I think Placebo-controlled trials is ethical and necessary because Using placebos in clinical research helps scientists more clearly understand whether a new medical treatment is safer and more effective than no treatment at all. This is not always easy because some patients get better in a clinical trial even when they don’t receive any active medical treatment during the study. And also in order to best determine whether a new medical treatment is safe and effective, PCTs is necessary for researches to perform, which will allow the researchers to gather meaningful and useful scientific information about the safety profile of a new therapy and its effectiveness in treating a specific medical condition. I think it PCTs has balance of advantage and disadvantage because we don’t know what would be the out come of the drug because every both react differently to the drug, disadvantages for the first people using drugs maybe they do not have the best doses, or that they risk resistance if other newer drugs aren’t allowed in the study. The advantages may be that despite these problems, the drugs have still been life-saving, and the person is still alive to benefit from the next drugs in the system.