Solubilization of aluminum-containing adjuvants by constituents of interstitial fluid

The solubilization of three commercially available aluminum-containing adjuvants by citrate anion was studied. Amorphous aluminum hydroxyphosphate and boehmite were both solubilized, however, amorphous aluminum hydroxyphosphate dissolved significantly faster than boehmite. The results suggest that citrate and other alpha-hydroxy carboxylate anions in the interstitial fluid are able to solubilize and thereby facilitate the excretion of aluminum from aluminum-containing adjuvants which are administered by intramuscular injection. The results also suggest that the release of antigen following administration may be significantly more rapid from an amorphous aluminum hydroxyphosphate-adjuvanted vaccine in comparison to a boehmite-adjuvanted vaccine.