Obesity — Biologic Effects of Dehydroepiandrosterone (DHEA) in Humans
Citation(s)
Han DH, Hansen PA, Chen MM, Holloszy JO DHEA treatment reduces fat accumulation and protects against insulin resistance in male rats. J Gerontol A Biol Sci Med Sci. 1998 Jan;53(1):B19-24.
Villareal DT, Holloszy JO, Kohrt WM Effects of DHEA replacement on bone mineral density and body composition in elderly women and men. Clin Endocrinol (Oxf). 2000 Nov;53(5):561-8.
Villareal DT, Holloszy JO Effect of DHEA on abdominal fat and insulin action in elderly women and men: a randomized controlled trial. JAMA. 2004 Nov 10;292(18):2243-8.
Interventional studies are often prospective and are specifically tailored to evaluate direct impacts of treatment or preventive measures on disease.
Observational studies are often retrospective and are used to assess potential causation in exposure-outcome relationships and therefore influence preventive methods.
Expanded access is a means by which manufacturers make investigational new drugs available, under certain circumstances, to treat a patient(s) with a serious disease or condition who cannot participate in a controlled clinical trial.
Clinical trials are conducted in a series of steps, called phases - each phase is designed to answer a separate research question.
Phase 1: Researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
Phase 2: The drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety.
Phase 3: The drug or treatment is given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
Phase 4: Studies are done after the drug or treatment has been marketed to gather information on the drug's effect in various populations and any side effects associated with long-term use.
