For a drug to exert its biological effect, it must be transported by the body fluids, traverse the required biological membrane barriers, escape widespread distribution to unwanted areas, endure metabolic attack,(经受代谢改变) penetrate in adequate concentration to the sites of action, a interact in a specific fashion a causing an alteration of cellular functionFor a drug to exert its biological effect, it must be ◼ transported by the body fluids, ◼ traverse the required biological membrane barriers, ◼ escape widespread distribution to unwanted areas, ◼ endure metabolic attack, （经受代谢改变） ◼ penetrate in adequate concentration to the sites of action, ◼ interact in a specific fashion, ◼ causing an alteration of cellular function