Abstract: A composition having general structure (1); wherein the P-gp substrate is a substrate for P-glycoprotein; the linker is a biocompatible polymeric moiety; the drug-loaded carrier comprises a biocompatible framework carrying at least one drug; and the straight line shown in Formula (1) between the drug-loaded carrier and linker represents a first bond, and the straight line shown in Formula (1) between the linker and P-gp substrate represents a second bond. Also described herein are pharmaceutical compositions containing the above compositions, as well as methods for using these compositions for targeted delivery of a drug to cells expressing higher levels of P-glycoprotein compared to other cells in a mammal, for the treatment of various diseases or conditions, such as cancer and neurological conditions.