Tesamorelin
The only growth-hormone-releasing hormone analog with FDA approval — studied for visceral fat reduction, cognition, and metabolic health.
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What Is Tesamorelin?
Tesamorelin is a synthetic 44-amino-acid analog of growth-hormone-releasing hormone (GHRH). Marketed as Egrifta, it is the only GHRH analog ever approved by the FDA — initially for HIV-associated lipodystrophy, the visceral fat accumulation seen in patients on long-term antiretroviral therapy.
Outside its labeled indication, tesamorelin has become one of the most-studied peptides in research settings investigating visceral adiposity, hepatic fat, cognitive function in older adults, and the broader physiology of pulsatile growth hormone release. Its FDA history gives it a deeper safety dataset than nearly any other research peptide on the market.
Tesamorelin is supplied as a lyophilized powder requiring reconstitution with bacteriostatic water. It is administered subcutaneously, typically once daily before bed to align with the body's natural overnight GH pulse.
History & Discovery
Tesamorelin was developed by Theratechnologies, a Quebec-based biotech, beginning in the late 1990s. The molecule was rationally designed by adding a trans-3-hexenoic acid group to the N-terminus of native human growth hormone-releasing hormone (hGHRH 1-44), conferring resistance to dipeptidyl peptidase-4 (DPP-4) — the enzyme that rapidly degrades native GHRH within minutes of release.
The pivotal phase 3 program targeted HIV-associated lipodystrophy (HALS) — the disfiguring abdominal fat accumulation that emerged as a chronic complication of the first generation of antiretroviral therapy. Two large multicenter trials (M-1010 and M-1011) demonstrated significant visceral adipose tissue reductions versus placebo, leading to FDA approval in November 2010 under the brand name Egrifta.
Egrifta remains the only GHRH analog with active FDA approval — a meaningful distinction in a class otherwise populated entirely by research-only compounds (CJC-1295, sermorelin, MOD-GRF). A reformulated version, Egrifta SV, replaced the original in 2019 with a longer reconstituted shelf life and simpler administration.
Off-label and investigational research has expanded steadily since approval, examining tesamorelin for non-alcoholic fatty liver disease (NAFLD/NASH), cognitive function in healthy older adults and those with mild cognitive impairment, and HIV-associated neurocognitive disorder.
Mechanism of Action
Tesamorelin binds to the GHRH receptor on somatotroph cells of the anterior pituitary, stimulating endogenous secretion of growth hormone in a pulsatile, physiological pattern. Unlike direct administration of recombinant human growth hormone (rhGH), tesamorelin preserves the negative-feedback loop — the body still down-regulates GH release when IGF-1 rises, which is thought to reduce side-effect risk.
Downstream, the released GH stimulates hepatic IGF-1 production. Elevated GH and IGF-1 drive lipolysis (preferentially in visceral adipose tissue), influence body composition, support tissue repair, and modulate sleep architecture and cognitive performance via central GH receptor activity.
The 44-amino-acid sequence of tesamorelin is stabilized by the addition of a trans-3-hexenoic acid group at the N-terminus, which dramatically extends its plasma half-life relative to native GHRH (1-44).
Pharmacokinetics
| Molecular weight | 5,196 Da (44 amino acids) |
| Bioavailability (subQ) | Approximately 4% (well within clinical efficacy range due to GHRH-receptor amplification) |
| Time to peak (Tmax) | ~15 minutes after subcutaneous injection |
| Half-life (T½) | ~26 minutes in healthy adults; ~38 minutes in HIV-LD patients |
| Metabolism | Enzymatic peptide cleavage; no CYP450 involvement |
| Elimination | Renal clearance of peptide fragments |
| Onset of GH pulse | GH peak ~15–30 minutes post-injection |
| Steady-state IGF-1 rise | Plateau by 2 weeks of daily dosing |
Research Use Cases
Visceral Adipose Tissue Reduction
The original FDA-approved use case. Multi-center trials documented average VAT reductions of 15–18% over 26 weeks, with preferential loss from the abdominal cavity rather than subcutaneous fat.
Non-Alcoholic Fatty Liver Disease (NAFLD)
Hepatic fat content has been studied as a secondary endpoint, with measurable reductions in liver fat fraction observed via MRI proton density fat fraction imaging.
Cognitive Function in Older Adults
Studies at Massachusetts General Hospital have evaluated tesamorelin in adults with mild cognitive impairment, examining executive function, memory, and verbal fluency endpoints.
Sleep Architecture
Restoration of slow-wave (deep) sleep is a recurring observation in research populations, consistent with the GH–sleep relationship documented since the 1960s.
IGF-1 Restoration in Adult-Onset GH Deficiency
Used in research contexts to evaluate physiological GH-axis restoration without supraphysiologic spikes typical of exogenous rhGH.
Body Composition in Aging
Studied for its effect on lean mass preservation and adipose redistribution in aging populations where natural GH secretion declines.
Research Dosing Reference
FDA-approved (Egrifta SV) clinical dosing
Indicated for HIV-associated lipodystrophy. Given pre-bed to align with endogenous GH pulse.
Research dose — visceral fat reduction (non-HIV)
Most-replicated research dose for non-HIV VAT studies; matches the original phase 2 dose-finding work.
Research dose — cognitive endpoints
Schedule used in MGH cognitive function studies in adults with mild cognitive impairment.
Conservative starter (research)
Used in research contexts to assess tolerability of the IGF-1 rise before escalating.
