(M1530-12-67) Arginine Coated Self-Emulsifying Nanoglobules for Nasal Delivery of Insulin

Purpose: Most of the commercial Insulin formulations are delivered by subcutaneous, intramuscular, or intravenous routes, which is patient inconvenient due to their invasive nature that may further lead to hypertrophy or atrophy of the tissue at injection site. The only available non-invasive commercial formulation Afrezza®, a rapid acting insulin formulation via inhalation route, has also been reported to cause a decline in lung function over time, cough, irritation, and acute bronchospasm in asthmatics. Nasal route is a potential non-invasive route for rapid absorption of drugs due to its relatively porous and thin membrane with abundant vascularity. However, the hydrophilic and macromolecular nature of Insulin makes it difficult for itself to permeate through lipid membrane by itself. Self-emulsified nanoemulsion has the potential to offer enhanced permeability of loaded drug across nasal membranes due to its nanosized oil droplets surrounded by surfactant and ability to permeate through mucus layer. In this context, the purpose of our research was 1. To explore Arginine-coated nanoglobules (LANano) for nasal delivery of Insulin. 2. To evaluate the biocompatibility and permeability of LANano across nasal mucosa along with their colloidal properties and ability to retain structural integrity of Insulin.

Methods: Batches of Insulin and Arginine-loaded nanoglobules were prepared. The colloidal properties, e.g., particle size, polydispersity index and zeta potential of Insulin-loaded formulations were investigated by dynamic light scattering particle size analyzer. The structural integrity and structural component of Insulin and the developed formulation were compared using Circular Dichroism method. The biocompatibility and permeability assay using transwell were conducted on the Calu-3 cell line. Calu-3 is a human airway adenocarcinoma epithelial cell that forms monolayer with tight junctions and exhibits the mucus layer that consists of mucin genes 5 (MUC5), the major mucins present in human healthy airway secretions and therefore mimics the human nasal epithelium. Insulin was detected and analyzed by ELISA method. Currently, pharmacokinetic and pharmacodynamic studies on SD rats are being carried out.

Results: As per, Fig. 1A and 1B, the circular dichroism spectrum of INS-LANano produces the characteristic α-helical peak for Insulin at about 208 nm and 222 nm. The decrease of α-helical content to 22% in INS-LANano is possibly due to the charged interaction of Insulin with LAE containing droplets. INS-LANano was found to produce an acceptable droplet size with homogeneity. The particle size, polydispersity index and zeta potential were found to be 9.121 nm, 0.294 and 6.32 mV respectively. (Fig 2A and 2B). Cytotoxicity assessment of LAE alone and INS-LANano on Calu-3 monolayer showed no significant toxicity at the selected concentration for permeability study. Permeability assessment using transwell confirmed a 2.5-times improvement in Insulin permeation from INS-LANano as compared to Insulin solution (Fig. 3). No reduction in TEER values confirmed minimal toxicity to the tight junctions upon LANano exposure.

Conclusion: Arginine coated Insulin nanoglobules was found to improve the permeability of Insulin and therefore could serve as a potential candidate for intranasal delivery of Insulin.


Fig. 1. A) Far-UV CD spectra of Insulin from different formulations (N=3 scans). B) α-helix content of Insulin from different formulations


Fig. 2. A) Particle size analysis of INS-LANano. B) Zeta potential of INS-LANano.


Fig. 3. Permeability assessment of Insulin from different formulations (N=4)