Abstract: The invention relates to phosphorylated polyphenols, phosphorylated flavonoids, and phosphorylated pyrone analogs. Methods and compositions for the modulation of side effects of substances using such phosphorylated compounds are described. Methods and compositions are described for the modulation of blood-tissue barrier (BTB) transporter activity to increase the efflux of drugs and other compounds out of a physiological compartment and into an external environment. In particular, the methods and compositions disclosed herein provide lowered side effects when phosphorylated pyrone analogs are coadministered with therapeutic agents.