Phase 2 Study

A phase 2 study is generally the first trial in patients. The primary purpose of a phase 2 study is to provide the first indications on the safety and efficacy of the drug or device being tested. This is the study phase where optimized interventions and clinical end points are established. A control group meeting strict inclusion/exclusion criteria is used. Other important information obtained by phase 2 study is the determination of doses, dosing ranges, and research conditions for phase 3 study as well as common short-term side effects and associated risks. A phase 2 study is populated by 100 to 300 patients who have a condition the study item is designed to treat, diagnose, or prevent. This study phase is often conducted in hospitalized patients under close monitoring. Several thousand patients may be enrolled in an expanded phase 2 study. Information obtained from this study phase helps refine subject inclusion/exclusion criteria by age, comorbidity, and illness symptomatology. The pharmacokinetic differences between healthy volunteers and patients are also assessed. Additional information obtained from phase 2 study includes dose response, best patient type, and frequency of dosing. These data provide the basis for refining the protocol and evaluating its theoretical framework and constructs. The outcome of a phase 2 study may be different from what is ultimately used in phase 3.

Some pharmaceutical companies subdivide this study phase into either phase 2A or phase 2B. Phase 2A studies are designed to evaluate dosing, whereas phase 2B studies are designed to determine the effectiveness of the drug. This phase of study represents the most rigorous demonstration of a medicine's effectiveness. For example, a phase 2 study might be titled “A Double-Blind Study Evaluating the Safety and Efficacy of 1 mg/kg of Test Drug X vs. Placebo in Disease State Patients.”