Part of clinical development in which an investigational new drug is normally tested on healthy human volunteers in order to evaluate its potential toxicity, pharmacokinetic properties and suitable dosage. In the case of anticancer drugs, actual volunteer cancer patients are treated in Phase 1.

Clinical trials usually conducted in healthy human volunteers to determine if a drug candidate is safe for more extensive testing.

The first of three phases of a clinical trial, in which researchers test a new 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.

Preliminary investigation, usually by environmental engineer or consultant, of site's current and past tenancies, adjacent uses, and initial assessment prior to extensive analysis of the possibility or likelihood of site contamination in any manner.

Phase 1 includes the initial introduction of an investigational new drug into humans. These studies are closely monitored and may be conducted in patients with the targeted disease, but are usually conducted in healthy volunteer subjects. These studies are designed to determine the metabolic and pharmacologic actions of the drug in humans, the side effects associated with increasing doses, and, if possible, to gain early evidence on effectiveness. During Phase 1, sufficient information about the drug's pharmacokinetics and pharmacological effects should be obtained to permit the design of well-controlled, scientifically valid, Phase 2 studies. Phase 1 studies also evaluate drug metabolism, structure-activity relationships, and the mechanism of action in humans. These studies also determine which investigational drugs are used as research tools to explore biological phenomena or disease processes. The total number of subjects included in Phase 1 studies varies with the drug, but is generally in the range of twenty to eighty.