PwPepwise

Tesamorelin

Growth Hormone

a.k.a. Egrifta

GHRH analog

Tesamorelin is a synthetic analog of growth hormone-releasing hormone (GHRH), the body's natural signal for stimulating growth hormone production.

§Dosing at a glance

4 protocols · from the research
What it's forDoseHow oftenHowFor how long
HIV-Associated Lipodystrophy (FDA-Approved Indication)2 mgOnce dailySubcutaneousInjected just under the skin, into the fat layer.26–52 wks
HIV-Associated Non-Alcoholic Fatty Liver Disease (NAFLD)2 mgOnce dailySubcutaneousInjected just under the skin, into the fat layer.12 mos
Cognitive Function in Older Adults / Mild Cognitive Impairment1 mgOnce dailySubcutaneousInjected just under the skin, into the fat layer.—
Obese Adults with Reduced Growth Hormone Secretion2 mgOnce dailySubcutaneousInjected just under the skin, into the fat layer.12 mos

Approximate values pulled from the research — double-check before dosing.

§01Summary

Tesamorelin is a synthetic analog of growth hormone-releasing hormone (GHRH), the body's natural signal for stimulating growth hormone production. Rather than directly introducing growth hormone, it works by activating the pituitary gland to release growth hormone in a more physiologically normal, pulsatile pattern, which in turn raises levels of insulin-like growth factor 1 (IGF-1).

The most well-established benefit of tesamorelin is a meaningful reduction in visceral adipose tissue — the metabolically harmful fat that accumulates deep in the abdomen. In people living with HIV who develop excess abdominal fat as a side effect of antiretroviral therapy, tesamorelin reduces visceral fat by approximately 15% compared to placebo1,5, while also improving triglyceride levels1,4 and the cholesterol-to-HDL ratio1,5. These benefits require ongoing treatment to be maintained2,4. Beyond body composition, tesamorelin reduces liver fat in HIV-associated fatty liver disease7, and early research suggests it may support cognitive function in older adults and those with mild cognitive impairment3. It is FDA-approved for HIV-associated lipodystrophy and has a well-characterized safety profile, with multiple clinical trials finding no meaningful worsening of blood sugar control despite its stimulation of the growth hormone axis1,2,5,8,16.

This is the layperson summary. Mechanism, dosing, the evidence base, and the published literature are in the sections below — every claim links to its source.

§02In depth

Tesamorelin (TH9507) is a synthetic analog of endogenous human growth hormone-releasing hormone (GHRH), consisting of the full 44-amino acid sequence of GHRH(1-44) conjugated to a trans-3-hexenoic acid moiety at the N-terminus to confer enhanced plasma stability and resistance to enzymatic degradation compared to native GHRH.

Tesamorelin binds to and activates the GHRH receptor (GHRHR), a Gs protein-coupled receptor expressed predominantly on somatotroph cells of the anterior pituitary. Receptor activation stimulates adenylyl cyclase, increases intracellular cAMP, and triggers both the synthesis and pulsatile secretion of growth hormone (GH). Unlike continuous exogenous GH administration, tesamorelin preserves the physiological pulsatile pattern of GH release, which is thought to underlie its favorable metabolic safety profile — particularly the absence of clinically meaningful glucose dysregulation observed across multiple trials despite substantial IGF-1 elevation1,2,5. GH secreted in response to tesamorelin acts on peripheral tissues, primarily the liver, to stimulate IGF-1 synthesis, with IGF-1 increasing by 81–117% above placebo-adjusted baseline levels in clinical studies1,3.

At the tissue level, GH/IGF-1 axis activation promotes lipolysis preferentially in visceral adipose tissue (VAT), which is characterized by higher GH receptor density and greater lipolytic sensitivity than subcutaneous adipose tissue. This depot-specific sensitivity explains the selective visceral fat reduction — without significant subcutaneous fat loss — observed consistently across trials5,8,11. VAT reduction in turn drives downstream improvements in circulating triglycerides, cholesterol-to-HDL ratio, and adiponectin levels, as well as reductions in fibrinolytic and inflammatory biomarkers including tPA antigen; these associations remain significant after controlling for IGF-1 changes, indicating they are mediated through adipose tissue remodeling rather than direct GH/IGF-1 signaling6,9.

