MEDICAL DISCLAIMER: Educational research guidelines only. Lyophilized peptides are investigational chemical compounds and are NOT approved for human consumption, diagnosis, or therapy. Consult a licensed physician before any research application.
Follistatin-344 Dosage Chart, Schedule & Reconstitution Protocol
Quickstart Highlights
Follistatin-344 (FS-344) is a recombinant follistatin glycoprotein that neutralizes myostatin (GDF-8) and activin A, two TGF-β ligands that restrain skeletal-muscle growth (PMID 9139826, PMID 11459935). Removing that brake de-represses the Akt/mTOR pathway and satellite-cell proliferation; in mice, follistatin can quadruple muscle mass (PMID 17726519), and AAV-delivered FS344 produced durable muscle and strength gains in primates and early-phase human trials (PMID 20368179, PMID 25322757, PMID 28279643). Crucially, every efficacy study used gene therapy injected into muscle, not exogenous peptide. Community/research protocols nonetheless model subcutaneous injection at roughly 100-200 mcg/day (up to 300 mcg/day) in short cycles, a convention with no controlled human validation. Follistatin-344 is not FDA- or EMA-approved, is WADA-prohibited, and is sold for laboratory research only. The reconstitution and dosing figures here are an educational measurement reference, not medical advice.
Reconstitute: Add 2 mL bacteriostatic water → 0.5 mg/mL concentration.
Typical dose: 100-200 mcg/day SC (research; up to 300 mcg/day)
Easy measuring: At 0.5 mg/mL, 1 unit = 0.01 mL = 0.0050 mg (5 mcg) on a U-100 insulin syringe.
Storage: Lyophilized powder stored frozen at −20 °C and protected from light; reconstituted solution refrigerated at 2-8 °C and used within roughly 2-3 weeks. Follistatin is a fragile protein, so avoid repeated freeze-thaw cycles, heat, and vigorous agitation.
Half-life: Short: exogenous follistatin protein clears within roughly 30 minutes to a few hours via cell-surface heparan-sulfate sequestration and renal clearance; glycosylated FST-315 lasts somewhat longer. Human PK for injected peptide is not well characterized.
Route: Research community models subcutaneous injection; the only human-validated delivery is intramuscular AAV gene therapy. Oral bioavailability is negligible (under 5%).
Status: Not FDA- or EMA-approved; research/educational use only; prohibited in sport by WADA as a myostatin-affecting agent.
About Follistatin-344
Follistatin-344 (FS-344) is a research-grade recombinant follistatin, a glycoprotein that neutralizes myostatin (GDF-8) and activin A to de-repress skeletal-muscle growth [1][2]. The "344" denotes the 344-amino-acid precursor transcript; after the signal peptide is removed, the mature, circulating FST-315 isoform is produced. Importantly, the only human-validated way follistatin has been delivered is intramuscular AAV gene therapy in clinical trials [6][7][8]; the subcutaneous injection figures below are an educational reconstitution and measurement reference, not a clinically proven delivery route, and the dosing reflects community/research convention rather than controlled human data.\n\nThis guide models a 1 mg vial reconstituted with 2 mL of bacteriostatic water, giving 500 mcg/mL, or 5 mcg per insulin-syringe unit, so research doses map cleanly onto a U-100 syringe: 100 mcg = 20 units, 150 mcg = 30 units, 200 mcg = 40 units, and 300 mcg = 60 units. A typical Follistatin-344 dosage discussed in the research community is 100-200 mcg per day, with some sources extending to 300 mcg/day, almost always run in short 2-4 week cycles rather than continuously.\n\nFrequency: Once daily subcutaneously (often in short cycles), based on follistatin's brief circulating half-life. Follistatin-344 is not FDA- or EMA-approved, is prohibited by WADA, and is presented here for educational purposes only.
Quick Protocol Navigation
Reconstitution Instruction & Mixing Step-by-Step
Lyophilized powder must be reconstituted carefully. Agitating peptide chains can shear disulfide bonds and render the peptide biologically inert.
Draw 2 mL of bacteriostatic water into a sterile syringe.
