The disclosure provides methods and materials for improving the pharmacokinetic properties of drugs. For example, a construct is provided having a drug covalently joined to first and second ligands, or a drug covalently joined to a first ligand and a molecular weight increasing moiety. The ligands have affinity for binding partners, and in a physiological fluid, an equilibrium forms between bound and free forms of the construct. The constructs retain most of the drugs activity while simultaneously increasing half life.
