Method of targeting a specific location in a body using phospholipid and cholesterol liposomes which encapsulate an agent

A method of targeting a tumor in a body with an agent for diagnosis or treatment, comprising:

• a) providing micellular particles of less than 2000 Å comprising phospholipid molecules wherein said particles are stable to leakage in vitro and in vivo, and
• b) modifying a portion of said phospholipid micellular particles to provide for the blockage of the macrophages in the body by such modified phospholipid micellular particles;
• c) initially introducing the modified vesicles into the blood stream of the body to block uptake by the macrophages in the body;
• d) incorporating said agent for diagnosis or treatment into a second group of the micellular particles;
• and
• e) subsequently introducing the second group of phospholipid micellular particles with said agent for diagnosis or treatment into the blood stream of the body to obtain movement of the particles to the tumor.