FDA approves Symlin (pramlintide), the amylin analog

In March 2005, the Food and Drug Administration approved Symlin, the brand name for pramlintide acetate, an injectable amylin analog developed for people with type 1 or type 2 diabetes ^[1]. The drug's labeling states it is indicated for patients who use mealtime insulin and have not reached their glucose goals despite optimal insulin therapy ^[1]. It was marketed by AstraZeneca Pharmaceuticals LP ^[1].

Symlin's label carries a boxed warning, the FDA's strongest safety alert, for severe hypoglycemia ^[1]. The warning notes that using Symlin with insulin raises the risk of severe low blood sugar, particularly for people with type 1 diabetes ^[1]. To manage this risk, the label instructs that mealtime insulin doses be cut by 50% when Symlin is started, along with frequent blood glucose monitoring and individualized insulin adjustments afterward ^[1].

Dosing differs by diabetes type. For type 1 diabetes, the starting dose is 15 micrograms injected before major meals, increased in 15-microgram steps up to a maximum of 30 or 60 micrograms, with a step-down to 30 micrograms if the higher dose is not tolerated ^[1]. For type 2 diabetes, dosing starts at 60 micrograms before major meals and can be increased to 120 micrograms as tolerated ^[1]. The label advises waiting at least three days between dose increases to reduce nausea ^[1]. Symlin is not to be mixed with insulin in the same injection; the two must be given as separate shots ^[1]. The drug is also contraindicated for people with a prior serious hypersensitivity reaction to it, hypoglycemia unawareness, or confirmed gastroparesis ^[1].

Because Symlin slows gastric emptying, the label recommends that other oral medications be taken at least one hour before or two hours after a dose if their timing or absorption is critical ^[1]. The most common side effects reported in clinical trials, occurring in 5% or more of patients and more often than with placebo, were nausea, vomiting, loss of appetite, and headache ^[1]. The drug is available in two pen-injector devices, SymlinPen 60 and SymlinPen 120, each delivering different dose ranges ^[1].

Why it matters for patients

Symlin represented a different approach to diabetes management than insulin alone, targeting a hormone called amylin that is also deficient in people with diabetes ^[1]. But the practical demands of starting the drug were significant: the required 50% cut in mealtime insulin, the boxed warning on severe hypoglycemia, and the need for separate injections and careful timing around meals and other medications made it a complex addition to an insulin regimen ^[1]. For patients managing type 1 diabetes especially, the label's warning that hypoglycemia risk is heightened means the drug required close coordination with a prescriber during the initiation and titration phases ^[1].

The source material reviewed for this article, the current FDA-approved drug label, does not include sales figures or market adoption data, so the extent of Symlin's use in the years after approval is not addressed in that document. Readers interested in how widely the drug was ultimately prescribed would need to consult separate market or sales records not covered here.

What happens next

The label reviewed here was last revised in December 2019, indicating the product has remained on the market with updated prescribing information ^[1]. No further regulatory changes or discontinuation dates are noted in the source material.