Doxycycline Fails to Slow Diabetic Retinopathy Progression in Small Study

By Will Boggs MD

July 07, 2014

NEW YORK (Reuters Health) - Doxycycline does not appear to improve retinal function or slow diabetic retinopathy progression in patients with mild to moderate nonproliferative diabetic retinopathy (NPDR), according to results from a proof-of-concept clinical trial.

Although there are no FDA-approved therapies known to prevent progression of mild to moderate retinopathy, at least one clinical trial of patients with severe NPDR showed improved foveal sensitivity after oral doxycycline treatment.

Dr. Ingrid U. Scott from Penn State College of Medicine in Hershey, Pennsylvania and colleagues investigated whether oral doxycycline (50 mg/d), a drug known to inhibit retinal microglial activation, could improve or slow deterioration of retinal function and induce regression or slow progression of diabetic retinopathy in patients with mild to moderate NPDR.

Seventeen patients were randomized to placebo and 16 to doxycycline, and 15 patients in each group completed 24 months of follow-up.

After 24 months of treatment, there was no significant difference in visual function or anatomical outcomes between the groups, according to the June 26 JAMA Ophthalmology online report.

One patient in the placebo group and none of the patients in the doxycycline group had an improvement of at least two Early Treatment Diabetic Retinopathy Study (ETDRS) severity levels (P<0.99).

There were no adverse events related to the study drug.

"Perhaps doxycycline has a greater effect on diabetic retinal dysfunction in patients with more advanced diabetic retinopathy, and presumably more intraretinal inflammation, than in patients with earlier stages of diabetic retinopathy," the researchers speculate. "Alternatively, the sample size of the present study may be too small to detect a doxycycline treatment effect."

"Further study to investigate the potential effect of low-dose oral anti-inflammatory agents on diabetic retinal dysfunction and diabetic retinopathy is warranted," they conclude.

Dr. Sobha Sivaprasad from Moorfields Eye Hospital in London, UK has investigated several treatments for diabetic retinopathy. She told Reuters Health via email, "The sample size was too small and the inclusion criteria too specific to mild cases to come to this negative conclusion. Mild retinopathy needs a long follow-up to demonstrate an effect on progression."

"Currently, other than control of diabetes and blood pressure and maybe lipidemia, there are no preventive measures for progression of diabetic retinopathy," Dr. Sivaprasad said.

Dr. Scott did not respond to a request for comments.


JAMA Ophthalmol 2014.


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