Byetta (exenatide)

Byetta (exenatide) is a new medication on the market that has it's origins in an interesting place--the Gila monster's saliva. Scientists studying this small lizard noted it could go a long time without eating. They found a substance in it's saliva that slowed stomach emptying, thus making the lizard feel fuller longer. This substance was similar in nature to a gut hormone found in humans known as GLP-1. GLP-1 is broken down in the body by an enzyme called DPP-IV. So, if you could make a substance like GLP-1 that was not so easy to breakdown, this would have potential benefit; thus, the studies began. Ultimately, after modifying this hormone, exenatide (with the trade name Byetta) was developed. Byetta is the first in a new class of drugs for the treatment of type 2 diabetes called incretin mimetics. Byetta has been shown to have many of the same effects on sugar regulation as GLP-1, so it mimics the body's natural physiology for self-regulating blood sugar. Namely, it slows the release of glucose from the liver, slows stomach emptying thereby regulating delivery of nutrients to the intestine for absorption, and works centrally in the brain to regulate hunger.
Byetta is indicated as additional therapy to improve control of blood sugars in patients with type 2 diabetes who are taking metformin, a sulfonylurea, or a combination of metformin and a sulfonylurea but who have not achieved adequate sugar control. It enhances the way the insulin producing beta cells in the pancreas work. Insulin secretion increases only when blood sugars are high and decreases as blood sugars approach normal. In addition to enhancing the normal physiology of the beta cell, Byetta suppresses glucose release from the liver, slows stomach emptying and the absorption of nutrients including carbohydrate, and reduces intake of food.
Just like Symlin, Byetta is given by injection, but it is given twice a day (usually before breakfast and dinner meals). It comes in a disposable pen form and is available in two doses. The goal is to start with the lower dose for a month or so and then move up to the higher dose if needed and if tolerated. Similar to Symlin, the main side effect is nausea, most likely due to its effects on stomach emptying. This medication is temperature sensitive and it was recommended that the pens be stored at 36-46 degrees F. Recently, this has changed, with a recommendation that unopened pens be refrigerated, and once opened, the pens can be left at room temperature. The risk of hypoglycemia is still a possibility with Byetta, especially when used in combination with sulfonylureas. Your physician may choose to decrease the dose of some of your other medications when initially evaluating how you respond to Byetta.
Similar to Symlin, weight reduction is seen with Byetta in the majority of patients. This makes it particularly suitable for the typical patient with type 2 diabetes who is also overweight. For more, please read the drug information pamphlet on exenatide (Byetta).
A longer acting from of Byetta is currently being considered for approval by the FDA. This would allow for the same benefits (and side effects) without need for such frequent injections.