Stability of bioreductive drug delivery systems containing melphalan is influenced by conformational constraint and electronic properties of substituents.

The stability of bioreductive drug delivery systems (TDDS) was monitored at various pH values and in the presence of glutathione (GSH). Results suggest that steric hindrance due to conformational constraint in TDDS led to an increase in stability of TDDS toward nucleophilic degradation under aqueous conditions. The electronic properties of substituents influenced TDDS stability at different pH values and in the presence of GSH.