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M. K. Shah, D. C. Ritterband, J. A. Liebmann, S. Reddy, J. Chelnis, W. Perez, N. Harizman, J. A. Seedor; Preservative Effectiveness in BAK and BAK-free Glaucoma Medications in a Clinical Setting. Invest. Ophthalmol. Vis. Sci. 2008;49(13):1221. doi: https://doi.org/.
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To assess whether Travatan® Z a preservative free prostaglandin agent is at higher risk for patient contamination than BAK-containing prostaglandin analog when taken by patients at normal dosing schedules.
82 glaucoma patients taking Travatan® (#44) or Lumigan® (#38) were enrolled. Each patient’s current prostaglandin bottle as well as secondary preservative containing control drop (either Timoptic®,Azopt® or Cosopt®) were collected. New fresh bottles of the prostaglandin and secondary drop were dispensed on the day of the visit. However, the Travatan® patients (#44) received a new bottle of BAK-free Travatan® Z in place of Travatan®. Each patient’s new set of drops were collected 2-4 weeks later. The tips and contents of each patient’s bottles were swabbed and inoculated in thioglycolate broth. If turbidity was noted they were subcultured on appropriate media and identification was made through manual methods or using the VITEK 3.
Bacteria were recovered from the tip or contents of 9% of BAK-containing prostaglandin agents (Lumigan® and Travatan®) and from 8% of the BAK-free prostaglandin (Travatan Z®), p>0.05. Of the BAK-containing control drops (Timoptic®, Azopt®, Cosopt®), bacteria were recovered from the tips or contents of 9%. The tips or contents were positive in 1/8 Timoptic® bottles (13%), 5/42 (12%) Azopt® bottles and 10/142 (7%) Cosopt® bottles. These differences were also not statistically significant. Bottle tips were more frequently contaminated than solution in a ~6:1 ratio. Four patients contaminated all 4 bottles accounting for 16 of the 36 (44%) positive cultures.
In a clinical setting, the absence of BAK did not significantly affect the patient contamination rate of the prostaglandin agents. Similar or higher contamination rates of BID or TID dosed control drops Cosopt®, Azopt® and Timoptic® points toward patient factors as the leading cause of contamination. This is also supported by the finding that 4 of 82 patients accounted for 44% of the positive cultures. Education towards proper instillation techniques should be emphasized in all patients using chronic drops. Clinicians should consider all factors (e.g., corneal health, IOP control, and dosing frequency) in determining the best product choice for their patients.
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