Topical delivery of anti-VEGF macromolecules for retinopathy: A review

Retinopathy is a sight-threatening posterior eye disease involving microvascular complications. Diabetic retinopathy (DR) is the most prevalent form of this. Topical biologics (anti-VEGFs) have better therapeutic outcomes compared to steroids because of minimum adverse effects. However, only invasive methods have been approved, which are associated with serious issues related to patient compliance. Non-invasive administrations of anti-VEGFs have challenges, including stability and penetrability. Investigations on the use of cell-penetrating peptides as carriers for the delivery of biologics have shown encouraging results. Loading the polar biologics into the core of liposomes to capitalize on the lipidic nature and small size for retinal access has also received research attention. However, issues related to the controlled release of these topical biologics for continued retinal access need further attention. Despite the challenges of achieving controlled release in topical application of ocular biologics, there is scope to develop their gels or solid scaffolds. Targeting by capitalizing on membrane transporters of endogenous substances and nutrients has succeeded in brain and other tissue-specific delivery. Thus, there is scope to improve penetrability using a membrane transportation system, as the eye has diverse kinds of membrane transporters that uptake nutrients and endogenous substances.