Development of Brimonidine-Loaded Ethosomes for Glaucoma: Investigation of Intraocular Pressure-Lowering Potential In Vivo

TL;DR

Researchers developed a new nanocarrier system to improve the delivery of a glaucoma drug, achieving similar effects with a lower dose.

Contribution

A novel ethosomal formulation of brimonidine tartrate was developed and shown to lower intraocular pressure effectively at a reduced dose.

Findings

The optimized ethosomal formulation had a particle size of 122.6 nm and 87.33% encapsulation efficiency.

The ethosomal formulation showed non-irritancy in the HET-CAM test and comparable IOP-lowering effects to conventional eye drops at one-third the dose.

Abstract

Background/Objectives: Brimonidine tartrate (BRT), a selective α2-adrenergic receptor agonist, is commonly used in the treatment of glaucoma. However, conventional eye drop formulations suffer from poor ocular bioavailability and rapid elimination. This study aimed to develop and evaluate BRT-loaded ethosomes as a nanocarrier-based alternative to enhance intraocular delivery and therapeutic efficacy. Methods: Ethosomes were prepared using the thin-film hydration method and optimized via central composite design. The optimized formulation was subjected to physicochemical characterization, in vitro release testing, and ocular irritation assessment using the Hen egg test—chorioallantoic membrane (HET-CAM) model. Additionally, the intraocular pressure (IOP)-lowering efficacy of the formulation was evaluated in a rat glaucoma model. Results: The optimized ethosomal formulation exhibited favorable physicochemical properties, including a mean particle size of 122.6 ± 0.7 nm, zeta potential of −1.8 ± 0.9 mV, and encapsulation efficiency of 87.33 ± 0.04%. In vitro release data followed Higuchi kinetics. HET-CAM analysis indicated non-irritancy. In vivo, the ethosomal BRT formulation achieved comparable IOP-lowering effects to the marketed eye drops at one-third of the dose. Conclusions: The developed BRT-loaded ethosomal system demonstrated promising physicochemical stability, sustained release, and therapeutic potential. These findings suggest that ethosomes may offer a safe and effective strategy for enhancing the ocular delivery of BRT in glaucoma therapy.

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