Microinjection via the suprachoroidal space: a review of a novel mode of administration

Standard ocular drug delivery methods generally are safe and effective for treating diseases of the eye. However, many routes of administration carry the risk of adverse effects due to drug exposure to anterior ocular tissues. Additionally, these delivery methods may not result in high and consistent levels of a therapeutic agent delivered to target tissues for diseases affecting the posterior segment of the eye. Injection into the suprachoroidal space (SCS) represents an alternative method of ocular drug delivery to the posterior segment. SCS injection facilitates targeted distribution to affected chorioretinal tissues for potential efficacy benefits, compartmentalization away from unaffected anterior segment tissues for potential safety benefits, and a high degree of bioavailability. Furthermore, the SCS may serve as a drug depot for long-acting drug delivery of small-molecule suspensions. Until recently, drug delivery to the SCS could be achieved only in the operating room setting with anesthetic immobilization of the eye and surgical dissection through the sclera. A novel microneedle device, the SCS Microinjector® (Clearside Biomedical, Inc) was developed to permit physicians to administer therapies safely and reliably into the SCS in the office setting. Successful use of SCS injection has been demonstrated with triamcinolone acetonide injectable suspension (Xipere®, Bausch + Lomb), a novel formulation optimized for use with the SCS Microinjector®. FDA approval of this combination drug and device for the treatment of macular edema associated with uveitis (UME) was based on outcomes from the phase 3 PEACHTREE study (NCT02595398); other important studies included its long-term observational extension (MAGNOLIA; NCT02952001) and an open-label safety study (AZALEA; NCT03097315). The SCS Microinjector® together with triamcinolone acetonide injectable suspension for use in the SCS presents an opportunity for safe and effective drug delivery for the treatment of UME and, potentially, for broader use with alternate medications to treat other ocular diseases that impact chorioretinal tissues (eg, age-related macular degeneration, diabetic retinopathy, choroidal melanoma).