In the liver, tesamorelin's effects extend beyond indirect lipid regulation. Hepatic transcriptomic analysis of biopsy specimens from HIV-infected individuals with NAFLD reveals upregulation of gene sets involved in oxidative phosphorylation and downregulation of inflammatory, tissue repair, and cell proliferation pathways15. FGF21 — a hepatokine elevated as a compensatory response to hepatic steatosis — decreases in association with liver fat reduction under tesamorelin treatment, with this reduction correlating with improvements in GGT and FIB4 fibrosis index18. In mitochondrial function studies, IGF-1 increases induced by tesamorelin correlate significantly with improvements in phosphocreatine recovery kinetics measured by ³¹P magnetic resonance spectroscopy, suggesting an IGF-1-mediated enhancement of skeletal muscle mitochondrial oxidative capacity19. In the central nervous system, 20 weeks of tesamorelin treatment increases GABA levels across multiple brain regions, increases N-acetylaspartylglutamate (NAAG) in the dorsolateral frontal cortex, and decreases myo-inositol in the posterior cingulate cortex, with IGF-1 changes correlating with GABA changes (r=0.47), consistent with an IGF-1-mediated pathway for central neurochemical modulation13.

§04Evidence & efficacy

Evidence base
146Studies
89Human
1Animal

HIV-Associated Visceral Lipodystrophy: Tesamorelin 2 mg/day reduces visceral adipose tissue by approximately 15% compared to placebo over 26 weeks in HIV-infected individuals with abdominal fat accumulation, as demonstrated across multiple independent RCTs and a pooled Phase 3 analysis1,2,5. With continuous therapy, reductions approach 18% at 52 weeks4,5. Triglycerides are reduced by approximately 37–50 mg/dL versus placebo1,5,8, and the total cholesterol-to-HDL ratio improves significantly1,5. Patient- and physician-rated body image outcomes also improve2,5. Effects are selective for visceral fat, with subcutaneous adipose tissue and BMI not significantly affected5,11. Lean body mass increases modestly with treatment11. Metabolic benefits — including lipid improvements — are directly proportional to the degree of VAT reduction achieved, and patients who do not achieve meaningful VAT reduction show attenuated metabolic benefit9.

HIV-Associated Non-Alcoholic Fatty Liver Disease: Tesamorelin reduces hepatic fat fraction by an absolute 4.1 percentage points (relative −37%) compared to placebo over 12 months, with 35% of treated patients achieving liver fat normalization versus 4% on placebo7. Liver fat reduction was also observed in a smaller 6-month study12. Favorable modulation of hepatic transcriptomic signatures — including upregulation of oxidative phosphorylation pathways and downregulation of inflammatory and fibrotic gene sets — has been reported in liver biopsy specimens15.

Non-HIV Metabolic Populations: In obese adults with reduced GH secretion, tesamorelin reduces visceral adipose tissue, triglycerides, C-reactive protein, and carotid intima-media thickness compared to placebo over 12 months8. Lipid benefits were also observed in type 2 diabetic patients at the 2 mg dose16.

Cognitive Function: Tesamorelin may improve overall cognitive composite scores and executive function in healthy older adults and adults with mild cognitive impairment after 20 weeks of treatment3. Associated increases in brain GABA levels and decreases in myo-inositol — a biomarker elevated in Alzheimer pathology — have been reported13.

Immunomodulation and Inflammation: Tesamorelin may reduce circulating markers of immune activation and inflammatory fibrinolytic markers in HIV-infected individuals, with effects correlating with the degree of visceral fat reduction6,17.

Evidence Rating: Strong for HIV-associated lipodystrophy; Moderate for HIV-associated NAFLD; Preliminary for cognitive function and non-HIV metabolic indications.

