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Mathew MacCumber, Howard Shapiro, Lisa Tuomi; Impact of Concomitant Aqueous Suppressants on PRN Treatment with Ranibizumab in the 24 Month HARBOR Study. Invest. Ophthalmol. Vis. Sci. 2014;55(13):3967. doi: https://doi.org/.
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Aqueous suppressants may prolong the clinical effect of intraocular water-soluble drugs such as ranibizumab (RBZ) and reduce the need for as-needed (PRN) retreatment in patients with neovascular age-related macular degeneration (wet AMD). This subanalysis of the phase III HARBOR study evaluated whether the use of select aqueous suppressants (ie, beta blockers [BB] and/or carbonic anhydrase inhibitors [CAI]) reduced the number of RBZ injections required over 24 months in patients with wet AMD.
Patients in the 0.5 mg and 2.0 mg PRN arms of HARBOR (n=475) who received 3 monthly loading doses followed by PRN treatment were categorized based on concomitant therapy for any use vs non-use of a BB, CAI, or a combined BB with CAI (timolol/dorzolamide). Non-use may include other aqueous suppressants. Concomitant medication was classified as oral (O; ie, systemic) or topical (T); topical treatment was stratified by study or fellow eye, but only the study eye was evaluated. No restrictions based on start date or duration of the concomitant therapy were considered for this analysis. Injection frequency outcomes were calculated as the total number of RBZ injections administered through month 24 and the average number of injections received per year over 2 years.
In total, 207 patients in the RBZ PRN groups received concomitant therapy with aqueous suppressants: BBO (n=176), CAIO (n=2), BBT (n=22), CAIT (n=6), and BB with CAI (n=1). The total number of RBZ injections through month 24 was not significantly different between use and non-use of BBO (12.6 vs 13.3), BBO/CAIO (12.5 vs 13.4), BBT (13.7 vs 13.0), CAIT (13.8 vs 13.0), or BBT/CAIT (13.5 vs 13.0). Similarly, the average number of RBZ injections per year over 2 years was not significantly different between use and non-use of BBO (6.3 vs 6.7), BBO/CAIO (6.3 vs 6.7), BBT (6.9 vs 6.5), BBT/CAIT (6.7 vs 6.5), or CAIT (6.9 vs 6.5).
Through 24 months of HARBOR, BBO usage resulted in slightly fewer injections compared with non-use, while BBT or CAIT usage resulted in slightly more injections compared with non-use; however, neither finding was significant. Small patient sample sizes for topical treatment limit the strength of inference. Future analyses may examine whether a minimum duration of concomitant therapy with aqueous suppressants is required to significantly impact injection frequency.
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