Which of the following is NOT a characteristic of benzalkonium chloride?

Benzalkonium chloride is primarily known for its role as a preservative and its effectiveness in preventing bacterial contamination in pharmaceuticals and eye care products. It has been widely used in ophthalmic solutions due to its antibacterial properties, allowing it to help maintain the sterility of multi-dose containers and ensure the safety of the product from microbial growth over time.

While benzalkonium chloride can indeed be found in some formulations designed to protect contact lenses, this characteristic is not universally applicable and does not define the compound itself. Instead, its use in contact lens solutions is often criticized because it can irritate the eyes and exacerbate dry eye symptoms. Therefore, while it may be present in certain products aimed at lens care, it is not accurate to say that it inherently "protects contact lenses" in a manner that is beneficial, given its potential adverse effects, particularly for patients with dry eye conditions.

Thus, the statement that benzalkonium chloride protects contact lenses does not accurately reflect its characteristics when considering its impact on eye health.