Coupling of a hydrophobic pharmaceutical agents with the hydrophilic poly(ethylene oxide) chain can make the drug water soluble which is necessary for some applications. The modification of the polymer chain results in a different solution behaviour of the macromolecules compared with the unmodified polymer. There are strong indications that shape and rigidity of the modified molecule differ significantly from the simple chain. Some results from measurements of the self‐diffusion coefficient and solution viscosity are discussed. The results are important for further engineering on active drug systems.

A summary of the most recent investigations of conformation and solution properties of a polymer conjugate of the anti‐cancer drug paclitaxel is given. First results of spectroscopic studies of interaction with model proteins in the solid state and in solution are discussed.

Paclitaxel is an antineoplastic agent derived from the bark of the Pacific Yew Tree (Taxus brevifolia). Oral administration of the pure drug is problematic as it has a poor absorption due to its poor solubility in aqueous media. A specific water-soluble prodrug - PP7 - has been introduced by coupling the drug with a water-soluble polymer. For any kind of medical application and administration, knowledge of the binary isobaric phase-diagram is important since it gives information about solubility, phase transitions and the corresponding compositions. The system PP7 + H2O was studied calorimetrically from -20°C and shows the typical behaviour of an eutectic system. The properties of the phase diagram are discussed in view of other solution properties of the system presented earlier.

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The hydrophobic anti‐cancer drug paclitaxel was modified with the hydrophilic poly(ethylene oxide) to a water‐soluble predrug. The modification of the polymer chain results in a different solution behaviour of the macromolecules compared with the unmodified polymer. The phase diagram of the (quasi)binary system predrug‐water was investigated, and molecular simulations of the predrug were executed in vacuum and in the presence of water. The results are important for further engineering on active drug systems.