PURPOSE: Low-dose (0.025%) brimonidine tartrate ophthalmic solution (BTOS) effectively treats conjunctival hyperemia, but contains the preservative benzalkonium chloride (BAK). To minimize risk of ocular irritation—important for postsurgical recovery—preservative-free BTOS (BTOS-PF) was developed. This study evaluated the efficacy of BTOS-PF vs BTOS.

METHODS: This multicenter, double-masked, randomized, active-controlled, parallel-group study in healthy adults with ocular redness was conducted at 6 sites in the US. Participants were randomized 1:1 to BTOS-PF or BTOS, which was self-administered 4 times daily ~4 hours apart for 4 weeks. The primary efficacy endpoint was ocular redness score prior to and at 5(+1), 15(+1), 30(+1), 60(+10), 90(+10), 120(+15), 180(+15), and 240(+15) minutes after investigational drug instillation (0–4-unit scale with half-unit increments). As a secondary, supporting efficacy endpoint, participants were also assessed for latency to onset, including measurements at 1 and 5 min post-instillation.

RESULTS: Baseline ocular redness values were comparable between the BTOS-PF (n=190) and BTOS (n=190) groups. Post-instillation redness at all timepoints were comparable between groups and upper confidence limits at all timepoints fell within the predetermined noninferiority limit of 0.22 units. Ocular redness decreased swiftly after instillation with activity seen within 1 minute for both BTOS-PF and BTOS. The mean difference in change from baseline between the BTOS-PF and BTOS groups for Visit 1, minute 1 and Visit 2, minutes 1 and 5 ranged from -0.03 to 0.01 units. indicating maintained activity and statistical non-inferiority between treatment groups.

CONCLUSION: The study met its primary endpoint of statistically noninferiority of BTOS-PF to BTOS in reducing ocular redness. Both BTOS-PF and BTOS demonstrated rapid onset of action—within 1 min— with activity maintained across study visits. BTOS-PF offers patients a means of address postsurgical redness without the risk of BAK-induced irritation.