Gabapentin Raises Risk of Acute Angle Closure

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The gabapentinoids gabapentin and pregabalin are among the most commonly prescribed drugs in North America. Now, researchers have found an association between gabapentin and the incidence of acute angle-closure glaucoma (AAG).¹ A similar association was not found for pregabalin.

Both drugs are approved to treat epilepsy and selected chronic pain con­ditions and are widely used off-label for mood disorders and pain.² “We were surprised that this commonly prescribed psychotropic agent might increase the risk of AAG,” said coau­thor Mahyar Etminan, PharmD, MSc, at the University of British Columbia Eye Care Center in Vancouver, British Columbia, Canada.

The bottom line, he said: “If you see patients with acute angle-closure glaucoma and they are on gabapentin, this drug might be the culprit.”

RX LINK. Additional evidence has emerged of a link between acute angle-closure glaucoma (shown here) and gabapentin use.

Study rationale. Previously, gab­apentin has been linked to AAG, but only in case reports citing complaints of blurred vision, nystagmus, diplopia, and visual defects. These reports, plus the wide use of the drug, factored into the decision to conduct a large epide­miological study, Dr. Etminan said.

Study specifics. Researchers evalu­ated a random sample of 1,307 patients who developed AAG after gabapentin and pregabalin exposure in the year before diagnosis. The sample, drawn from a medical and pharmaceutical claims database over a 10-year period ending Dec. 31, 2016, also included 13,070 controls.

Who’s at risk? Gabapentin use in the year before AAG diagnosis was associated with a 42% increase of AAG, the researchers found. However, no associa­tion was found for current use of either gabapentin or pregabalin.

In addition, the incidence of AAG was associated with moderate drug exposure (3-5 prescriptions in the year before diagnosis). In contrast, neither limited exposure (1-2 prescriptions) nor significant exposure (6 or more) yielded an association with AAG. The small number of cases identified for significant exposure may have affected results, the researchers noted.

Method of action? The authors theorized that the mechanism of AAG associated with gabapentin use is sim­ilar to that of topiramate with regard to forward displacement of the ciliary body.

Clinical implications. While the findings need to be validated by other studies, Dr. Etminan suggested that ophthalmologists closely evaluate pa­tients diagnosed with AAG who are on gabapentin. He added that it’s possible that patients with a previous history of AAG might be able to safely take pre­gabalin instead.

—Miriam Karmel

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1 Browne MJ et al. J Glaucoma. 2019;28(9):777-779.

2 Goodman CW, Brett AS. JAMA Intern Med. 2019;179(5):695-701.

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Relevant financial disclosures—Dr. Etminan: None.

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