A peptide drug innovator has said the entire class of peptide medicines needs clearer scientific and regulatory definitions, as use of both approved and unapproved peptides continues to expand in the US.
The comments come amid rising demand for peptide-based drugs, especially GLP-1 medicines used for diabetes and weight loss, which have become some of the best-selling treatments globally through companies such as Eli Lilly and Novo Nordisk.
Growing use beyond approved medicines
Peptides are short chains of amino acids used to influence biological processes in the body. Some, like insulin and GLP-1 receptor agonists (GLP-1RAs), are fully approved and widely prescribed.
But many other peptides are being used outside approved medical channels. These are often promoted in online wellness, fitness, and “biohacking” communities for claims related to recovery, gut health, immune support, and appearance.
Several of these compounds have limited human clinical testing, but are still being sold through online vendors or compounded in pharmacies under varying regulations.
FDA pressure and compounding debate
US regulators have recently faced pressure over how to handle growing demand for peptides. An FDA advisory panel has voted to allow certain peptides to be produced in compounding pharmacies without full clinical trials, a move aimed at reducing unsafe black-market supply.
However, the FDA has not granted full approval to most of these compounds, and safety and effectiveness data remain limited for many of them.
The issue has also drawn political attention, with US Health Secretary Robert F Kennedy Jr. expressing support for broader access to peptide-based treatments.
Industry calls for clearer classification
In an interview, Karsten Eastman, CEO of Sethera Therapeutics, said peptides are becoming more complex and harder to define under current regulatory categories.
He said new engineering methods, including “macrocyclic” and “poly-macrocyclic” peptides, are creating larger and more stable drug structures that may blur the line between small molecules and biologics.
According to Eastman, this raises questions about how regulators classify and approve these therapies, since different categories follow different approval pathways.
He also said that while innovation is accelerating, most of these newer peptide formats still require standard safety testing, including toxicology studies and early clinical trials.
Safety concerns remain
Eastman also noted that growing public interest has led to increased use of unapproved peptides, often without medical supervision.
Experts warn that products sold outside regulated systems may carry risks such as contamination, incorrect dosing, and unknown long-term effects.
Outlook
Sethera Therapeutics and other biotech firms are continuing to develop more advanced peptide designs, including longer-acting GLP-1-based treatments that could reduce injection frequency.
However, researchers and regulators say clearer classification rules and stronger public education may be needed as demand continues to grow faster than regulation.