The Food and Drug Administration and GlaxoSmithKline are notifying physicians of the possibility of new onset or worsening diabetic macular edema associated with drugs containing rosiglitazone.
In a “Dear Health Care Provider” letter posted on the FDA's Medwatch Web site, the drug company said it has received “very rare” postmarketing reports of the disorder. Bernadette King, director of product communications for the company, said the reports were less than 1 in 10,000 people taking the drug.
Ms. King said the connection between the drug and the disorder is unclear. “We don't know if the macular edema is due to the drug, or due to the disease process. But we wanted to make physicians aware of these symptoms.” She said that GlaxoSmithKline has already added new safety information and a precaution in both prescribing and patient information leaflets.
Most patients who experienced macular edema also reported concurrent peripheral edema, the drug company noted. In some cases, the macular edema resolved or improved following discontinuation of the drug; in one case, the edema resolved after dose reduction.
The letter didn't give any advice about changing doses or avoiding rosiglitazone in patients with diabetic retinopathy, which often occurs along with macular edema, or in patients with risk factors for macular edema.
In Canada, however, GlaxoSmithKline and Health Canada have recommended discontinuing the drug and consulting an ophthalmologist in patients who report visual deterioration while on rosiglitazone.
A “Dear Health Care Provider” letter, distributed in late 2005 to Canadian physicians, warns that rosiglitazone “should be used with caution in patients with pre-existing diagnosis of macular edema or diabetic retinopathy.” The letter also mentions that new safety information will soon be included in the drug's leaflet.
“We are working with our other global markets to see how we can best alert prescribers to this information,” Ms. King said.
A search of PubMed identified just one published report of rosiglitazone being associated with diabetic macular edema. A 37-year-old man with type 1 diabetes, who had been taking the drug for 3 years, reported a sudden decrease in visual acuity 1 month after his dose was increased from 2 mg/day to 8 mg/day. Bilateral macular edema was present, as was peripheral edema. Three weeks after the rosiglitazone dosage was decreased to 2 mg/day, his visual acuity had improved to baseline, and the macular edema had resolved (Arch. Ophthalmol. 2005;123:1273–5).
The report's author, Dr. Michael Colucciello, an ophthalmologist in Moorestown, N.J., warned physicians prescribing rosiglitazone and other thiazolidinediones to be aware of the possibility of decreased vision associated with the development of macular edema. “Caution should be exercised when thiazolidinediones are used in those [patients] with nephropathy or congestive heart failure,” he wrote. “Options for the management of rosiglitazone- or thiazolidinedione-induced macular edema with vision loss include dose reduction and discontinuation.”