Inject the water slowly down the inner wall of the 1 mg Follistatin-344 vial; do not aim the stream directly at the powder, and never shake, follistatin is a fragile protein that can denature with agitation.
Gently swirl or roll the vial until the solution is completely clear; the result is a 500 mcg/mL concentration, or 5 mcg per insulin-syringe unit.
Store refrigerated at 2-8 °C and draw the prescribed units per dose (100 mcg = 20 units, 150 mcg = 30 units, 200 mcg = 40 units, 300 mcg = 60 units).
Educational note: the only human-validated delivery of follistatin is intramuscular AAV gene therapy in clinical trials, so this subcutaneous reconstitution scheme is a measurement reference only; if modeling the SC route, inject slowly into subcutaneous tissue, rotate sites, and discard the vial after roughly 2-3 weeks.
Interactive Follistatin-344 Syringe Calculator
Currently visualizing the 1 mg vial reconstituted with 2 mL bacteriostatic water. Adjust the target dose to dynamically render syringe units.
Reconstitution Calculation: 1mg dry powder in 2mL water yields 0.50 mg/mL. To evaluate a 250mcg dose, pull to 50.0 units (50 syringe ticks).
U-100 Syringe Representation
Educational reference visual. Assumes standard U-100 insulin syringe where 1.0 mL volume = 100 units.
Titration & Dose Escalation Schedules
| Phase | Dose per injection | Units (per injection) |
|---|---|---|
| Initiation (low dose) | 100 mcg | 20 units (0.20 mL) |
| Standard research dose | 200 mcg | 40 units (0.40 mL) |
| Upper community ceiling | 300 mcg | 60 units (0.60 mL) |
Administration guidelines: Refer to guidelines | 2 mL Reconstitution
Research Supplies Quantity Planner
Scientific mathematical planning of syringes, bacteriostatic water and dry vials needed for extended research blocks using the 1 mg vial.
Peptide Vials (Follistatin-344, 1 mg each):
- checkAt 100-200 mcg/day a 1 mg vial lasts roughly 5-10 days, so an 8-week course models about 6-12 vials.
- check12-week course: approximately 9-17 vials at 100-200 mcg/day.
- check16-week course: approximately 12-23 vials at 100-200 mcg/day.
- checkContinuous daily use is uncommon; most run short 2-4 week cycles, which lowers these totals substantially.
Insulin Syringes (U-100):
- checkOne 0.5 mL U-100 syringe (29-31 G) per daily subcutaneous injection.
- check8 weeks ≈ 56 syringes; 12 weeks ≈ 84; 16 weeks ≈ 112 (round up to 100-count boxes).
- checkKeep spares if dosing is split into twice-daily injections.
- checkNever reuse needles; use a sharps container for disposal.
Bacteriostatic Water (30 mL bottles): Use 2 mL per vial for reconstitution.
- checkEach 1 mg vial requires 2 mL, so a single 30 mL bottle reconstitutes about 15 vials.
- check8-week course ≈ 1 bottle; 12-week ≈ 1-2 bottles; 16-week ≈ 1-2 bottles.
- checkDiscard each reconstituted vial after roughly 2-3 weeks regardless of remaining volume.
Alcohol Swabs:
- checkUse two swabs per injection: one for the vial stopper and one for the skin site.
- check8 weeks ≈ 110+ swabs; 12 weeks ≈ 170+; 16 weeks ≈ 220+.
- checkBuy in 200-count boxes and never reuse a swab.
- checkRotate injection sites (abdomen, thigh, upper arm) to reduce irritation.
