| Minineedles (e.g. Macroflux microprojection array) |
Various antigens |
In this system, a titanium microprojection array with an adhesive patch backing is used. The antigen is adsorbed as a powder onto the minineedles and injected subcutaneously (at a depth of about 100 μm) by patch application to the skin |
| Needle-less injection |
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| Spring powered (Advantajet, Injex, Vitajet 3, Medi-Jector) |
Hepatitis A, flu antigens, hepatitis B |
Spring-powered needle-free devices have been initially designed and used in humans for the administration of insulin or growth hormones. Volumes of 20–500 μl can be administered subcutaneously. Changing the orifice size modulates the administration pressure, in relation to differences in the thickness of skin between patients |
| Gas powered (Biojector 2000, Penjet, J-Tip, Powderject system) |
Many DNA plasmids plasmids |
Gas-powered systems includes nitrogen, CO2 or helium gas powered systems, allowing i.m., subcutaneous orintradermal administration. Such systems allow the administration of volumes of up to 1 ml. Although most systems have been designed to administer antigens as a liquid, one system (Powderject) relies on a pre-filled helium-powered system in which dry-powder formulations, stable at room temperature (e.g. plasmid DNA) are precipitated onto small (3 μm diameter) gold particles for administration through the skin |
| Patches for transcutaneous immunization |
Shigella or Salmonella antigens, CS6 (E. coli), LT |
The antigen in combination with an adjuvant (e.g. CT or LT) are administered onto hydrated skin. In various animal models, and more recently in humans, this approach was found to elicit antibodies (both IgGs and IgAs), as well as a strong lymphoproliferative response, in the absence of any adverse event35
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| Aerosol for delivery of powder vaccines |
Measles |
In order to produce fine particles without damaging activity of the virus, a live attenuated measles virus is micronized by jet milling to generate particles with the appropriate size for pulmonary delivery (1–5 μm). Particles are blended with an inert carrier to improve aerosol dispersion with a nebulizer36
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