Amylin Physiology

Amylin is co-located with insulin in secretory granules and co-secreted with insulin by pancreatic beta cells in response to food intake. Amylin and insulin show similar fasting and postprandial patterns in healthy individuals (Figure 1).

Figure 1: Secretion Profile of Amylin and Insulin in Healthy Adults

Amylin affects the rate of postprandial glucose appearance through a variety of mechanisms. Amylin slows gastric emptying (i.e., the rate at which food is released from the stomach to the small intestine) without altering the overall absorption of nutrients. In addition, amylin suppresses glucagon secretion (not normalized by insulin alone), which leads to suppression of endogenous glucose output from the liver. Amylin also regulates food intake due to centrally-mediated modulation of appetite.

In patients with insulin-using type 2 or type 1 diabetes, the pancreatic beta cells are dysfunctional or damaged, resulting in reduced secretion of both insulin and amylin in response to food.

Mechanism of Action

SYMLIN, by acting as an amylinomimetic agent, has the following effects: 1) modulation of gastric emptying; 2) prevention of the postprandial rise in plasma glucagon; and 3) satiety leading to decreased caloric intake and potential weight loss.

Gastric Emptying. The gastric-emptying rate is an important determinant of the postprandial rise in plasma glucose. SYMLIN slows the rate at which food is released from the stomach to the small intestine following a meal and, thus, it reduces the initial postprandial increase in plasma glucose. This effect lasts for approximately 3 hours following SYMLIN administration. SYMLIN does not alter the net absorption of ingested carbohydrate or other nutrients.

Postprandial Glucagon Secretion. In patients with diabetes, glucagon concentrations are abnormally elevated during the postprandial period, contributing to hyperglycemia. SYMLIN has been shown to decrease postprandial glucagon concentrations in insulin-using patients with diabetes.

Satiety. SYMLIN administered prior to a meal has been shown to reduce total caloric intake. This effect appears to be independent of the nausea that can accompany SYMLIN treatment.

Pharmacokinetics

Absorption. The absolute bioavailability of a single SC dose of SYMLIN is approximately 30 to 40%. Subcutaneous administration of different doses of SYMLIN into the abdominal area or thigh of healthy subjects resulted in dose-proportionate maximum plasma concentrations (Cmax) and overall exposure (expressed as area under the plasma concentration curve or (AUC)) (Table 1).

Table 1: Mean Pharmacokinetic Parameters Following Administration of Single SC Doses of SYMLIN

Injection of SYMLIN into the arm showed higher exposure with greater variability, compared with exposure after injection of SYMLIN into the abdominal area or thigh.

Bookmark this page: