Side-by-side · Research reference

HGH 191AAvsTB-500

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

AFDA-ApprovedHUMAN-REVIEWED0/75 cited

BPhase 2HUMAN-REVIEWED8/46 cited

HGH 191AA

Recombinant hGH · FDA-Approved

0.024–0.034 mg/kg/dayPediatric GHD dose

2–4 hoursPlasma half-life

191 AASequence length

SQ · Daily · Evening preferred

TB-500

Thymosin β4 fragment · Healing

2 mgPer doseGoldstein 2012

Phase 2Evidence levelGoldstein 2012

~2 hrHalf-life

SQ or IM · Multiple sites · 2–3×/week

01Mechanism of Action

Parameter

HGH 191AA

TB-500

Primary target

Growth hormone receptor (GHR) — JAK2/STAT5 pathway

G-actin (sequestering) + cell-surface integrinsGoldstein 2012

Pathway

GHR activation → JAK2/STAT5 → liver IGF-1 synthesis + direct metabolic effects

Actin remodelling → cell migration; integrin-linked signaling → angiogenesis; anti-inflammatory cytokine modulationGoldstein 2012 Malinda 1999

Downstream effect

Linear growth, lipolysis, protein synthesis, nitrogen retention, carbohydrate metabolism modulation

Accelerated wound healing, endothelial migration, hair follicle regeneration, cardiac repair (preclinical)Goldstein 2012

Feedback intact?

No — exogenous GH bypasses hypothalamic-pituitary axis, suppresses endogenous pulsatility

Endogenous protein at baseline; supplementation amplifies

Origin

Recombinant DNA technology — 191 AA, identical to pituitary hGH, no methionyl residue

17-AA active fragment of endogenous 43-AA thymosin β4 (TMSB4X gene)Goldstein 2012

Antibody development

Rare — <2% develop binding antibodies, typically non-neutralizing

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02Dosage Protocols

Parameter

HGH 191AA

TB-500

Pediatric GHD

0.024–0.034 mg/kg/day SQ

6–7× per week dosing typical. Brand-specific ranges.

—

Adult GHD

0.004–0.016 mg/kg/day SQ

Start low, titrate based on IGF-1 levels.

—

Turner syndrome

0.045–0.050 mg/kg/day SQ

—

Idiopathic short stature

0.037 mg/kg/day SQ

—

AIDS wasting

0.1 mg/kg/day SQ (high-dose)

Short-term indication. Monitor glucose.

—

Frequency

Once daily, typically evening

Evening administration mimics physiological GH pulse.

2× per week (loading); then 1× per week (maintenance)

Evidence basis

FDA-approved / decades of RCT data

Animal-strong + Phase 2 dermal/ocular trialsGoldstein 2012

Monitoring

IGF-1, glucose, thyroid function, bone age (children)

—

Duration

Years (children until epiphyseal closure); indefinite (adult GHD)

4–8 weeks loading; longer maintenance for chronic injury

Standard dose

—

2 mg per injectionGoldstein 2012

Anecdotal community range; clinical Phase 2 trials used 70–840 mcg/kg IV.

Lower / starter dose

—

1 mg per injection

Reconstitution

—

Bacteriostatic water, 1–2 mL per 5 mg vial

Timing

—

Evening or pre-rest preferred (anecdotal)

Half-life

—

~2 hours (estimated; tissue uptake longer)

03Metabolic / Fat Loss Evidence

Parameter

HGH 191AA

TB-500

Primary fat target

Visceral and subcutaneous adipose tissue

—

Mechanism

Lipolysis via hormone-sensitive lipase activation, FFA oxidation

—

Effect on lean mass

Significant lean mass increase (protein synthesis, nitrogen retention)

—

Insulin sensitivity

Acute insulin resistance (anti-insulin effect); chronic neutral-to-improved via fat loss

—

IGF-1 elevation

Dose-dependent, significant — primary anabolic mediator

—

Glucose metabolism

Hyperglycemia risk, especially high doses (AIDS wasting)

—

Body composition

↓ fat mass, ↑ lean mass, ↑ bone mineral density (children)

—

Clinical context

FDA-approved for AIDS wasting (cachexia). Off-label use for body recomposition lacks long-term safety data.

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04Side Effects & Safety

Parameter

HGH 191AA

TB-500

Injection site reaction

Lipohypertrophy, lipoatrophy, erythema (rotate sites)

Mild erythema, transient pain

Fluid retention / Edema

Peripheral edema, arthralgia, carpal tunnel syndrome (dose-dependent)

—

Glucose intolerance

Hyperglycemia, new-onset diabetes (anti-insulin effect)

—

Intracranial hypertension

Benign intracranial hypertension (pseudotumor cerebri) — headache, visual changes, papilledema

—

Slipped capital femoral epiphysis

SCFE risk in children — limp, hip/knee pain (requires surgery)

—

Scoliosis progression

Rapid growth may unmask/progress scoliosis (monitor spine in children)

—

Hypothyroidism

Central hypothyroidism unmasking or worsening (monitor TSH, free T4)

—

Cancer risk

Contraindicated in active malignancy. Theoretical risk in cancer survivors (controversial).