Mechanism of Action (MOA)
Follistatin is an autocrine/paracrine glycoprotein that regulates the TGF-β superfamily. The designation "Follistatin-344" (FS-344) refers to the 344-amino-acid precursor encoded by one of the alternatively spliced FST transcripts; after cleavage of its signal peptide it yields the mature 315-residue isoform (FST-315), the predominant circulating form. A second transcript produces the shorter, cell-surface-bound FST-288 isoform. All isoforms share an N-terminal domain plus three follistatin domains and a heparin-binding sequence that governs how tightly the protein anchors to cell-surface heparan-sulfate proteoglycans [5].\n\nMechanistically, follistatin works by sequestering ligands rather than signaling through a receptor of its own. Its primary muscle-relevant target is myostatin (GDF-8), a negative regulator of skeletal-muscle mass; loss of myostatin alone roughly doubles muscle in mice [1]. Two follistatin molecules wrap around the myostatin dimer and bury all four of its receptor-binding epitopes, preventing myostatin from engaging the activin type II receptors (ActRIIA/ActRIIB) [2][5]. Because the activated receptor would normally phosphorylate SMAD2/3 and restrain growth, neutralizing myostatin de-represses the Akt/mTOR protein-synthesis pathway and promotes satellite-cell proliferation. Critically, follistatin also binds activin A, a second ActRII ligand that limits muscle independently of myostatin; this dual blockade is why follistatin overexpression adds muscle beyond what myostatin deletion alone achieves, up to a quadrupling of muscle mass in mice, and why heterozygous loss of follistatin reduces muscle weight [3][4].\n\nTranslational evidence comes from gene therapy, not injected protein. AAV1-delivered FS344 produced large, durable (over 15 months) increases in quadriceps size and strength in macaques with no organ or reproductive-hormone abnormalities [6], and intramuscular rAAV1.CMV.huFollistatin344 improved six-minute-walk distance in early-phase Becker muscular dystrophy and sporadic inclusion body myositis trials [7][8]. The FS-344-to-FS-315 design was chosen specifically to limit interference with the pituitary activin-inhibin (FSH) axis.\n\nPharmacokinetics are the major caveat for the injected-peptide model used by the research community. Follistatin protein has a short systemic residence time: depending on isoform and glycosylation, exogenous follistatin clears within roughly 30 minutes to a few hours, because the heparin-binding sequence sequesters it on cell surfaces and it is filtered renally. Oral bioavailability is negligible (under 5%) due to proteolytic digestion. There is no published controlled pharmacokinetic or efficacy study of subcutaneously injected follistatin protein in humans, so the half-life, bioavailability, and dose-response of the SC route remain poorly defined [6][7][8]. The subcutaneous reconstitution figures on this page are an educational measurement convention, not a validated therapeutic regimen, and Follistatin-344 remains a research compound only.
Clinical Trial Efficacy Highlights
- starMcPherron, Lawler and Lee (1997, Nature) identified myostatin (GDF-8) as a TGF-β family negative regulator of muscle mass; GDF-8 null mice were dramatically larger than wild-type, with individual muscles weighing roughly two to three times more than controls, establishing the target that follistatin neutralizes [1].
- starLee and McPherron (2001, PNAS) demonstrated that the activin-binding protein follistatin inhibits binding of myostatin to the activin type II receptor (ActRIIB) and proposed follistatin, the myostatin propeptide, or related blockers as agents for enhancing muscle growth, the foundational rationale for follistatin as a myostatin inhibitor [2].
- starLee (2007, PLoS One) showed that a skeletal-muscle follistatin transgene combined with a myostatin-null background quadrupled muscle mass in mice (muscle weights increased ~250-350% over wild-type), proving follistatin enlarges muscle beyond myostatin loss alone by also blocking activin signaling [3].
- starLee and colleagues (2010, Molecular Endocrinology) confirmed that follistatin regulates muscle mass by simultaneously antagonizing both myostatin and activin A, and that heterozygous loss of follistatin reduced muscle weights by roughly 15-20%, underscoring the dual-ligand mechanism [4].
- starCash and colleagues (2009, EMBO J) solved the myostatin:follistatin-288 structure, showing two follistatin molecules wrap the myostatin dimer to block all four receptor-binding sites, and that complex formation creates an electropositive surface that enhances heparin binding and accelerates myostatin clearance [5].
- starKota and colleagues (2009, Science Translational Medicine) injected AAV1-FS344 into the quadriceps of cynomolgus macaques and observed pronounced, durable increases in muscle size and strength persisting beyond 15 months, with no abnormal organ morphology, no adverse immune response, and no effect on reproductive hormones [6].
