Abstract
Purpose:
In this work, we tested the hypothesis that highly targeted delivery of anti-glaucoma drugs to the supraciliary space using a hollow microneedle allows dramatic dose sparing of the drug compared to topical eye drops. The supraciliary space is the most anterior portion of the suprachoroidal space located below the sclera and above the choroid and ciliary body.
Methods:
A single hollow 33-gauge microneedle 700-800 µm in length was inserted into the sclera and infused anti-glaucoma drugs into the supraciliary space of New Zealand white rabbits. Sulprostone, a prostaglandin analogue, and brimonidine, a α2-adrenergic agonist, were delivered via supraciliary and topical administration at various doses. The drugs were delivered unilaterally and intraocular pressure (IOP) of both eyes was measured by rebound tonometry for 9 h after injection to assess the pharmacodynamic responses. To assess safety of the supraciliary injection, IOP change immediately after intravitreal and supraciliary injection were compared.
Results:
Supraciliary delivery of sulprostone reduced IOP unilaterally in a dose-related response; comparison with topical administration at the conventional human dose showed approximately 1100-fold dose sparing by supraciliary injection. Supraciliary delivery of brimonidine reduced IOP bilaterally in a dose-related response; comparison with topical administration at the conventional human dose showed approximately 500-fold dose sparing. A safety study showed that the kinetics of IOP elevation immediately after supraciliary and intravitreal injection of placebo formulations were similar.
Conclusions:
This study introduces the use of targeted drug delivery to the supraciliary space using a microneedle and demonstrates dramatic dose sparing of anti-glaucoma therapeutics compared to topical eye drops. Targeted delivery in this way can increase safety by reducing side effects and allow a single injection to contain enough drug for long-term sustained delivery.
Keywords: 455 ciliary body •
456 ciliary muscle •
457 ciliary processes