Interaction between PAMAM-NH₂ G4 dendrimer and 5-fluorouracil in aqueous solution.

The formation equilibrium of poly(amidoamine) dendrimer (PAMAM-NH₂ G4) complex with an oncologic drug such as 5-fluorouracil (5-FU) in water at room temperature was examined. Using the results of the drug solubility in dendrimer solutions and the method of equilibrium dialysis, the maximal number of drug molecules in the dendrimer-drug complex and its equilibrium constant were evaluated. Solubility results show that PAMAM-NH₂ G4 dendrimer can transfer tens 5-fluorouracil molecules in aqueous solution. The number of active sites in a dendrimer macromolecule being capable of combining the drug, determined by the separation method, amounts to n=30 ± 4. The calculated equilibrium constant of the 5-FU-active site bonding is equal to K=(400 ± 120).