Types of clinical trial

Clinical trials can be of various types such as open label or blinded trials. Blinding is done to eliminate various types of bias that is why double blind randomized clinical trials are considered as gold standard. Blinding may be of various types. In single blind studies patient does not know whether he belongs to control group or test group. In double blind studies both the participant and phycisian do not know about group allocation and only third party know about group allocation. Clinical trials may be placebo controlled or standard controlled. Placebo is an inert pharmacological substance which has no activity of its own. Placebo can be used only only after ethical approval. Placebo can be used only under certain circumstances such as when the disease is not very serious or there is no alternative effective treatment is available.