This study found that oral carbonic anhydrase inhibitors have a low incidence of adverse events. Photo: Olga DeLawrence on Unsplash

New research reporting a low risk of severe adverse reactions to oral carbonic anhydrase inhibitors suggests clinicians’ reluctance toward prescribing the drugs may warrant reconsideration.

The longitudinal cohort study spanned 25 years and included 128,942 patients of similar demographics who were 65 and older. The authors reported an absolute risk of a severe adverse event of 2.9 per 1,000 patients prescribed oral medication and 2.1 per 1,000 patients prescribed topical medication. The difference amounted to a low risk ratio of 1.40, which did not change after controlling for confounders such as diabetes. More comorbidities and clinic visits were also associated risk factors.

Patients who experienced at least one of three idiosyncratic adverse events—Stevens-Johnsons syndrome, toxic epidermal necrolysis or aplastic anemia—were considered to have a severe reaction to therapy. Rates were “was mostly unrelated to patient characteristics,” the researchers wrote in their study. “The pattern was consistent regardless of age, sex and socioeconomic status.”

The researchers concluded that oral carbonic anhydrase inhibitors are safe due to the low incidence of adverse events. However, they cautioned, “Oral carbonic anhydrase inhibitors should not be initiated casually, and appropriate informed consent discussions must be had with patients initiating these agents.”

Popovic MM, Schlenker MB, Thiruchelvam D, et al. Serious adverse events of oral and topical carbonic anhydrase inhibitors. JAMA Ophthalmol. January 27, 2022. [Epub ahead of print].