Side-by-side · Research reference

Follistatin-344vsTeriparatide

Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.

AHuman-MechanisticHUMAN-REVIEWED4/58 cited

BFDA-ApprovedHUMAN-REVIEWED10/62 cited

Follistatin-344

Myostatin/Activin Antagonist · Research Use

15–25%FST/MSTN ratio ↑

344 AACirculating isoform

ResearchPhase status

Research · No approved protocol

Teriparatide

PTH (1-34) Fragment · FDA-Approved

20 mcgDaily dose

12-18 moAnabolic windowFerrari 2026

SQRoute

SQ · Thigh/Abdomen · Once Daily

01Mechanism of Action

Parameter

Follistatin-344

Teriparatide

Primary target

Myostatin (MSTN/GDF-8) and Activin A

Parathyroid hormone 1 receptor (PTH1R) on osteoblastsXue 2026

Pathway

FST-344 binds MSTN/Activin → prevents ActRIIB receptor engagement → disinhibits muscle anabolism

PTH1R activation → cAMP/PKA signaling → osteoblast differentiation and activity

Downstream effect

Elevated follistatin/myostatin ratio, increased muscle protein synthesis, attenuated muscle atrophy signalingJeong 2026

Stimulates osteoblast formation and bone matrix deposition; increases bone mineral density at trabecular and cortical sites

Feedback intact?

Yes — indirect antagonist, preserves endogenous regulation

Yes — intermittent dosing preserves anabolic effect; continuous exposure causes catabolic bone resorption

Origin

Endogenous glycoprotein, 344-AA isoform lacking heparin-binding domain (vs FST-315)

Recombinant 34-amino-acid N-terminal fragment of 84-amino-acid human PTH

Antibody development

Not documented in available trials (endogenous protein)

—

02Dosage Protocols

Parameter

Follistatin-344

Teriparatide

Clinical protocol

None — no approved dosing regimen

Follistatin-344 measured as endogenous biomarker, not administered exogenously in cited trials.

—

Research context

Endogenous modulation via exercise + nutrition

Resistance training + EAA intake elevated FST/MSTN ratio by 15–25% in 12-week RCT (older women).

—

Evidence basis

Human observational / biomarker studies

RCT / FDA-approved

Half-life

Not established

Circulating isoform; lacks tissue-binding domain of FST-315.

—

Standard dose (osteoporosis)

—

20 mcg / day

FDA-approved regimen for severe osteoporosis.

Frequency

—

Once daily

Intermittent administration preserves anabolic effect.

Maximum duration

—

24 months lifetime

Anabolic effect wanes after 12-18 months; FDA recommends max 2-year cumulative exposure.

Hypoparathyroidism dose

—

20 mcg / day

Used off-label for chronic hypoparathyroidism.

Pelvic fragility fractures

—

20 mcg / day × 8-12 weeks

Accelerates fracture healing; reduces time to union.Crooks 2026

Route

—

Subcutaneous (thigh or abdomen)

Timing

—

Morning or evening (flexible)

Storage

—

Refrigerate 2-8 °C; pen device stable at room temp for 28 days after first use

Pharmacogenetics

—

ALDH2 polymorphisms may influence BMD responseObara 2026

ALDH2*2 variant carriers show altered PTH receptor expression.Obara 2026

03Metabolic / Fat Loss Evidence

Parameter

Follistatin-344

Teriparatide

Primary target

Muscle mass preservation, not direct lipolysis

—

Indirect fat effect

Increased lean mass → elevated resting metabolic rate

Not primary mechanism. Muscle-sparing during deficit.

—

Clinical evidence

Lorcaserin trial (6 mo) showed no MAFI axis changes during fat lossRamirez-Cisneros 2026

Suggests follistatin not primary driver of fat loss in weight-reduction interventions.

—

GLP-1RA studies

Liraglutide (35 days) — no significant MAFI axis modulation despite fat/lean changes

—

Fat loss application

—

None — teriparatide is a bone anabolic agent without direct lipolytic activity

04Side Effects & Safety

Parameter

Follistatin-344

Teriparatide

Clinical safety data

None — no human exogenous administration trials in literature

—

Theoretical risks

Excessive myostatin inhibition → muscle overgrowth, impaired glucose tolerance

Based on myostatin-null animal models and clinical myostatin inhibitor trials.

—

Endogenous elevation (exercise)

No adverse effects reported in 12-week resistance + EAA trials

—

Cancer risk (theoretical)

Myostatin inhibition may promote tumor growth in malignancy (preclinical data)

—

Regulatory status

Not approved for human use — research peptide only

—

Hypercalcemia

—

Transient serum calcium elevation 4-6 hours post-injection

Monitor serum calcium; usually asymptomatic.