- starMendell and colleagues (2015, Molecular Therapy) ran a phase 1/2a intramuscular follistatin (rAAV1.CMV.FS344) gene-therapy trial in six ambulatory Becker muscular dystrophy patients; the therapy was well tolerated with normal organ and pituitary-gonadal hormone profiles, and several patients improved six-minute-walk distance by up to ~108-125 meters at one year [7].
- starMendell and colleagues (2017, Molecular Therapy) treated six sporadic inclusion body myositis patients with rAAV1.CMV.huFS344; the treated group improved a median +56 meters/year on the six-minute walk versus −25.8 meters/year in untreated controls (p = 0.01), with reduced fibrosis and improved regeneration on biopsy, though all efficacy used intramuscular gene delivery, not injected peptide [8].
Side Effects & Tolerability Profile
Clinical subjects transiently report mild side effects. Slowly escalating the titration dose represents the single most effective intervention to limit side effects.
- warningThere is no established human safety profile for exogenous subcutaneously injected follistatin protein; all human data come from intramuscular AAV gene therapy, so reports about injected FS-344 peptide are anecdotal and unverified, and dose-response and toxicity are essentially unknown [6][7][8].
- warningFollistatin broadly inhibits activin and other TGF-β ligands that regulate the pituitary FSH axis, reproduction, inflammation, wound healing, and tissue homeostasis; the FS-344/FS-315 design was specifically chosen to limit pituitary involvement, and the gene-therapy trials reported no hormonal changes, but systemic inhibition with unregulated material carries theoretical endocrine and reproductive risk [6][7].
- warningRapid, large gains in muscle force can outpace adaptation of tendons, ligaments, and connective tissue, raising a theoretical risk of strain or tendon injury; effects on cardiac muscle from chronic myostatin/activin inhibition are not characterized in humans.
- warningActivin signaling has tumor-suppressor and growth-regulatory roles in some tissues, so broad, sustained inhibition raises a theoretical oncologic and tissue-overgrowth concern that has not been evaluated for the injected-peptide route.
- warningInjection-site reactions (pain, redness, bruising), and infection or sterility risk are possible, compounded by the fact that research-grade peptides are not manufactured to pharmaceutical standards and can vary in purity, identity, and endotoxin content.
- warningFollistatin protein is fragile and orally inactive (under 5% bioavailability) and clears quickly from circulation; improper storage, freeze-thaw cycling, or agitation can denature it, and the brief half-life means the SC dose-response is poorly defined.
- warningOnline claims linking high-dose follistatin to specific harms such as central serous chorioretinopathy circulate widely but are not supported by peer-reviewed human evidence; absence of documented harm reflects absence of controlled study, not proven safety.
- warningRegulatory/research status: Follistatin-344 is NOT approved by the FDA or EMA for any indication, cannot legally be sold as a dietary supplement, is prohibited in sport by WADA as a myostatin-affecting agent, and is sold for laboratory research use only; long-term human safety is unknown.
Subcutaneous Injection Technique
Most research peptides require subcutaneous injection into fatty tissue. Never inject directly into a blood vessel or deep muscle tissue unless clinically detailed.
1. Site Selection
Common locations include the abdomen (2 inches from navel), outer upper arms, or thighs.
2. Sanitization
Thoroughly clean the selected site, stopper and vial top using 70% isopropyl alcohol prep swabs.
3. Angle & Push
Pinch the skin and insert the needle at a 45 to 90-degree angle. Depress plunger smoothly.
4. Site Rotation
Rotate injection sites continuously to avoid lipodystrophy or tissue scarring.
Frequently Asked Questions
What is the typical Follistatin-344 dosage?expand_more
In research and community protocols the most commonly cited Follistatin-344 dosage is 100-200 mcg per day subcutaneously, with some sources extending to about 300 mcg/day, almost always run in short cycles (often 2-4 weeks on, then off) rather than continuously. These figures are extrapolated from animal and gene-therapy work and anecdotal use, not from controlled human trials of injected follistatin protein, so they should be treated as an educational reference only, not a validated or recommended dose.