Rating Rationale: The Strong rating for HIV-associated lipodystrophy is supported by multiple independent large RCTs meeting their prespecified primary endpoints1,2,4,5, a pooled Phase 3 analysis5, and a meta-analysis11, with consistent effect sizes across trials — the basis for FDA approval. The Moderate rating for HIV-associated NAFLD reflects a single adequately-powered RCT meeting its primary endpoint7 supported by mechanistic biopsy and transcriptomic data15, but requiring independent replication and histological confirmation of fibrosis outcomes. The Preliminary rating for cognitive function reflects a single adequately-powered RCT3 with supportive neurochemical data13 but no independent replication. Non-HIV metabolic and immunomodulatory findings6,8,16,17 are similarly rated Preliminary, each supported by single trials without replication in independent cohorts.

§05Safety

Tesamorelin has been evaluated across multiple large randomized controlled trials and a meta-analysis, collectively establishing a well-characterized safety profile.

Glycemic Safety: Across HIV-lipodystrophy trials, no clinically meaningful changes in fasting glucose or HbA1c were observed despite substantial increases in IGF-1 (up to 108 ng/mL above placebo)1,2,5. A transient early increase in fasting glucose was noted at 2 weeks in one study but resolved by 6 months12. In a dedicated trial in patients with type 2 diabetes, tesamorelin did not significantly alter insulin response, fasting glucose, or HbA1c over 12 weeks, and no patients discontinued due to loss of diabetes control16. In the cognitive function trial, a 35% increase in fasting insulin was observed specifically in adults with mild cognitive impairment, though levels remained within the normal range3.

Common Adverse Events: The meta-analysis identified arthralgia, myalgia, paresthesia, and injection-site reactions (including erythema) as the most consistently reported adverse events11. Injection site complaints were more frequent in the tesamorelin arm of the NAFLD trial7. In cognitive studies, 68% of GHRH-treated participants reported adverse events compared to 36% in the placebo group, though events were generally mild3.

Immunological Safety: CD4+ T-cell counts were unaffected by tesamorelin treatment in HIV-infected populations11, and tesamorelin was associated with reductions rather than increases in circulating inflammatory and immune activation markers17.

IGF-1 Elevation: IGF-1 levels rise substantially with tesamorelin treatment — by 81–117% depending on the study population1,3 — and monitoring of IGF-1 levels is warranted during treatment.

Diabetic Retinopathy: A dedicated randomized trial was registered to evaluate whether tesamorelin increases the risk of diabetic retinopathy development or progression in HIV-infected patients with concomitant type 2 diabetes, reflecting appropriate regulatory scrutiny of this theoretical risk20.

Durability of Effects: Benefits are treatment-dependent; visceral fat rapidly reaccumulates upon discontinuation2,4, which is a clinically important consideration for long-term treatment planning rather than a safety concern per se.

§06History

Tesamorelin emerged from research into the therapeutic potential of synthetic GHRH analogs as an alternative to direct GH replacement therapy. The compound was developed by Theratechnologies, a Canadian biopharmaceutical company, with the key innovation being the conjugation of the full 44-amino acid GHRH sequence to a trans-3-hexenoic acid moiety, substantially improving the peptide's stability relative to native GHRH.

Clinical development was driven by the significant unmet need in HIV-infected patients receiving combination antiretroviral therapy, who frequently develop HIV-associated lipodystrophy — a disfiguring and metabolically harmful syndrome characterized by excess visceral fat accumulation, hyperlipidemia, and insulin resistance. The first pivotal Phase 3 randomized controlled trial, published in the New England Journal of Medicine in 2007, demonstrated robust visceral fat reduction and lipid improvements with an acceptable safety profile1. A second large RCT and long-term extension data followed2,4, and pooled analysis of both Phase 3 trials further solidified the efficacy and safety evidence base5.

In November 2010, the U.S. Food and Drug Administration approved tesamorelin (brand name EGRIFTA) for the reduction of excess abdominal fat in HIV-infected adults with lipodystrophy — the first and, at the time of approval, only pharmacological treatment approved for this indication1. Subsequent research expanded the evidence base into HIV-associated NAFLD7,12,15, cognitive aging3,13, non-HIV metabolic populations8,16, and immunomodulation17, reflecting a growing appreciation for the broad metabolic consequences of GH-axis dysregulation. The compound remains an active area of clinical and translational investigation.

§07References