Theoretical via angiogenesis pathway

Antibody formation

Rare (<2%), typically non-neutralizing. Loss of efficacy if neutralizing antibodies develop.

No data (no long-term human trials)

Pancreatitis

Rare. Higher risk in children with certain syndromes (Prader-Willi).

—

Gynecomastia

Adolescent males (physiological during puberty, may be exacerbated)

—

GI symptoms

—

Rare nausea (anecdotal)

Lethargy / fatigue

—

Reported anecdotally during loading phase

Pregnancy / OB

—

Avoid

Long-term safety

—

Unknown beyond Phase 2

Absolute Contraindications

HGH 191AA

·Active malignancy or history of cancer (especially childhood cancer survivors with risk factors)
·Acute critical illness (post-cardiac surgery, trauma, acute respiratory failure)
·Diabetic retinopathy (active proliferative or severe non-proliferative)
·Prader-Willi syndrome with severe obesity, sleep apnea, or respiratory impairment
·Closed epiphyses (for growth indications)

TB-500

·Active malignancy (theoretical angiogenesis concern)
·Pregnancy / breastfeeding

Relative Contraindications

HGH 191AA

·Diabetes mellitus (monitor closely, may require insulin adjustment)
·Intracranial lesions or history of intracranial hypertension
·Scoliosis (monitor curve progression)
·Untreated hypothyroidism (treat before GH initiation)
·Severe obesity (assess OSA risk, cardiovascular status)

TB-500

·Cancer history
·Concurrent VEGF inhibitor therapy

05Administration Protocol

Parameter

HGH 191AA

TB-500

1. Reconstitution (if lyophilized)

Add diluent (sterile water or bacteriostatic water per manufacturer) to vial. Swirl gently — do not shake. Solution should be clear, colorless. Concentration varies by brand (e.g., 5 mg or 10 mg per vial).

Add 1–2 mL bacteriostatic water to 5 mg vial → 2.5–5 mg/mL. Roll gently.

2. Injection site

Subcutaneous — rotate sites: abdomen, thigh, buttocks, upper arm. Avoid same site within 1 cm for 2 weeks to prevent lipodystrophy.

SQ near injury site (preferred), or systemic SQ (abdomen). Rotate sites.

3. Timing

Once daily, evening preferred (6–8 PM or pre-sleep). Mimics physiological nocturnal GH secretion. Consistency is critical.

Evening or pre-sleep is most common anecdotal timing.

4. Storage

Unreconstituted: refrigerate 2–8 °C, protect from light. Reconstituted: refrigerate, use within 14–28 days (brand-specific). Do not freeze.

Lyophilised: room temp, light-protected. Reconstituted: refrigerate, ≤30 days.

5. Needle

27–31G, 4–8 mm insulin syringe or pen device. Pinch skin, 45–90° angle depending on subcutaneous thickness.

27–31G, 4–8 mm insulin syringe.

6. Monitoring

Baseline and periodic: IGF-1 (target age/sex-adjusted midrange), fasting glucose, HbA1c, thyroid function (TSH, free T4), bone age (children), lipid panel. Fundoscopy if headache/visual symptoms.

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06Stack Synergy

HGH 191AA

+ Ipamorelin

Moderate

View Ipamorelin →

Ipamorelin (GHRP) stimulates endogenous GH release, which is redundant when exogenous rhGH is administered. However, ipamorelin may still amplify pulsatility of remaining endogenous secretion in partial GHD or during GH dose titration. Not typically combined in standard clinical practice; more common in experimental or off-label protocols. Limited evidence for additive benefit.

HGH 191AA: Standard dose per indication
Ipamorelin: 100–200 mcg SQ · morning (if used)
Note: Monitor IGF-1 closely; avoid supraphysiological levels
Primary benefit: Theoretical enhancement of pulsatility; limited clinical rationale

+ Tesamorelin

Weak

View Tesamorelin →

Tesamorelin (GHRH analogue) stimulates endogenous GH secretion, which is unnecessary when exogenous rhGH is already provided. Combining both offers no mechanistic advantage and increases cost, side effects, and IGF-1 elevation risk. Not recommended in clinical practice.

Note: Combination not recommended — choose one GH modality
Primary benefit: None — redundant mechanisms

TB-500

+ BPC-157

Strong

View BPC-157 →

TB-500 and BPC-157 cover complementary halves of tissue repair: BPC-157 upregulates VEGFR2-driven angiogenesis and fibroblast outgrowth; TB-500 sequesters G-actin to enable endothelial / epithelial migration. The anecdotal canonical "healing stack" — pairs especially well for tendon and ligament injuries.

TB-500: 2 mg SQ · 2× per week
BPC-157: 250–500 mcg SQ · daily
Primary benefit: Combined angiogenesis + cell migration for tendon/ligament/muscle repair