[Hydrophobic modification of polyelectrolytes as solubility enhancers in preparations for parenteral administration]

Up to now there is no excipient for the solubilization of poorly watersoluble drugs that can be used without limitations in pharmaceutical preparations for intravasal application. The available surfactants show considerable hemolytic activity, cause anaphylactic reactions are chemically instable or have no sufficient solubilizing capacity. By polymerisation of non-ionic surfactants amphiphilic side-chain-polymers are obtained which show in vitro the same solubilization capacity as the monomers but exhibit practically no hemolytic activity. The objective of this work was to investigate, if this findings are also true for ionic oligomers. For this purpose, polyacrylic acids were substituted with long-chain alkyl amines. The solubilization capacity of these oligomers exceeds that of non-ionic amphiphilic side-chain-polymers and that of other surfactants. The hemolytic activity of the oligomers was below that of common ionic surfactants. The solubilization capacity as well as the hemolytic activity depends on the oligomers degree of substitution. Considering their high solubilization capacity and their low hemolytic activity, these oligomers may be excipients in preparations for parenteral application.