A new formulation of travoprost (Travatan Z, Alcon Laboratories) containing an ionic-buffered preservative (sofZia), and the older formulation (Travatan), preserved with benzalkonium chloride (BAK), had similar IOP-lowering effects in a group of patients who began treatment with the original drop then switched to the newer drug. The ionic-buffered agent is intended to be less toxic to the ocular surface than BAK, which could be significant in long-term glaucoma therapy.
Fort Lauderdale, FL-A change in the preservative used in the IOP-lowering agent travoprost 0.004% does not appear to alter the drug's efficacy, suggest results of a retrospective chart review of patients whose treatment was switched from the original formulation to a new one. Travoprost (Travatan, Alcon Laboratories) contains benzalkonium chloride (BAK), whereas the new drop (Travatan Z) has a preservative (sofZia) that is an ionic-buffered agent and is intended to be less irritating to the ocular surface.
"Early results show that as far as the penetration into the eye, the preservative-BAK versus the more mild [ionic-buffered preservative]-doesn't have much effect on pressure lowering," said Eric H. Leung, MD, an investigator for the study who presented a poster on the findings here at the annual meeting of the Association for Research in Vision and Ophthalmology.
No differences were found in mean IOP at 6 weeks or 3 months after the treatment was switched to the new formulation when compared with the mean of three IOP measurements attained before the change in therapy, said Dr. Leung, a resident in the Loyola University Health System Department of Ophthalmology, Chicago.
Other investigators also have evaluated the new formulation of travoprost in animal models and in human trials, Dr. Leung noted. A recent study by Gross, et al. [J Glaucoma. 2008; 17:217-222] found that the two drops had similar efficacy and safety; in that study, patients were randomly assigned to receive either of the formulations rather than switched from one to the other.
In the study performed by Dr. Leung and colleagues, the primary outcome was the difference in IOP with the newer formulation versus mean IOP with the original drop. IOP measurements were taken at 6 weeks and 3 months following the switch; 6-month data also will be obtained and analyzed.
Before and after
In the patients who had been using the BAK-containing formulation as monotherapy, the outcomes were similar following the transition to the newer drop, indicating no difference in effectiveness. The mean IOP measurement for the right eye while patients were taking the older medication was 15.25 ± 3.36 mm Hg. Following the switch to the newer formulation, the mean IOP in the right eye at 6 weeks was 15.84 ± 3.40 mm Hg (p = 0.45); at 3 months, the mean IOP was 14.69 ± 2.82 mm Hg (p = 0.46). The mean IOP in the left eye while patients were taking the older drop was 15.07 ± 3.21 mm Hg. After the switch, the mean IOP was 16.37 ± 3.71 mm Hg at 6 weeks (p = 0.08) and 14.60 ± 2.71 mm Hg at 3 months (p = 0.27).
Similar results were seen in the group of patients who were taking the BAK-containing formulation plus other IOP-lowering drops. For the right eye, the mean IOP was 16.30 ± 3.60 mm Hg with the original drug, 15.70 ± 4.26 mm Hg with the newer formulation at 6 weeks (p = 0.12), and 15.09 ± 6.85 mm Hg with the newer drop at 3 months. For the left eye, the mean IOP was 16.15 ± 4.09 mm Hg with the BAK-containing formulation, 15.90 ± 3.56 mm Hg with the newer version at 6 weeks (p = 0.16), and 15.02 ± 3.32 mm Hg with the newer drop at 3 months.
Those results indicate that the response to the older and newer formulations was similar in patients who were using either of those drugs as monotherapy or in combination with other glaucoma drops. The incidence of adverse effects also seemed to be similar between the two formulations, Dr. Leung said.
The use of glaucoma medications with less-irritating preservatives, such as the ionic-buffered agent, is particularly important given that glaucoma treatment typically is long term and that many patients one day may need surgery, said Vandana K. Badlani, MD, co-author of the study. Avoiding drugs that potentially are toxic to the conjunctival endothelium could keep the eye healthier and improve the likelihood of a successful surgical outcome, she added.
Dr. Badlani is an assistant clinical professor at the VA Hospital and a faculty member at Loyola University.