TY - JOUR
T1 - Formulations for microprojection/microneedle vaccine delivery
T2 - Structure, strength and release profiles
AU - Raphael, Anthony P.
AU - Crichton, Michael L.
AU - Falconer, Robert J.
AU - Meliga, Stefano
AU - Chen, Xianfeng
AU - Fernando, Germain J.P.
AU - Huang, Han
AU - Kendall, Mark A.F.
PY - 2016/3/10
Y1 - 2016/3/10
N2 - To develop novel methods for vaccine delivery, the skin is viewed as a high potential target, due to the abundance of immune cells that reside therein. One method, the use of dissolving microneedle technologies, has the potential to achieve this, with a range of formulations now being employed. Within this paper we assemble a range of methods (including FT-FIR using synchrotron radiation, nanoindentation and skin delivery assays) to systematically examine the effect of key bulking agents/excipients - sugars/polyols - on the material form, structure, strength, failure properties, diffusion and dissolution for dissolving microdevices. We investigated concentrations of mannitol, sucrose, trehalose and sorbitol from 1:1 to 30:1 with carboxymethylcellulose (CMC), although mannitol did not form our micro-structures so was discounted early in the study. The other formulations showed a variety of crystalline (sorbitol) and amorphous (sucrose, trehalose) structures, when investigated using Fourier transform far infra-red (FT-FIR) with synchrotron radiation. The crystalline structures had a higher elastic modulus than the amorphous formulations (8-12 GPa compared to 0.05-11 GPa), with sorbitol formulations showing a bimodal distribution of results including both amorphous and crystalline behaviour. In skin, diffusion properties were similar among all formulations with dissolution occurring within 5 s for our small projection array structures (~ 100 μm in length). Overall, slight variations in formulation can significantly change the ability of our projections to perform their required function, making the choice of bulking/vaccine stabilising agents of great importance for these devices.
AB - To develop novel methods for vaccine delivery, the skin is viewed as a high potential target, due to the abundance of immune cells that reside therein. One method, the use of dissolving microneedle technologies, has the potential to achieve this, with a range of formulations now being employed. Within this paper we assemble a range of methods (including FT-FIR using synchrotron radiation, nanoindentation and skin delivery assays) to systematically examine the effect of key bulking agents/excipients - sugars/polyols - on the material form, structure, strength, failure properties, diffusion and dissolution for dissolving microdevices. We investigated concentrations of mannitol, sucrose, trehalose and sorbitol from 1:1 to 30:1 with carboxymethylcellulose (CMC), although mannitol did not form our micro-structures so was discounted early in the study. The other formulations showed a variety of crystalline (sorbitol) and amorphous (sucrose, trehalose) structures, when investigated using Fourier transform far infra-red (FT-FIR) with synchrotron radiation. The crystalline structures had a higher elastic modulus than the amorphous formulations (8-12 GPa compared to 0.05-11 GPa), with sorbitol formulations showing a bimodal distribution of results including both amorphous and crystalline behaviour. In skin, diffusion properties were similar among all formulations with dissolution occurring within 5 s for our small projection array structures (~ 100 μm in length). Overall, slight variations in formulation can significantly change the ability of our projections to perform their required function, making the choice of bulking/vaccine stabilising agents of great importance for these devices.
KW - Drug delivery
KW - Formulation
KW - Microneedles
KW - Skin
KW - Vaccine
UR - http://www.scopus.com/inward/record.url?scp=84955499185&partnerID=8YFLogxK
U2 - 10.1016/j.jconrel.2016.01.027
DO - 10.1016/j.jconrel.2016.01.027
M3 - Article
C2 - 26795684
AN - SCOPUS:84955499185
SN - 0168-3659
VL - 225
SP - 40
EP - 52
JO - Journal of Controlled Release
JF - Journal of Controlled Release
ER -