| abstract |
Improved sustained-release delivery forms comprising Lewis acid-Lewis base salt microparticulate material modified by the addition of at least one additional constituent known as an "adjuvant" selected from the group consisting of carbomers, poloxamers and tetronomers. Adjuvants may assist in the manufacture of the microparticle or may provide additional advantageous characteristics such as assisting in solubilizing a core material or forming of the microparticle wall or both. Adjuvant modified microparticles have improved controlled release characteristics, have greater mechanical and thermal stability and have increased capacity for a wide range of core materials. In general, adjuvants are polyether linkage-containing molecules, adapted by virtue of their otherwise strongly acidic (carbomers or other water soluble compounds with pKa of less than 5), strongly basic (tetronomers or other non-aqueous solvent soluble bases with a pKa of more than 9 or above) or essentially neutral, but extremely weakly basic characteristics (poloxamers or other non-aqueous solvent soluble compounds with a pKa of from 5 to 7) to function as wall-forming or core-forming reactants in the microcapsule-forming reaction of this invention. |