Preservative system in recalled drops unique from company's other lines

The preservative system used to manufacture Systane Free Liquid Gel lubricating eye drops (Alcon Laboratories) is distinctly different from that of the company's other products, including travoprost ophthalmic solution 0.004% (Travatan), according to the company.

Alcon is emphasizing the differences in the products' preservative systems to shore up support for its products after it discovered that a faulty preservative in its Systane Free Liquid Gel allowed mold to grow.

The company pulled the product from store shelves Dec. 15 and initiated a voluntary recall with no plans to return it to the market.

The company said its travoprost ophthalmic solution 0.004% for reducing IOP in patients with open-angle glaucoma, however, uses a novel ionic-buffered preservative system called sofZia, which is an extension of its borate/polyol preservative systems. Nitrogen is an essential nutrient for the growth of microbial contaminants.

"Travatan Z solution does not contain any nitrogen source, such as AMP, which is present in Systane Free Liquid Gel," the letter stated.

"Alcon has demonstrated that the sofZia preservative system is robust and withstands multiple challenges of high levels of ocular pathogens, such as Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Candida albicans, and Aspergillus niger," the letter stated. "In addition, other in-use testing with high-level challenges of Fusarium solani, Ralstonia pickettii, Staphylococcus epidermidis, Streptococcus pneumoniae, and Haemophilus influenzae demonstrated that Travatan Z solution is effectively preserved."

The letter was signed by Michael V.W. Bergamini, PhD, vice president, glaucoma development, and Barry A. Schlech, PhD, vice president, pharmaceutical microbiology, both of Alcon Research Ltd.

Meanwhile, the original formulation of Systane uses the Polyquad preservative system, which has been used safely for more than 20 years to prevent contamination of eye-care products, the company said.