Pharmacology in its literal translation means “the science about medicines” (Pharmakon in Greek is “medicine, poison”; logos in Latin means “science”). Nowadays pharmacology is a complex science studying the action of medicines on healthy and diseased organisms, the science about the purposeful search of new medicines and their rational use. A future physician and a pharmaceutist must understand clearly the actual meaning of common terms (approved by the WHO), which characterize drugs and changes in the organism occurred after their introduction.