April 01, 2013
3 min read

Comparison of glaucoma meds shows little variation in ocular surface tolerability

Objective clinical measures showed no significant differences among three drugs with differing active ingredients and preservatives.

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Three glaucoma drugs – two prostaglandin analogs and a prostamide – were analyzed in a recent study and found to be statistically comparable in regard to ocular surface tolerability.

“There’s been a lot of talk about the effect of preservatives on the ocular surface, specifically BAK. There is concern that BAK might be really toxic to the surface and that it could really affect patient comfort and tolerability,” Steven D. Vold, MD, one of the study authors, told Primary Care Optometry News. “And that really wasn’t borne out over the course this 12-week study.”

The Allergan-sponsored study examined the surface tolerability of Lumigan (bimatoprost 0.01%, Allergan), Travatan Z (travoprost 0.004%, Alcon) and Xalatan (latanoprost 0.005%, Pfizer) in 164 adult patients diagnosed with open-angle glaucoma or ocular hypertension randomized to three treatment groups. Bimatoprost and latanoprost both have a benzalkonium chloride (BAK) preservative, while travoprost is preserved with a boric acid, propylene glycol, sorbitol and zinc chloride preservative (sofZia, Alcon).

“Patients with open-angle glaucoma or ocular hypertension in this clinical trial were treated for 30 days with latanoprost monotherapy prior to randomization,” Vold said. “At baseline, patients were randomized to once-daily latanoprost, bimatoprost or travoprost monotherapy for 3 months. We compared the ocular surface findings of those patients at baseline and each follow-up visit.”

Steven D. Vold

Steven D. Vold

Corneal staining and tear break-up time were not statistically signifcantly different among the groups at baseline, according to the study.

The ocular surface tolerability assessments included conjunctival hyperemia, corneal staining, tear break-up time and biomicroscopy, with safety assessments for intraocular pressure and adverse events. Measurements were taken at baseline, 1 week, 4 weeks and 3 months, according to the study.

“We weren’t able to find a significant difference between the three medicines, from a statistical standpoint, at 3 months. There was slightly more hyperemia in the travoprost group during the middle stages of the study, but it was a trend that didn’t bear out for the 3 months,” Vold said.

At week 1, the mean conjunctival hyperemia score in patients treated with travoprost jumped by 0.20, while the change from baseline in patients treated with bimatoprost and latanoprost was 0.04 and 0.00, respectively. By the end of the study, all hyperemia scores had mostly returned to baseline values; the differences in values at baseline and 12 weeks were insignificant.

All three medications were well tolerated and safe, according to the study. No significant among-group differences in IOP change from baseline were observed at any follow-up visit. Furthermore, all three treatments were well tolerated, and adverse event incidence rates were comparable among groups.

Treatment-related ocular adverse events included two cases of itchy eyelids in the bimatoprost group; two cases of hyperemia and two cases of dryness in the travoprost group; and one case of ocular itching in the latanoprost group. No treatment-related serious adverse events were reported.

“At 12 weeks, patients had comparable ocular tolerability findings with respect to objective measures of conjunctival hyperemia, corneal staining and tear break-up time. Differences in type of preservative (i.e., BAK vs. sofZia) did not lead to differences in ocular surface tolerability at 3 months,” the study authors said in conclusion.

“The purpose of this study was to validate the fact that the new formulation of Lumigan utilizing 0.01% rather than 0.03% bimatoprost appears to be tolerated at least as well as Travatan Z and latanoprost,” Vold said. “In the past, Lumigan 0.03% may have had a less favorable patient tolerability profile than Travatan Z and latanoprost.

“Again,” said Vold, “this was a 3-month study, so the long-term effects of BAK are not being considered here. Further study is warranted, particularly long-term studies to evaluate tolerability in patients on multiple topical medications and patients with severe ocular surface disease.” – by Daniel R. Morgan

Williams JM, Crichton ACS, Vold M, Hollander DA. Ocular surface tolerability of prostaglandin analogs and prostamides in patients with glaucoma or ocular hypertension. Poster presented at: European Glaucoma Society; September 2012; Copenhagen, Denmark.
For More Information:
Steven D. Vold, MD, can be reached at Vold Vision, 2783 N. Shiloh Dr., Fayetteville, AR 72704; (479) 442-8653; svold@cox.net
Disclosures: This study was supported by Allergan Inc. Vold is an investigator and speaker for Allergan.