Injectable peptides are short chain amino acids that offer varied benefits for health and wellness beyond those already naturally occurring in the body. “Research-grade” versions bought over the counter and via questionable sites online aim to promote skin elasticity, muscle recovery and growth, faster wound healing and much more. Interest in these peptides seems to be growing, fueled by podcast appearances by leading health officials, social media influencers and general consumers, partly thanks to popular oral GLP-1 weight loss drugs (some of which became FDA approved in December 2025).
Although they are not approved by the Food and Drug Administration, proponents of these drugs point to the success of the few peptide medications that are FDA-approved, including oxytocin (as Pitocin used for some patients during labor and following childbirth) and insulin (for type 1 and type 2 diabetes), and say that sale of these peptides would be safer than currently available on the virtually entirely unregulated gray market.
Now the FDA may take seven of 19 synthetic peptides off the Category 2 Bulk Substances List — which denotes formulations that are currently believed by the agency to carry important safety risks. The move would lift the ban on access to compounding pharmacies and allow them to produce and sell these peptides—even without the substances gaining an FDA-approved label.
The Drexel News Blog checked in with Paul W. Brandt-Rauf, ScD, MD, DrPH, a distinguished university professor and dean of the School of Biomedical Engineering, Science and Health Systems, who has studied peptide therapies for treatment and prevention of cancer, to ask him about the potential for peptides and possible safety risks.
What are peptides and how do they work?
Peptides are polymers made up of short sequences of amino acids, i.e., small proteins. Many peptides are signaling molecules that are secreted by one cell to carry a message to another cell. They usually have a specific shape that allows them to attach to specific receptors in the target cells to elicit a specific physiologic response. Many pharmacologic peptides are variants of natural peptides that have been modified to produce more desirable effects and to be able to be patented.
What are some possible medical and nonmedical uses for peptides?
Peptides can be used to treat various diseases, e.g., when the endogenous peptide is not functioning (think insulin for diabetes, linaclotide for IBS, thymosin for wound healing, carfilzomib for multiple myeloma, tesamorelin for lipodystrophy, etc.). They have also been promoted for cosmetic purposes (e.g., collagen skin creams, creatine peptides for muscle growth) with little evidence.
Peptides have been around for more than a hundred years. Why does there seem like so much excitement around peptides lately?
Manufacturing peptides has become easier/cheaper (e.g., when insulin was first isolated in the 1920s from animal pancreases, it took a lot of animals and a lot of time to just get one dose; with genetic engineering in the 1980s it became possible to clone large amounts of insulin quickly and cheaply). Now new peptides have been discovered that have multiple beneficial effects with less side effects (e.g., GLP-1) which was originally intended for diabetes therapy but, unlike insulin, was also found to treat obesity and potentially many other common diseases.
There may soon be a reversal of a 2023 FDA decision that deemed 19 peptides as too unsafe for compounding pharmacies to sell. How does the FDA currently handle review of peptides?
Peptides are currently considered by FDA as a restricted Category 2 compound meaning they should not be used in compound drugs due to potential risks. A problem is that different pharmacies may compound the peptides differently with unknown effects both on the intended therapy and the unknown side effects. But because of the huge and growing demand for the peptides, pharmaceutical companies cannot keep up with the demand at this time.
What are you most concerned about when it comes to safety issues?
Unintended side effects, acutely and unknown long-term risks. Large-scale clinical trials would help. How can the grey market for these peptides be managed? People are seeking any sources of the peptides that they can find, e.g., from online ads, without being certain exactly what they are getting.
Reporters interested in talking with Brandt-Rauf should contact Greg Richter, an assistant director of media relations, at 215-895-2614 or gdr33@drexel.edu.
