Follistatin: Reference Overview and Reconstitution Notes

July 9, 2026

Follistatin

What it is

Follistatin is a naturally occurring secreted glycoprotein that binds and neutralizes members of the TGF-beta superfamily, most notably myostatin (GDF-8) and activin. Research supplies are usually offered as the lyophilized recombinant variant Follistatin-344 (FST-344).

Research context and categorization

Follistatin is generally grouped under muscle and metabolic regulation research, and is frequently described alongside myostatin inhibitors and myostatin-binding proteins. Because it binds and dampens myostatin signaling, it is commonly discussed in relation to skeletal muscle mass and body composition in preclinical models. In laboratory and animal work it has been investigated for muscle atrophy and muscular dystrophy models, and it is studied in the context of activin binding and tissue signaling pathways.

These uses are investigational. Follistatin is not an approved therapeutic, human data is limited, and the effects described in research settings are not confirmed or approved benefits. It should be treated strictly as a research reference material.

Status

Regulatory status: Research-only, not FDA-approved. There are no approved pharmaceutical follistatin formulations.
Sport status: Prohibited under the WADA Prohibited List. It falls under S4, Hormone and Metabolic Modulators, in the category covering agents that reduce or ablate myostatin activity and myostatin-binding proteins, where follistatin is named explicitly.

Reconstitution notes (general)

Lyophilized peptides are prepared by adding bacteriostatic water to the vial. The resulting concentration follows a simple relationship: concentration equals the milligrams of peptide in the vial divided by the millilitres of bacteriostatic water added. For example, 1 mg of powder plus 1 mL of water gives 1 mg/mL, while the same 1 mg with 0.5 mL gives 2 mg/mL. A reconstitution calculator is available at our reconstitution and blend calculators.

Dilution and handling notes (compound-specific)

Follistatin-344 is a reconstituted lyophilized powder, most often supplied in 1 mg vials. Typical reconstitution uses roughly 0.5 mL to 1 mL of bacteriostatic water per 1 mg vial, which yields a working concentration in the 1 mg/mL to 2 mg/mL range. Lower water volumes give a more concentrated solution and less liquid to measure, while more water makes fine measurement easier.

As a glycoprotein it is more delicate than short synthetic peptides. Direct the water stream against the vial wall rather than onto the powder, then swirl gently and let it stand for several minutes to fully dissolve. Do not shake, because vigorous agitation can foam the solution and stress the protein. A properly reconstituted vial should be clear and colorless. If it stays cloudy, shows persistent particulates, or will not clear after gentle swirling, treat that as a quality or handling problem rather than forcing it into solution.

Handling and storage

Store the reconstituted vial refrigerated at 2 to 8 C and keep it out of direct light. Wipe the stopper with an alcohol swab before each access, and label the vial with the mix date so the age of the solution is known. A refrigerated reconstituted solution is generally used within about a 4-week window, and unopened lyophilized powder keeps longer when frozen. Avoid repeated freeze-thaw cycles. Discard the vial if the contents become cloudy, discolored, or develop floaters.

Tools and supplies

For laboratory and research reference only. Educational content, not medical, dosing, injection, or therapeutic guidance, and not intended for human or animal use. Any research uses described are investigational and not confirmed or approved benefits. Confirm anything involving health with a licensed professional. References linked above.