Orthostatic hypotension

—

Dizziness, lightheadedness within hours of injection

Nausea

—

Common, usually mild and transient

Leg cramps / Arthralgia

—

Musculoskeletal pain reported in clinical trials

Hypercalciuria

—

Increased urinary calcium excretion; monitor for nephrolithiasis risk

Osteosarcoma (black box warning)

—

Rat studies showed dose-dependent osteosarcoma; not observed in humans to date; contraindicated in Paget's disease, skeletal malignancy, prior radiation

Injection site reaction

—

Erythema, bruising, pain (uncommon)

Absolute Contraindications

Follistatin-344

·Active malignancy
·No approved protocol — research use only

Teriparatide

·Paget's disease of bone (increased baseline osteosarcoma risk)
·Unexplained elevated alkaline phosphatase
·Prior skeletal radiation therapy
·Skeletal malignancies or bone metastases
·Hypercalcemic disorders (primary hyperparathyroidism)
·Pregnancy / lactation

Relative Contraindications

Follistatin-344

·Insulin resistance / Type 2 diabetes (monitor glucose)
·Pregnancy / lactation (unknown safety profile)

Teriparatide

·Active or recent nephrolithiasis
·Severe renal impairment (CKD G4-G5)
·Hypercalciuria without adequate monitoring

05Administration Protocol

Parameter

Follistatin-344

Teriparatide

1. Regulatory status

Follistatin-344 is not approved for human administration. All cited studies measure endogenous serum follistatin as a biomarker, not as an exogenous therapeutic agent.

Teriparatide is supplied in pre-filled pen injectors (Forteo pen). Store refrigerated at 2-8 °C until first use. After first injection, pen may be kept at room temperature for up to 28 days. Do not freeze.

2. Endogenous modulation

Resistance exercise combined with essential amino acid (EAA) supplementation elevated the follistatin/myostatin ratio by 15–25% in 12-week randomized trials. Protein intake (1.2–1.5 g/kg/day) synergizes with training to upregulate endogenous follistatin.

Subcutaneous injection into thigh or lower abdomen. Rotate sites daily to avoid lipodystrophy. Avoid areas with scars, bruises, or active skin conditions.

3. Measurement context

Serum follistatin and follistatin/myostatin ratio are used diagnostically in sarcopenia screening and as biomarkers of muscle anabolic balance in clinical trials.

Once daily, at approximately the same time each day. Morning or evening administration is acceptable. Take while sitting or lying down to minimize orthostatic hypotension risk.

4. Research consideration

Gene therapy and recombinant follistatin delivery are under preclinical investigation for muscular dystrophy and sarcopenia. No human safety or efficacy data for exogenous FST-344 administration.

Clean injection site with alcohol swab. Pinch skin, insert needle at 90° angle, and inject full dose (20 mcg). Hold for 5 seconds before withdrawing needle. Do not rub injection site.

5. Monitoring

—

Baseline and periodic monitoring of serum calcium, urinary calcium, serum PTH (if hypoparathyroidism), and bone mineral density (DXA scan). Monitor for hypercalcemia 4-6 hours post-dose if symptomatic.

6. Calcium and vitamin D supplementation

—

Ensure adequate calcium (1000-1200 mg/day) and vitamin D (800-1000 IU/day) intake unless contraindicated by hypercalcemia or hypercalciuria.

06Stack Synergy

Follistatin-344

+ BPC-157

Multi-pathway

View BPC-157 →

Follistatin-344 (myostatin antagonist) and BPC-157 (tissue repair peptide) address complementary pathways in muscle recovery. FST-344 promotes muscle protein synthesis by disinhibiting myostatin signaling, while BPC-157 accelerates healing of tendons, ligaments, and microtears via angiogenesis and collagen synthesis. Combined, they may support both hypertrophy and structural repair during high-volume training or injury recovery.

Follistatin-344: No approved protocol — endogenous modulation via resistance exercise + EAA
BPC-157: 250–500 mcg SQ · twice daily · near injury site or systemic
Duration: 4–8 weeks
Primary benefit: Muscle hypertrophy + accelerated soft tissue repair

+ TB-500

Moderate

View TB-500 →

TB-500 (thymosin beta-4 fragment) promotes cell migration, angiogenesis, and anti-inflammatory signaling in muscle and connective tissue. Follistatin-344's anabolic signaling may synergize with TB-500's regenerative effects during muscle damage or overtraining, particularly in older adults where both myostatin inhibition and tissue repair are rate-limiting.

Follistatin-344: Endogenous upregulation (resistance training + protein)
TB-500: 2–5 mg SQ · twice weekly · loading phase 4 weeks, then maintenance
Frequency: Twice weekly TB-500, daily training stimulus for FST
Primary benefit: Enhanced recovery, reduced inflammation, muscle growth support

Teriparatide

— no documented stacks