Diquafosol Beats Hyaluronate in Treating Dry Eyes

Ricki Lewis, PhD

February 05, 2015

Diquafosol ophthalmic solution is more effective at treating dry eye than sodium hyaluronate (HA) ophthalmic solution, according to results of a large, randomized clinical trial published online January 28 in the British Journal of Ophthalmology.

"The tear film has three layers: aqueous, lipid, and mucin. The majority of current treatments for dry eyes treat abnormalities of the aqueous and lipid layers. More recent studies, such as this one, are now addressing the mucin layer as another treatment option," Neeti B. Parikh, MD, attending physician at Montefiore Medical Center and assistant professor at Albert Einstein College of Medicine, Bronx, New York, told Medscape Medical News.

The most common treatment for dry eye is artificial tears, followed by anti-inflammatories and punctual occlusion therapy. For many patients, the hydrating effect of artificial tears is insufficient if the mucin layer is damaged. Interference with mucin production accounts for about 90% of cases of dry eye. Rose bengal staining highlights areas of mucin deficiency.

"Diquafosol stimulates the mucin and aqueous glands to produce more fluid. Mucin is a natural coating of the cells on the surface of the eye, which protects them and enhances the beneficial effects of aqueous tears. We don't have a good artificial substitute for this layer, and it is vital, so if the body can produce more, that would be a great advantage," Elmer Tu, MD, clinical spokesperson for the American Academy of Ophthalmology and director of cornea service and professor of ophthalmology at the University of Illinois, Chicago, told Medscape Medical News.

Although smaller trials have suggested that diquafosol is effective, the drug has not been tested in a large, multicountry trial. Therefore, Lan Gong, MD, from the Department of Ophthalmology at the Eye, Ear, Nose and Throat Hospital of Fudan University in Shanghai, China, and colleagues randomly assigned 497 patients with dry eye in China and Singapore to either 3% diquafosol ophthalmic solution or 0.1% HA ophthalmic solution, which is a component of some artificial tears. Patients in each arm used one drop six times daily, with endpoints measured at 2 and 4 weeks of treatment.

At week 4, diquafosol met both of the primary endpoints for the trial, including noninferiority in fluorescein score (−2.1 ± 1.5 in the diquafosol group vs −2.0 ± 1.3 in the HA group) and improvement in rose bengal score (−2.5 ± 2.0 vs −2.0 ± 1.9; P = .019).

In addition, secondary endpoints also showed improvements, including in most subjective symptoms. Diquafosol and HA improved tear film breakup time by 1.046 ± 1.797 and 0.832 ± 1.775 seconds, respectively.

Adverse drug reaction incidence rates were 12.2% (30 of 246 patients) for diquafosol and 6.0% (15 of 251 subjects) for HA, but these were mild (irritation, itching, blurring, foreign body sensation, or eye discharge) and could have been caused by the underlying dry eye condition.

The researchers conclude that diquafosol can be an alternative for patients who do not find relief with HA or other artificial tear preparations and might be used in combination with HA for some patients. Limitations of the study include lack of objective examination of mucin status or use of visual analog scales to assess symptom severity and frequency, as well as no Schirmer's test or tests of tear osmolarity.

"The main benefit of this study is that it was on a slightly larger scale than some other studies, and that it was conducted outside of Japan, where the drug is approved for use," said Dr Tu.

Dr Parikh added, "Certain disease processes, such as Steven Johnson syndrome, vitamin A deficiency, and pemphigoid damage goblet cells, decrease mucin production. In these cases, diquafosol would be a good choice."

Diquafosol is not currently marketed in the United States.

The authors, Dr Parikh, and Dr Tu have disclosed no relevant financial relationships.

Br J Ophthalmol. Published online January 28, 2015. Abstract

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