Is Follistatin-344 FDA approved?expand_more
No. Follistatin-344 is not approved by the FDA or the EMA for any indication. It is not a dietary supplement and cannot be legally marketed as one. The only follistatin therapeutics studied in humans were AAV gene-therapy investigational products in early-phase muscular dystrophy and myositis trials, which are not approved drugs. Follistatin-344 sold as a peptide is a research-use-only chemical and is also prohibited in sport by WADA as a myostatin-affecting agent.
How do you reconstitute Follistatin-344?expand_more
For the 1 mg vial modeled here, draw 2 mL of bacteriostatic water and inject it slowly down the inner wall of the vial, then swirl gently until clear. Never shake, follistatin is a fragile protein. This yields 500 mcg/mL, or 5 mcg per insulin-syringe unit, so 100 mcg = 20 units, 150 mcg = 30 units, 200 mcg = 40 units, and 300 mcg = 60 units. Store refrigerated at 2-8 °C and use within about 2-3 weeks.
What is the half-life of Follistatin-344?expand_more
Follistatin protein has a short circulating half-life. Depending on isoform and glycosylation, exogenous follistatin clears within roughly 30 minutes to a few hours, because its heparin-binding sequence sequesters it on cell surfaces and it is also filtered renally; the cell-surface FS-288 form clears fastest, while glycosylated FST-315 lasts somewhat longer. There is no published controlled pharmacokinetic study of subcutaneously injected follistatin in humans, so the SC half-life is not well characterized.
Can Follistatin-344 be stacked with other research compounds?expand_more
Some in the research community combine follistatin with growth-hormone secretagogues or other muscle-oriented peptides, but there are no human safety, interaction, or efficacy data for any such combination, and follistatin itself has never been validated as an injected peptide in controlled trials. Stacking unregulated research chemicals compounds the unknowns around purity, dosing, and adverse effects. This information is educational only and is not a recommendation to combine compounds.
Related Guides & Tools
Step-by-step references for reconstituting, measuring, and storing Follistatin-344, plus the universal dosing calculator.
Academic References & Study Citations
McPherron AC, Lawler AM, Lee SJ. Regulation of skeletal muscle mass in mice by a new TGF-beta superfamily member. Nature. 1997;387(6628):83-90. View Scientific Paper →
Lee SJ, McPherron AC. Regulation of myostatin activity and muscle growth. Proc Natl Acad Sci U S A. 2001;98(16):9306-9311. View Scientific Paper →
Lee SJ. Quadrupling muscle mass in mice by targeting TGF-β signaling pathways. PLoS One. 2007;2(8):e789. View Scientific Paper →
Lee SJ, Lee YS, Zimmers TA, et al. Regulation of muscle mass by follistatin and activins. Mol Endocrinol. 2010;24(10):1998-2008. View Scientific Paper →
Cash JN, Rejon CA, McPherron AC, Bernard DJ, Thompson TB. The structure of myostatin:follistatin 288: insights into receptor utilization and heparin binding. EMBO J. 2009;28(17):2662-2676. View Scientific Paper →
Kota J, Handy CR, Haidet AM, et al. Follistatin gene delivery enhances muscle growth and strength in nonhuman primates. Sci Transl Med. 2009;1(6):6ra15. View Scientific Paper →
Mendell JR, Sahenk Z, Malik V, et al. A phase 1/2a follistatin gene therapy trial for Becker muscular dystrophy. Mol Ther. 2015;23(1):192-201. View Scientific Paper →
Mendell JR, Sahenk Z, Al-Zaidy S, et al. Follistatin gene therapy for sporadic inclusion body myositis improves functional outcomes. Mol Ther. 2017;25(4):870-879. View Scientific Paper →
ClinicalTrials.gov. Clinical Intramuscular Gene Transfer of rAAV1.CMV.huFollistatin344 Trial to Patients With Duchenne Muscular Dystrophy. Identifier NCT02354781. View Scientific Paper →