Feasibility of intranasal delivery of thin-film freeze-dried, mucoadhesive AS01B-adjuvanted vaccine powders

Abstract

Intranasal vaccination by directly applying a vaccine dry powder is appealing. However, a method that can be used to transform a vaccine from a liquid to a dry powder and a device that can be used to administer the powder to the desired region(s) of the nasal cavity are critical for a successful intranasal vaccination. In the present study, using a model vaccine that contains the liposomal AS01B as an adjuvant and ovalbumin (OVA) as a model antigen, it was shown that thin-film freeze-drying can be applied to convert the liquid vaccine containing sucrose at a sucrose to lipid ratio of 15:1 (w/w), in the presence or absence of carboxymethyl cellulose sodium salt (CMC) as a mucoadhesive agent, into dry powders. Ultimately, the thin-film freeze-dried AS01B/OVA vaccine powder containing 1.9% w/w of CMC (i.e., TFF AS01B/OVA/CMC1.9% powder) was selected for additional evaluation because the TFF AS01B/OVA/CMC1.9% powder was mucoadhesive and maintained the integrity of the antigen and the physical properties of the vaccine. Compared to the TFF AS01B/OVA powder that did not contain CMC, the TFF AS01B/OVA/CMC1.9% powder had a lower moisture content and a higher glass transition temperature and was more porous. In addition, the TFF AS01B/OVA/CMC1.9% thin films were relatively thicker than the TFF AS01B/OVA thin films without CMC. When sprayed with the Unit Dose System Powder (UDSP) nasal device, the TFF AS01B/OVA powder and the TFF AS01B/OVA/CMC1.9% powder generated similar particle size distribution curves, spray patterns, and plume geometries. Importantly, after the TFF AS01B/OVA/CMC1.9% powder was sprayed with the UDSP nasal device, the integrity of the OVA antigen and the AS01B liposomal adjuvant did not change. Finally, a Taguchi L8 orthogonal array was applied to identify the optimal parameters for using the UDSP device to deliver the TFF AS01B/OVA/CMC1.9% vaccine powder to the middle and lower turbinate and the nasopharynx regions in both adult and child nasal casts. Results from this study showed that it is feasible to apply the TFF technology to transform a nasal vaccine candidate from liquid to a dry powder and then use the UDSP nasal device to deliver the TFF vaccine powder to the desired regions in the nasal cavity for intranasal vaccination.