Study examines allergy prevalence using brinzolamide 1.0%/brimonidine 0.2% fixed combination with and without β-blocker in glaucoma patients

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Glaucoma management often requires a number of medications as part of a multi-drug regimen and can often result in low adherence as well as side effects. Fixed-dose combinations can increase adherence and reduce adverse effects when compared to standard treatments.

According to a study by a team of Korean researchers, published in BMC Ophthalmology, investigators conducted a retrospective study to examine the prevalence and clinical characteristics of ocular allergy in glaucoma patients administered brinzolamide 1.0%/brimonidine 0.2% fixed combination (BBFC), both with and without a concurrent β-blocker.¹

Of the 272 participants receiving BBFC for the treatment of glaucoma, 176 patients used a β-blocker concurrently, while 96 patients did not. Timolol maleate was the only β-blocker used, with 171 participants receiving prostaglandin analogue (PGA)–timolol fixed-dose combinations and 5 participants using 0.5% timolol-only formulations.

Meanwhile, 68 participants in the study only used BBFC, and 28 used PGA–BBFC. No meaningful intergroup differences were found in the mean age, follow-up time, and glaucoma type. The proportion of men was two-fold that of women in the concurrent β-blocker usage group, whereas sex distribution was equal in the non-concurrent β-blocker usage group.¹

“Allergy prevalence, allergy type, and allergy occurrence time were compared between the concurrent and non-concurrent β-blocker-usage groups,” the investigators wrote. “Ocular allergies were classified and evaluated using Kaplan–Meier survival analysis.

The investigators found that allergy prevalence was 10.23% and 15.63% (p = 0.193), whereas allergy occurrence time was 15.92 ± 13.80 months and 6.26 ± 6.20 months (p = 0.04) in the concurrent and non-concurrent β-blocker-usage groups, respectively.

“Kaplan–Meier survival analysis indicated that half of the allergies in the concurrent β-blocker-usage group occurred within 12.5 months, with the BBFC discontinuation rate gradually increasing up to 36 months,” the researchers wrote in the study. “Contrarily, half of the allergies in the non-concurrent β-blocker-usage group occurred within 3.3 months, with a rapid increase in BBFC discontinuation rate the first 6 months.”

Intergroup differences in allergy types were significant (p = 0.015). Among all patients with allergy, the average allergy occurrence time of blepharoconjunctivitis, papillary conjunctivitis, and follicular conjunctivitis was 12.52, 9.53, and 13.23 months, respectively.¹

Moreover, follicular conjunctivitis tended to occur later than papillary conjunctivitis (p = 0.042). In the concurrent β-blocker-usage group, follicular conjunctivitis was the most prevalent allergy type (61.1%), whereas papillary conjunctivitis was the most common (66.7%) in in the non-concurrent β-blocker-usage group.¹

Concurrent use of β-blocker with BBFC decreases allergy prevalence, delays allergy onset, and predominantly results in follicular conjunctivitis, thereby facilitating longer treatment duration.

The researchers pointed out that the study has some limitations, including the retrospective design and inclusion of patients who discontinued BBFC due to allergy led to unequal follow-up periods between groups.

“This discrepancy could potentially influence the observed allergy prevalence, as evidenced by the Kaplan–Meier survival curves showing trends over longer durations,” they wrote. “If the follow-up period had been the same between two groups, it is possible that the prevalence of allergy may have shown a statistical difference.”

Second, researchers noted there could be a chance for selection bias. Most of the patients (171/176) in the concurrent β-blocker usage group were given timolol as part of the fixed combination with PGA. While the influence of topical timolol is the most likely factor for reduction in allergy rates, the possible interference of the concomitant use of PGA should be considered.

The investigators noted that understanding these characteristics of allergy in BBFC users is useful to manage patients and improve treatment adherence.

“This study provides insights into the role of β-blockers in modulating ocular allergy in BBFC-treated glaucoma patients, highlighting implications for clinical practice and patient education,” they concluded in the study.

Reference:

1. Park, I.K., Bae, S.H., Jeong, J.H. et al. Comparison of allergy prevalence using brinzolamide 1.0% / brimonidine 0.2% fixed combination with and without β-blocker in glaucoma patients: a retrospective cohort study. BMC Ophthalmol 24, 281 (2024). https://doi.org/10.1186/s12886-024-03550-2