P-glycoprotein is a type of protein found in cell membranes that plays a crucial role in transporting various substances across these membranes. It acts as a pump, moving drugs and other compounds out of cells, which can affect how medications work in the body. This protein is particularly important in organs like the liver, kidneys, and intestines, where it helps regulate the absorption and elimination of drugs. The activity of P-glycoprotein can influence the effectiveness of certain medications, as it may reduce their concentration in the bloodstream. Variations in this protein's function can lead to differences in drug responses among individuals, making it a significant factor in personalized medicine. Understanding P-glycoprotein is essential for optimizing drug therapy and minimizing side effects.