Durezol (difluprednate) is a U.S. Food and Drug Administration (FDA)-approved medication for the treatment of inflammation and pain associated with ocular surgery. Durezol was developed by Sirion Therapeutics, but the company sold its U.S. rights to Durezol to Alcon in 2010.
How Durezol works
Corticosteroids act by binding to the glucocorticoid receptors found on almost every cell in the body. The corticosteroid-glucocorticoid receptor complex then moves to the cell nucleus (the part where genetic material is stored) and either activates anti-inflammatory genes or blocks pro-inflammatory ones.
The exact mechanism by which Durezol performs this anti-inflammatory action in the eye is not fully understood, but it is thought to indirectly inhibit the activity of the enzyme phospholipase A2. Phospholipase A2 has pro-inflammatory properties and plays an essential role in inflammation. By inhibiting phospholipase A2, Durezol may reduce inflammation and thereby decrease granuloma formation in ocular sarcoidosis.
Durezol in clinical trials
Durezol has not been tested specifically in patients with ocular sarcoidosis. However, a number of trials assessed its safety and effectiveness in patients with uveitis, which can also occur as a consequence of ocular sarcoidosis.
A Phase 3 double-blind, randomized clinical trial (NCT00501579) with 90 anterior (affecting the front of the eye) uveitis patients compared the safety and efficacy of Durezol with prednisolone acetate, a corticosteroid used as treatment. Participants received eyedrops either containing 0.05 percent Durezol four times per day or containing 1 percent prednisolone acetate eight times per day. The primary endpoint was the number of cells in the anterior chamber of the eye. The anterior chamber of the eye, usually a cell-free area, tends to have cells in people with anterior uveitis. After 14 days, there was no difference in the number of anterior front chamber cells between the two treatment groups.
Another Phase 3 double-blind, randomized clinical trial (NCT01201798) included 111 patients with anterior uveitis and applied the same treatment mix as in the trial described above. This study also reported no difference in the number of anterior front chamber cells between the two treatment groups. There was, however, a difference in the complete clearing of cells. At day three and again at day 21 (seven days after the treatment stopped), the percentage of patients with complete cell clearance was significantly higher in the group receiving Durezol.
In both trials, Durezol performed as good as prednisolone acetate with the advantage of a lower number of required dosings each day.
A Phase 4 randomized clinical trial (NCT01939691) is planned to start at the Aravind Eye Hospital in India in summer 2018. The trial aims to enroll 108 patients with uveitis who also have macular edema, a build-up of fluid in the macula. The macula is an area in the center of the retina, responsible for sharp and straight-ahead vision. Macula edema is a leading cause of poor vision in uveitis patients.
In the trial, patients will receive either Durezol, a combination of Nepafenac (an anti-inflammatory medication) and prednisolone acetate, or a combination of Durezol and Nepafenac for up to eight weeks.
Corticosteroids suppress the immune response, and the use of Durezol can increase a person’s risk of ocular infections.
Common adverse events of Durezol treatment include blurred vision; headache; stinging, itching, or mild burning in the eyes; dry or watery eyes; and increased eye pressure.
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