Phase 2 trials include a small number of ill patients, and test the drug's effectiveness, toxicity, safety, and tolerability at various dosages. The trials seek to find appropriate dosage levels, and typically involve the participation of several medical centers.
第二期臨床試驗則加入少數病患，在數種高低不同的劑量中研究藥物的療效、毒性、忍受度、安全性等，從中找出一個最適合的劑量，通常是好幾個醫學中心一起做。