Dissolving Microneedles Containing Lactoferrin Nanosuspension for Enhancement of Antimicrobial and Anti-Inflammatory Effects in the Treatment of Dry Eye Disease.

Dry eye disease (DED), also known as "keratoconjunctivitis sicca", is a common chronic ocular surface disease accompanied by inflammation and diminished tear production. Bovine Lactoferrin (BLF), a multi-functional iron-binding glycoprotein found in tears, decreased significantly in patients with DED, used for the treatment of dry eye, conjunctivitis, and ocular inflammation. BLF has limited therapeutic efficacy due to poor ocular bioavailability. This study developed and optimized a BLF-loaded nanosuspension (BLF-NS) using the Box-Behnken Design (BBD). Optimized BLF-NS was then incorporated with polyvinyl pyrrolidone (PVP) and hydroxypropyl methyl cellulose (HPMC) dissolving microneedles (MNs). The formulations were characterized by Scanning and transmission microscopy, DSC, FTIR, ex vivo studies in corneal tissue from sheep and tested for its antibacterial and antifungal efficacy against Methicillin-Resistant (), , and , respectively. Moreover, they were tested for their Benzalkonium chloride (BCL) dry eye in a rabbit model. The optimized nanosuspension showed a vesicle size of (215 ± 0.45) nm, a Z.P (zeta potential) of (-28 ± 0.34) mV, and an Entrapment Efficiency (EE%) of (90 ± 0.66) %. The MNs were fabricated using a ratio of biodegradable polymers, PVP/HPMC. The resulting BLF-NS-MNs exhibited sharp pyramidal geometry with high mechanical strength, ensuring ocular insertion. In vitro release showed 95% lactoferrin release over 24 h, while ex vivo permeation achieved 93% trans-corneal delivery. In vivo, BLF-NS-MNs significantly reduced pro-inflammatory cytokines (TNF-α, IL-6, MMP-9, IL-1β, MCP-1) and upregulated antioxidant and anti-inflammatory genes (PPARA, SOD 1), restoring their levels to near-normal ( < 0.001). The nanosuspension combined with MNs has shown higher ocular tolerance against DED ensured by the Draize and Schirmer Tear Test.