Symlin, an amylin analog for diabetes, was approved in 2005 with a severe hypoglycemia warning

The FDA approved Symlin (pramlintide acetate) in 2005 for people with type 1 or type 2 diabetes who use mealtime insulin and have not reached their desired blood sugar control despite optimal insulin therapy ^[1]. The approval carried a boxed warning, the FDA's most serious safety alert, for severe hypoglycemia ^[1].

That warning states that using Symlin with insulin "has been associated with an increased risk of severe hypoglycemia, particularly in patients with type 1 diabetes," and that the risk may be reduced by appropriate patient selection, careful patient instruction and insulin dose reduction ^[1]. When treatment starts, the label directs a 50% reduction in the mealtime insulin dose, frequent glucose monitoring, and individualized insulin adjustments afterward ^[1].

Dosing instructions differ by diabetes type. For type 1 diabetes, the label specifies starting at 15 micrograms injected under the skin before major meals, increasing in 15-microgram steps to a maximum premeal dose of 30 or 60 micrograms, with a step down to 30 micrograms if a higher dose is not tolerated ^[1]. For type 2 diabetes, it specifies starting at 60 micrograms before major meals and increasing to 120 micrograms as tolerated ^[1]. At least three days should pass between dose increases to minimize nausea ^[1].

The label lists three contraindications: a prior serious allergic reaction to Symlin or its ingredients, hypoglycemia unawareness, and confirmed gastroparesis, a condition in which the stomach empties too slowly ^[1]. Symlin must never be mixed with insulin in the same injection, because mixing can change how the body handles both products; they are given as separate injections ^[1]. A SymlinPen should never be shared between patients, even if the needle is changed ^[1]. Because Symlin slows gastric emptying, oral medicines for which rapid onset or a specific blood level matters should be taken at least one hour before or two hours after a Symlin dose ^[1].

The most common side effects in trials, seen in at least 5% of patients and more often than with placebo, were nausea, vomiting, anorexia and headache ^[1]. Symlin is sold as two disposable pen-injectors, both at 1000 micrograms per milliliter: the SymlinPen 60 (1.5 mL), which delivers 15, 30, 45 or 60 micrograms, and the SymlinPen 120 (2.7 mL), which delivers 60 or 120 micrograms ^[1]. The product is packaged by AstraZeneca Pharmaceuticals LP ^[1]. The prescribing information was last revised in December 2019, and the DailyMed entry was updated December 18, 2019 ^[1].

Why it matters for patients

Symlin is not a GLP-1 medication. It is an amylin analog ^[1], a different class from semaglutide (sold as Ozempic, Wegovy and Rybelsus), tirzepatide (Mounjaro and Zepbound) and orforglipron (Foundayo). The labeling does not compare Symlin with any of those drugs, so it does not show how it stacks up against them.

People who use mealtime insulin are the only group the label covers ^[1]. For them, the boxed warning is the central practical fact: adding Symlin means changing insulin doses and checking glucose more often, steps the label links to lowering hypoglycemia risk ^[1]. People with hypoglycemia unawareness or confirmed gastroparesis fall outside the approved use ^[1].

Nausea, vomiting and loss of appetite are common, and the requirement of at least three days between dose increases is intended to limit nausea ^[1]. A separate injection from insulin, plus the timing rule for certain oral medicines, adds steps to daily diabetes care ^[1].

How widely pramlintide is prescribed in the U.S. today is not stated in the prescribing information, and the label reports no sales or patient numbers ^[1].

What happens next

The current prescribing information dates to December 2019 ^[1]. The labeling describes no further studies, label changes or new formulations ^[1].