All of statements about exenatide are true except:
**Core Concept**
Exenatide, a glucagon-like peptide-1 (GLP-1) receptor agonist, is used in the management of type 2 diabetes mellitus. It works by enhancing glucose-dependent insulin secretion, suppressing inappropriately elevated glucagon secretion, and slowing gastric emptying.
**Why the Correct Answer is Right**
Exenatide binds to the GLP-1 receptor, which is a G protein-coupled receptor expressed on pancreatic beta cells. This binding activates the receptor, leading to an increase in intracellular cyclic AMP (cAMP) levels, which in turn stimulates insulin secretion. Additionally, exenatide's action on the GLP-1 receptor suppresses glucagon secretion by inhibiting the release of glucagon from pancreatic alpha cells. The slowing of gastric emptying is thought to be due to exenatide's action on the vagus nerve.
**Why Each Wrong Option is Incorrect**
**Option A:** Exenatide is used as a first-line treatment for type 1 diabetes mellitus. This is incorrect because exenatide is not recommended as a first-line treatment for type 1 diabetes, which typically requires insulin therapy.
**Option B:** Exenatide has a significant effect on lowering blood pressure. This is incorrect because while exenatide may have a slight effect on blood pressure, its primary action is on glucose metabolism, not blood pressure regulation.
**Option C:** Exenatide is contraindicated in patients with a history of pancreatitis. This is incorrect because exenatide is actually contraindicated in patients with a history of pancreatitis or pancreatic cancer, but not necessarily a history of pancreatitis.
**Option D:** Exenatide is administered via subcutaneous injection once daily. This is incorrect because exenatide is typically administered via subcutaneous injection twice daily.
**Clinical Pearl / High-Yield Fact**
It's essential to note that GLP-1 receptor agonists like exenatide can cause thyroid C-cell tumors in rodents, and there is a potential risk of thyroid tumors in humans. However, the clinical significance of this finding is still being evaluated.
**Correct Answer: D. Exenatide is administered via subcutaneous injection once daily.**