Stacking & Combinations
Tesamorelin + Ipamorelin
Pairs a GHRH analog with a ghrelin-mimetic GHRP. The two mechanisms act on different pituitary receptors — the GHRH arm sets pulse amplitude, the GHRP arm increases the number of releasing somatotrophs — producing a GH pulse 2–4× larger than either compound alone, with negligible additional side effect burden.
Tesamorelin + BPC-157 (recovery research)
Investigated in some recovery research contexts where elevated GH/IGF-1 from tesamorelin is hypothesized to support the systemic healing modulation BPC-157 provides locally — though the combination has no clinical trial evidence.
Tesamorelin + Tirzepatide (preliminary VAT research)
An emerging research direction — tirzepatide drives broad weight loss, tesamorelin specifically targets visceral fat. Preliminary investigation only; no published trial data.
Side Effect Profile
Common / Mild-to-Moderate
- •Injection-site reactions (redness, itching, swelling) — most-reported AE in trials
- •Arthralgia (joint discomfort), often resolving over weeks
- •Mild peripheral edema and water retention
- •Myalgia (muscle aches) early in therapy
- •Mild nausea, especially in first 1–2 weeks
- •Glycemic dysregulation — modest fasting glucose rise in some subjects
Serious / Less Common
- •Hyperglycemia / new-onset glucose intolerance in predisposed subjects
- •Hypersensitivity reactions including, rarely, anaphylaxis
- •Worsening of pre-existing diabetic retinopathy
- •Theoretical concern: contraindicated in active malignancy (GH/IGF-1 elevation)
Tesamorelin's negative-feedback-preserving mechanism gives it a more favorable side-effect profile than exogenous rhGH, but it is not free of metabolic risk. Glucose monitoring (fasting glucose, HbA1c) is the standard parameter tracked in research and clinical use. Ophthalmologic screening is recommended for subjects with diabetes.
Storage & Reconstitution
- Lyophilized vials are stored refrigerated at 2–8°C (36–46°F). Do not freeze.
- Reconstitute with bacteriostatic water for injection (BAC water). For a 5 mg vial, 1–2 mL is the standard volume — yielding 5 mg/mL or 2.5 mg/mL respectively.
- Inject the BAC water against the side of the vial slowly. Swirl gently — do not shake — until the powder is fully dissolved (typically under 30 seconds).
- Once reconstituted, the solution is stable refrigerated for approximately 14 days per the Egrifta SV label. Many research protocols use the reconstituted vial within 14–21 days.
- Draw the dose with an insulin syringe (typically 31G, 5/16-inch). For a 5 mg/mL concentration, 1 mg = 0.2 mL = 20 units on a 100-unit insulin syringe.
- Inject subcutaneously into clean abdominal skin, rotating sites to avoid lipohypertrophy.
- Allow refrigerated solution to reach room temperature before injection to reduce sting.
Key Studies & Trial Data
Effects of tesamorelin on visceral fat in HIV lipodystrophy (M-1010)
Pivotal phase 3 trial. 412 HIV-infected adults with abdominal lipohypertrophy randomized to 2 mg tesamorelin daily or placebo for 26 weeks. Tesamorelin produced a 15.2% reduction in visceral adipose tissue (VAT) versus a 5% increase in the placebo arm — a ~20-percentage-point absolute difference.
Falutz J, et al. NEJM. 2007;357(23):2359–2370.
Long-term safety and efficacy in HIV-associated lipodystrophy (M-1011)
52-week extension/replication trial. Continued tesamorelin maintained VAT reduction; subjects switched from placebo to active drug at week 26 showed catch-up VAT loss. Glycemic parameters were monitored throughout with no clinically significant deterioration in the overall cohort.
Falutz J, et al. JAIDS. 2010;53(3):311–322.
Tesamorelin reduces hepatic fat in HIV-infected adults
Randomized trial showing significant reductions in liver fat fraction by MR spectroscopy in HIV-infected adults treated with tesamorelin — extending the visceral-fat finding into the hepatic compartment.
Stanley TL, et al. Lancet HIV. 2014;1(1):e25–e34.
Tesamorelin and cognitive function in MCI
20-week pilot investigating tesamorelin in adults with mild cognitive impairment (MCI). Treated subjects showed improvements in executive function and verbal memory versus placebo, with associated changes in cerebrospinal fluid biomarkers.
Baker LD, et al. Arch Neurol. 2012;69(11):1420–1429.
Comparisons & Deep Dives
In-depth articles on Peptide Basics that compare Tesamorelin to related compounds and expand on its mechanism and use.
Tesamorelin vs Ipamorelin
Two GH-pathway peptides with very different mechanisms. Tesamorelin is a GHRH analog. Ipamorelin is a GHRP. Comparison of cost, half-life, and visceral fat data.
How Tesamorelin Works
Deep dive into the GHRH-receptor mechanism, the pulsatile-vs-continuous GH debate, and why preserved feedback matters.
How Growth Hormone Peptides Work
The full landscape — GHRH analogs (tesamorelin, sermorelin, CJC-1295) versus ghrelin mimetics (ipamorelin, GHRP-2/6, hexarelin).
Frequently Asked Questions
Where to Source Research-Grade Tesamorelin
Base Peptide
Research-grade tesamorelin (5 mg vial) with batch-specific Certificate of Analysis confirming purity by HPLC and identity by mass spectrometry. Lyophilized powder, requires reconstitution with bacteriostatic water.
Other reputable suppliers known for batch-specific Certificates of Analysis:
Want a deeper, ongoing reference? Peptide Basics maintains a comprehensive resource on tesamorelin alongside calculators, reconstitution guides, and a database of 60+ research peptides.
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