The responsibilities delegated to steering committees or contract research organizations (CROs) by a manufacturer and/or funding agency can vary considerably. It is important that the responsibilities and authorities of the product manufacturer, the funding organization (if different) and any other entity be clearly defined and understood by all parties at the start of the endeavor. Potential conflicts of interest of each party, especially sponsors and clinical investigators (see 21 CFR Part 54) should be carefully considered when determining roles and responsibilities.
A Phase IV trial is also known as postmarketing surveillance trial, or informally as a confirmatory trial . Phase IV trials involve the safety surveillance ( pharmacovigilance ) and ongoing technical support of a drug after it receives permission to be sold (. after approval under the FDA Accelerated Approval Program ).  Phase IV studies may be required by regulatory authorities or may be undertaken by the sponsoring company for competitive (finding a new market for the drug) or other reasons (for example, the drug may not have been tested for interactions with other drugs, or on certain population groups such as pregnant women, who are unlikely to subject themselves to trials).   The safety surveillance is designed to detect any rare or long-term adverse effects over a much larger patient population and longer time period than was possible during the Phase I-III clinical trials.   Harmful effects discovered by Phase IV trials may result in a drug being no longer sold, or restricted to certain uses; recent examples involve cerivastatin (brand names Baycol and Lipobay), troglitazone (Rezulin) and rofecoxib (Vioxx). The minimum time period mandatory for Phase IV clinical trials is 2 years. [ citation needed ]