Is GYM329 legal in the United States?

The one myostatin antibody now being tested where it matters most: alongside tirzepatide in people with obesity, and for insulin sensitivity in type 2 diabetes. No results yet.

Three anti-myostatin antibodies added lean mass and failed to improve function, all in people with muscular dystrophy or long-standing weakness. GYM329 is the first to be aimed squarely at the population this site's readers belong to, and that makes it the most consequential open question in the field.

Mechanism: An antibody engineered by Chugai and Roche against latent myostatin, the inactive precursor form, rather than the mature active protein. It uses antigen sweeping, an engineering approach that promotes uptake and degradation of the antibody-antigen complex so the target is actively cleared instead of merely blocked.

Regulatory history: Investigational. Not approved for any indication.

Approves prescription drugs by indication and polices unapproved products, including peptides sold online. Compounding pharmacies may prepare some compounds under a prescription when the FDA places them on a permitted bulk-substances category.

The classification above is the The Longevity Archive reading of U.S. Food and Drug Administration listings for GYM329 at the reviewed date, not a legal opinion. Rules change, and importing, prescribing and possessing a compound can each be treated differently. Check the regulator directly before acting on anything here.