Very High Molecular Weight Hyaluronic Acid: A Superior Transport Vehicle for Ocular Therapeutics

Topical drug delivery via eye drops often achieves efficacy at the expense of tolerability. Recent efforts have focused on developing strategies to allow active pharmaceutical ingredients (APIs) to cross ocular surface barriers while minimising adverse effects. However, many of these remain complex, costly and challenging to implement at scale in industrial settings. We highlight here emerging evidence supporting the potential of hylan A, a very high molecular weight hyaluronic acid, as a promising vehicle for topical drug delivery in ocular therapeutics. We explore how the mucoadhesive and viscoelastic properties of a hylan A-based eye drop formulation contribute to extending residence time of APIs on the ocular surface while maintaining patient comfort. Additionally, we examine the role of hylan A in facilitating the dissolution and stabilisation of APIs, as well as in transport across the ocular epithelial barrier without the need for toxic penetration enhancers, thereby preserving ocular surface health. Finally, we present evidence indicating that the intrinsic biological properties of hylan A, including its anti-inflammatory effects, help mitigate side effects commonly associated with certain APIs. To illustrate all these advantages, we examine the pioneering use of a hylan A-based aqueous eye drop formulation as a delivery vehicle for latanoprost, a prostaglandin analogue widely used in the treatment of glaucoma. This case demonstrates the potential of hylan A-based eye drops to support safer and more effective topical drug delivery systems, especially for long-term ocular therapies where tolerability and biocompatibility are critical.