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parallel trialA clinical study in which patients/subjects are randomised to one of two or more differing treatment groups—typically the investigational product and placebo—which receive the assigned treatment during the entire trial.
A research study in which groups of patients are followed for the same time but are given different treatments; e.g., one group may receive an inactive substance while another is treated with a drug whose effectiveness must be determined. The impact of the drug can thus be compared with the placebo at varying times, such as 4 weeks, 4 months, or 4 years after the study begins.
See also: trial