Chen YE, Drucker DJ Tissue-specific expression of unique mRNAs that encode proglucagon-derived peptides or exendin 4 in the lizard. J Biol Chem. 1997 Feb 14;272(7):4108-15.
Eng J, Andrews PC, Kleinman WA, Singh L, Raufman JP Purification and structure of exendin-3, a new pancreatic secretagogue isolated from Heloderma horridum venom. J Biol Chem. 1990 Nov 25;265(33):20259-62.
Eng J, Kleinman WA, Singh L, Singh G, Raufman JP Isolation and characterization of exendin-4, an exendin-3 analogue, from Heloderma suspectum venom. Further evidence for an exendin receptor on dispersed acini from guinea pig pancreas. J Biol Chem. 1992 Apr 15;267(11):7402-5.
Shadid S, Jensen MD Effect of pioglitazone on biochemical indices of non-alcoholic fatty liver disease in upper body obesity. Clin Gastroenterol Hepatol. 2003 Sep;1(5):384-7.
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.
