By Nina Patterson, Study Director II for Nelson Labs’ Pharmaceutical Department
Over the past couple of years, the Food and Drug Administration (FDA) has started enforcing eye contact solution makers to provide stability testing data or procedures to control temperature when shipping to ensure the efficacy claim is still appropriate after exposure to various time and temperatures. As a result, these manufacturers should conduct Stand-Alone (Kill Time) testing with stability samples to ensure the efficacy claim of the contact solutions.
Stand-Alone testing. The Stand-Alone (Kill Time) test may be used to evaluate the efficacy of solutions designed to disinfect contact lenses. The test is conducted by inoculating each sample of the test solution with one of five recommended organisms and then at specified time intervals evaluating the anti-microbial efficacy of the solution (how many of the organisms have been eliminated compared to a control sample.) The test efficacy is measured at 25 percent, 50 percent, 75 percent, and 100 percent of the product’s minimum disinfection time for all organisms specified in the standard, as well as 400 percent of the product’s minimum disinfection time for fungi. The testing intervals are generally at 1.5-hours, 3-hours, 4.5-hours and 6-hours for all test organisms and 24-hours for fungi.
Stability Samples. Stability samples can be viewed as samples that are being evaluated at particular times incorporating various temperatures. There is potential that prolonged shelf life and environmental conditions could change the efficacy of the disinfectant, or possibly the sterile barrier. The Stand Alone test focuses on the efficacy while other packaging tests focus on the sterile barrier.
Ultimately, manufacturers need to be able to show that the disinfectant efficacy is not compromised when the solution is exposed to various temperatures for a designated period of time as a result of the manufacturing, shipping, storage or use of the disinfectants.