Tesamorelin
Tesamorelin (Stabilized GHRH Analog)
Also known as: Egrifta, Egrifta SV, TH9507
Prompted by Jack Butcher (Visualize Value) · AI-authored by Claude · Research-sourced
FDA-approved GHRH analog (Egrifta) for HIV-associated lipodystrophy. The only GH secretagogue with FDA approval, producing pulsatile GH release that mimics natural physiology.
Quick Facts
FDA-approved as Egrifta/Egrifta SV for the reduction of excess abdominal fat in HIV-infected patients with lipodystrophy. Not approved for general weight management or anti-aging.
Overview
Tesamorelin is a synthetic analog of human growth hormone-releasing hormone (GHRH) consisting of the full 44-amino acid sequence of endogenous GHRH with a trans-3-hexenoic acid modification at the N-terminus. This modification provides enhanced stability and resistance to enzymatic degradation compared to native GHRH.
Tesamorelin was FDA-approved in 2010 (Egrifta) and reformulated in 2019 (Egrifta SV) specifically for the reduction of excess visceral adipose tissue (VAT) in HIV-infected patients with lipodystrophy — a condition characterized by abnormal fat accumulation in the trunk and abdomen as a side effect of antiretroviral therapy.
Unlike direct growth hormone administration, tesamorelin stimulates the pituitary gland to produce and release GH in a more physiological pulsatile pattern, which may reduce certain risks associated with exogenous GH therapy. It has attracted significant interest in the anti-aging and body composition optimization communities due to its potent visceral fat-reducing effects.
Mechanism of Action
Tesamorelin binds to and activates GHRH receptors on somatotroph cells in the anterior pituitary gland. This triggers the synthesis and pulsatile release of endogenous growth hormone through the cAMP/PKA signaling pathway.
The released GH acts on the liver to stimulate production of insulin-like growth factor-1 (IGF-1), which mediates many of GH's downstream metabolic effects. In adipose tissue, GH stimulates lipolysis through activation of hormone-sensitive lipase and suppresses lipogenesis by downregulating lipoprotein lipase activity.
Tesamorelin demonstrates preferential reduction of visceral adipose tissue (VAT) over subcutaneous fat. The mechanism for this selectivity is believed to relate to the higher density of GH receptors and greater lipolytic sensitivity of visceral adipocytes compared to subcutaneous fat depots.
The pituitary-mediated release pattern preserves negative feedback mechanisms — as GH and IGF-1 levels rise, somatostatin release increases to modulate further GH secretion. This feedback loop theoretically provides a safety advantage over exogenous GH administration, which bypasses pituitary regulation entirely.
Research Summary
Clinical trials supporting FDA approval demonstrated significant reductions in visceral adipose tissue. The Phase III program included two pivotal randomized, double-blind, placebo-controlled trials in HIV-infected patients with lipodystrophy.
In the combined analysis, tesamorelin 2 mg daily reduced trunk fat by approximately 15–18% over 26 weeks compared to a 5% increase with placebo, as measured by CT scan. Visceral adipose tissue area decreased by an average of 28 cm² versus an increase with placebo.
Beyond fat reduction, tesamorelin has shown favorable effects on lipid profiles, with reductions in triglycerides and improvements in total cholesterol-to-HDL ratios. Research also demonstrates potential benefits for hepatic steatosis (fatty liver) — a study by Stanley et al. showed significant reductions in liver fat fraction.
Emerging research has explored cognitive effects. A 20-week randomized controlled trial by Baker et al. demonstrated improvements in executive function and verbal memory in HIV-infected adults, potentially mediated through IGF-1-dependent neuroprotective mechanisms.
Key limitation: most clinical data comes from the HIV lipodystrophy population. Extrapolation to non-HIV populations for anti-aging or general body composition purposes is based on mechanistic reasoning rather than direct large-scale trials.
Key References
Effects of tesamorelin on body composition and metabolic parameters in HIV-infected patients
Falutz J, et al. · Journal of Clinical Endocrinology & Metabolism (2007) · 10.1210/jc.2007-0429
Phase II trial demonstrating dose-dependent reductions in visceral adipose tissue with tesamorelin in HIV-infected patients with lipodystrophy.
Effect of tesamorelin on visceral fat and liver fat in HIV-infected patients with abdominal fat accumulation
Falutz J, et al. · Journal of Acquired Immune Deficiency Syndromes (2010) · 10.1097/QAI.0b013e3181cbf951
Pivotal Phase III trial showing 15.2% reduction in trunk fat with tesamorelin 2 mg vs. 5% increase with placebo over 26 weeks.
Tesamorelin reduces liver fat and liver fat-related inflammation in HIV-associated NAFLD
Stanley TL, et al. · Journal of Clinical Investigation (2019) · 10.1172/JCI120985
Demonstrated that tesamorelin significantly reduced hepatic fat fraction and markers of liver inflammation, suggesting potential therapeutic role in NAFLD.
Effects of tesamorelin on cognition in HIV-infected patients with reduced growth hormone
Baker LD, et al. · Neurology (2023) · 10.1212/WNL.0000000000207180
Randomized controlled trial showing improvements in executive function and verbal memory with 20 weeks of tesamorelin treatment in HIV-infected adults.
Protocols
HIV lipodystrophy (FDA-approved)
Inject into the abdomen. Rotate injection sites. Administer at the same time each day. Egrifta SV is the current formulation (single vial reconstitution).
Body composition optimization (off-label)
Off-label use. Some practitioners use lower doses (1 mg) or alternate-day dosing to manage IGF-1 elevation. Administer on an empty stomach for optimal GH release. Often combined with ipamorelin.
Side Effects & Safety
| Frequency | Effect |
|---|---|
| common | Injection site reactions Erythema, pruritus, pain, or irritation at the injection site. Reported in approximately 8–13% of patients. |
| common | Arthralgia (joint pain) Consistent with GH-mediated effects. Affects approximately 10–13% of users. |
| uncommon | Peripheral edema Fluid retention and swelling, particularly in extremities. Related to GH-induced sodium and water retention. |
| uncommon | Paresthesia (tingling/numbness) Carpal tunnel-like symptoms due to fluid retention. Usually resolves with continued use or dose reduction. |
| uncommon | Hyperglycemia GH antagonizes insulin action. Monitor fasting glucose and HbA1c, particularly in patients with diabetes risk. |
| rare | Hypersensitivity reactions Rash, urticaria, and in rare cases anaphylaxis. Discontinue if significant hypersensitivity occurs. |
Contraindications
- —Active malignancy (GH and IGF-1 may promote tumor growth)
- —Disruption of the hypothalamic-pituitary axis due to hypophysectomy, hypopituitarism, or pituitary tumor/surgery
- —Known hypersensitivity to tesamorelin or mannitol
- —Pregnancy (Category X — may cause fetal harm)
Interactions
- —May reduce efficacy of insulin and oral hypoglycemics due to GH-mediated insulin resistance
- —Glucocorticoids may attenuate the GH-releasing effect of tesamorelin
- —May alter metabolism of drugs processed by CYP450 enzymes through GH/IGF-1 mediated changes in hepatic enzyme activity
- —Concurrent use with exogenous GH is not recommended (additive IGF-1 elevation)
Reconstitution & Storage
Related Peptides
Tesamorelin is sometimes compared to the CJC-1295/Ipamorelin combination, as both approaches stimulate endogenous GH release. Tesamorelin has the advantage of FDA approval and clinical data, while CJC-1295/Ipamorelin is preferred in some protocols for its flexibility in dosing and combination potential.