Polymeric micelles as drug stabilizers: the camptothecin and simvastatin cases

Polymeric micelles are appealing drug nanocarriers due to their role as solubilizers of hydrophobic drugs and to their suitability for tuning drug bioavailability and biodistribution. Although implicit in their ability to host drugs, the usefulness of polymeric micelles as protective agents has been less studied. In this review, the potential of diverse amphiphilic block copolymers for creating microenvironments in which labile drugs are protected against adverse agents is analyzed. Particularly, examples of the success of polymeric micelles in the prevention of the hydrolysis of the lactone rings of camptothecin and simvastatin are presented. The maintenance of the lactone form of camptothecin is essential for the antitumor effect and the safety of the treatment. The lactone form of simvastatin is a prodrug required for efficient intestinal absorption. Amphiphilic block copolymers that lead to relatively hydrophobic cores or that create acidic surroundings are singled out as promising components of micelles in which the chemical stability of the drug is favored.