90% after storage at room temperature for 8 days, whereas the residual concentration of vancomycin in artificial tear was less than 90 % after 10 days in room temperature. Meanwhile the percentage of vancomycin residual concentation in all formulations was remarkably decreased to less than 90% after storage in refrigerator for 17 days. The physical appearance of eye drops in artificial tear remained unchanged. However the observed color of other formulations was gradually changed to yellow in day 7 at room temperature and day 17 in refrigerator. The pH values of all preparations were within the general U.S. pharmacopeia national formulation range of 2.5-4.5. In conclusion, the eye preparations of 5%w/v vancomycin in all selected vehicle were stable for 17 days in refrigerator (2-8°C).