Microbial integrity testing for preservative-free drug formulations

Preservative-free formulation can protect patients from the adverse effects of additives and is a growing trend in eye care and nasal drug products.

This paper presents a new tip seal integrity test – TSIT 2.0 – that provides a reasonable and representative challenge for preservative-free solutions with respect to their ability to safeguard microbial integrity. The test uses three germs rather than pseudomonas aeruginosa alone and involves repeated submersion of the discharge orifice during actuation. It is simple, and test duration is relatively short with results generated over a 10-day period. Experimental data are presented to illustrate the application of the new TSIT 2.0 test to an eyedropper. The test is the culmination of a long series of experiments and the results confirm its efficacy for testing the ability of antimicrobial measures to preserve microbial integrity.