Evaluation of extended release brimonidine intravitreal device in normotensive rabbit eyes.

PURPOSE: To evaluate the safety profile of a brimonidine extended release intravitreal implant, in normotensive rabbit eyes. METHODS: Devices were made from hollow poly-l-lactic acid (PLA) tubes and contained hundred micrograms of brimonidine pamoate. Device was injected intravitreally in one eye of 12 New Zealand pigmented rabbits, whereas other eye was injected with a sham implant in masked fashion. Ocular examination was conducted at baseline and months 1, 3 and 6 including dilated fundus examination and electro-retinogram (ERG). Four rabbits were sacrificed at each time-point for retinal histology. ERG data were compared between groups and time-points using anova. RESULTS: No complications were reported from either eye of any rabbits over a 6-month period. Photopic A wave was reduced in the control eye at 1 month compared with baseline (p < 0.01). There was no significant difference in other ERG parameters between the groups at different time-points. Gross retinal histology was normal at all time-points. CONCLUSION: Extended release intravitreal brimonidine device was found to be safe and in normotensive rabbit eyes.

Efficacy of low-release-rate fluocinolone acetonide intravitreal implants to treat experimental uveitis.

OBJECTIVE: To determine the efficacy of 0.5-mg and 0.1-mg sustained-release fluocinolone acetonide intravitreal implants to inhibit ocular inflammation in a rabbit model of severe uveitis. METHODS: The in vitro pharmacokinetic profile of both the 0.5-mg and 0.1-mg sustained-release fluocinolone intravitreal implants was determined during a 10-day period. A sustained-release fluocinolone acetonide intravitreal implant with a release rate of either 0.5 microg/d (n = 16) or 0.1 microg/d (n = 16) was implanted into the vitreous cavity of the right eye in albino rabbits after a subcutaneous injection of tuberculin antigen. Control animals (n = 14) received empty devices. Uveitis was induced with an intravitreal tuberculin antigen injection. A masked observer graded anterior chamber flare, anterior chamber cells, vitreous opacity, and inflammation on histologic sections. RESULTS: In vitro, the drug was released from both devices in a linear manner. In vivo, treated eyes were significantly less inflamed than untreated eyes (P< or =.02). Inflammation was suppressed to a greater degree with the 0.5-microg/d implant compared with the 0.1-microg/d implant. CONCLUSION: Sustained-release fluocinolone intravitreal implants suppress ocular inflammation in a rabbit model of severe uveitis. CLINICAL RELEVANCE: The efficacy demonstrated with the 0.1-microg/d implant provides the rationale for future human studies with lower-release-rate implants than are currently used in noninfectious uveitis clinical trials.