The invention provides a method of inhibiting vascular hyperpermeability in an animal in need thereof. The method comprises administering an effective amount of a diketopiperazme a prodrug of a diketopiperazme or a pharmaceutically acceptable salt of either of them to the animal wherein the diketopiperazme has the formula set forth in the specification. The invention also provides a method of modulating the cytoskeleton of an endothelial cell in an animal. The method comprises administering an effective amount of a diketopiperazme a prodrug of a diketopiperazme or a pharmaceutically acceptable salt of either of them to the animal wherein the diketopiperazme has the formula set forth in the specification. The invention further provides a kit. The kit comprises a diketopiperazme a prodrug of a diketopiperazme or a pharmaceutically acceptable salt of either of them to the animal wherein the diketopiperazme has the formula set forth in the specification.
