|•||• Phase II trials enroll a larger number of patients (generally between 100 and 1,000) and randomly assign them to the experimental drug treatment and a control treatment, which can be a placebo (an inactive substance that mimics the drug in appearance) or a standard treatment for the condition under study. Then, the outcomes of interest (i.e., remission of pneumonia or a tumor; survival or death) are compared in the two arms of the study. These so-called randomized, controlled trials are the "gold standard" by which the FDA determines whether a drug is effective for the condition being studied. Some of these trials are doubleblinded; that is, neither researcher nor patient knows which participants are getting the new drug and which the control. This is to reduce the possibility of bias, in which researchers treat some patients better from an unconscious (or conscious) belief that one treatment is better than the other.|
|•||• Phase III trials are larger and more definitive versions of Phase II. Before AIDS, a company
had to finish at least two Phase II/III trials before the FDA would allow it to license a new
drug. Now, however, following the example of AZT, only one Phase II trial is usually required
before FDA approval. Indeed, AZT's cousin drug ddI was approved while the Phase II trials
were still ongoing.|
Once the new drug has proven its "safety and efficacy" to the drug company's satisfaction, it applies to the FDA for a license to sell the drug, or a New Drug Application (NDA). The FDA then reviews the accumulated data and decides whether or not to let the company sell the drug. Oftentimes, FDA requires the company to conduct post-marketing or Phase IV studies to refine further medical understanding of the drug.
ACT UP/ New York. 1989. "A National AIDS Treatment Research Agenda". June.
Broder Samuel. 1989. "Controlled Trial Methodology and Progress in Treatment of AIDS". Annals of Internal Medicine 110( 6): 417-418.
Centers for Disease Control. 1981. "Pneumocystis Carinii in Los Angeles". Morbidity & Mortality Weekly Report 30( 21): 250-252.
-----. 1989. "Guidelines for Prophylaxis Against Pneumocystis Carinii Pneumonia for Persons Infected with Human Immunodeficiency Virus". Morbidity & Mortality Weekly Report 38: 3-5.
Committee on Government Operations. 1991. "Drugs for Opportunistic Infections in Persons with HIV Disease". Hearing before the Human Resources and Intergovernmental Relations Subcommittee of the Committee on Government Operations, August 1, 1990, 218-275.
DeStefano E., R. M. Friedman, A. E. Friedman-Kien, J. J. Goedert, D. Henricksen, O. T. Preble , J. A. Sonnabend, and J. Vilcek. 1982. "Acid-Labile Human LeukocyteInterferon in Homosexual Men with Kaposi's Sarcoma and Lymphadenopathy"