clinical trial phase clinical trial phase 1 http://purl.obolibrary.org/obo/NCIT_C15600 C15600 Phase I C0920321 A clinical trial phase that represents the first-in-man trial, which tests within a small group of people (typically 20-80) to evaluate safety, determine safe dosage ranges, and begin to identify side effects. A drug's side effects could be subtle or long term, or may only happen with a few people, so phase 1 trials are not expected to identify all side effects. Leon Li, Asiyah Lin, Oliver He Phase 1 https://en.wikipedia.org/wiki/Clinical_trial