Clinical trials involving new drugs are commonly classified into four phases. Each phase of the drug approval process is treated as a separate clinical trial. The drug-development process will normally proceed through all four phases over many years. If the drug successfully passes through Phases 1, 2, and 3, it will usually be approved by the national regulatory authority for use in the general population.
- Phase 1: Screening for safety
- Phase 2: Establishing the testing protocol
- Phase 3: Final testing
- Phase 4: Postapproval studies
Each phase has a different purpose and helps scientists answer a different question:
In Phase 1 trials, researchers test an experimental drug or treatment in a small group of people (20-80) for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
In Phase 2 trials, the experimental treatment is given to a larger group of people (100-300) to see if it is effective and to further evaluate its safety.
In Phase 3 trials, the treatment is given to large groups of people (1,000-3,000) to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow it to be used safely.
In Phase 4 trials, postmarketing studies delineate additional information, including the treatment's risks, benefits, and optimal use.
Before pharmaceutical companies start clinical trials on a drug, they conduct extensive preclinical studies.
Read more about this topic: Clinical Trial
Other articles related to "phases, phase":
... Agatston divides the South Beach Diet into three phases, each progressively becoming more liberal ... "Phase 1" lasts for the first two weeks of the diet ... "Phase 2" continues as long as the dieter wishes to lose weight ...
... Laves phases are intermetallic phases that have composition AB2 and are named for Fritz Laves who first described them ... The phases are classified on the basis of geometry alone ... Laves phases are of particular interest in modern metallurgy research because of their abnormal physical and chemical properties ...
... The Capitol (首都) belongs to the Phase I of the development ... Le Prestige (領都) belongs to the Phase IIA of the development, launched in late 2009 ... The first phase of Le Prestige, which comprises four blocks, offers a total of 1,688 homes ...
... disorder hypothesis, there is a species-typical courtship process in humans consisting of four phases ... These phases are “(1) looking for and appraising potential sexual partners (2) pretactile interaction with those partners, such as by smiling at and talking to them (3) tactile interaction ... for a pattern of behavior or erotic fantasy in which one of these four phases of sexual interaction is intensified and distorted to such an extent that it appears to be a caricature of the normal, while the ...
... CALPHAD stands for CALculation of PHAse Diagrams ... An equilibrium phase diagram is usually a diagram with axes for temperature and composition of a chemical system ... phases) are stable and regions where two or more of them coexist ...
Famous quotes containing the word phases:
“That man is to be pitied who cannot enjoy social intercourse without eating and drinking. The lowest orders, it is true, cannot imagine a cheerful assembly without the attractions of the table, and this reflection alone should induce all who aim at intellectual culture to endeavor to avoid placing the choicest phases of social life on such a basis.”
—Mrs. H. O. Ward (18241899)
“But parents can be understanding and accept the more difficult stages as necessary times of growth for the child. Parents can appreciate the fact that these phases are not easy for the child to live through either; rapid growth times are hard on a child. Perhaps its a small comfort to know that the harder-to-live-with stages do alternate with the calmer times,so parents can count on getting periodic breaks.”
—Saf Lerman (20th century)
“This socialism will develop in all its phases until it reaches its own extremes and absurdities. Then once again a cry of denial will break from the titanic chest of the revolutionary minority and again a mortal struggle will begin, in which socialism will play the role of contemporary conservatism and will be overwhelmed in the subsequent revolution, as yet unknown to us.”
—Alexander Herzen (18121870)