Tesamorelin (HIV lipodystrophy)

Tesamorelin is human GHRH(1-44) with a trans-3-hexenoyl group attached to the N-terminal tyrosine, which blocks cleavage by dipeptidyl peptidase-4 and extends the peptide's usable life without changing what it does at the receptor. It acts on somatotroph GHRH receptors to increase endogenous, still-pulsatile GH release, so IGF-1 rises but the physiological feedback loop stays intact, unlike exogenous somatropin. Visceral adipose tissue is unusually sensitive to GH-driven lipolysis, and in the pivotal trials tesamorelin reduced visceral adipose tissue by roughly 15 to 18 percent over 26 weeks while leaving subcutaneous fat largely alone. Later work showed reductions in liver fat as well, which is where most of the current research interest sits. Benefits reverse within weeks of stopping, so it is a maintenance drug, not a course.

Targets: GHRH receptor, Pituitary somatotrophs, IGF-1, Visceral adipose tissue lipolysis

• · 1.28 mg daily, drawn as 0.16 mL from a vial reconstituted once a week rather than daily. This is the formulation now supplied in the US.
• · 1.4 mg daily from a single 2 mg vial reconstituted daily. Superseded by Egrifta WR.
• · 2 mg daily reconstituted from two 1 mg vials. Historical, no longer the marketed presentation.

Work out your exact syringe units →

• very commonInjection-site erythema, pruritus and pain— The most common complaint; rotate sites.
• commonArthralgia and peripheral oedema— Classic GH-mediated fluid retention.
• commonCarpal tunnel symptoms and paraesthesia— Same mechanism as with GH therapy.
• commonImpaired glucose tolerance and new diabetes— GH is counter-regulatory. HbA1c must be tracked, especially in patients already at risk.
• commonRise in IGF-1 above the age-adjusted range— The theoretical malignancy concern rests on this; there is no confirmed cancer signal in trials.
• uncommonHypersensitivity reactions including rash and urticaria

• Active malignancy, given the IGF-1 elevation
• Disruption of the hypothalamic-pituitary axis from hypophysectomy, pituitary tumour or surgery, head irradiation or head trauma
• Pregnancy
• Known hypersensitivity to tesamorelin or mannitol

• synergyipamorelin — GHRH analogues and ghrelin-receptor agonists amplify each other's GH pulse; commonly stacked off-label, though not studied for this indication.
• redundantsomatropin — Both raise GH activity; combining them defeats the point of preserving pulsatility.
• cautioninsulin-icodec — GH elevation raises insulin requirements.

• · IGF-1 at baseline and periodically
• · Fasting glucose and HbA1c
• · Waist circumference or CT-measured visceral adipose tissue at 6 months to judge response
• · Standard age-appropriate cancer screening

Prescription drug in the US for HIV-associated lipodystrophy only. Widely used off-label and sold on the research-chemical market for general visceral fat reduction, which is not an approved indication.

• Egrifta WR FDA prescribing information (label)
• Falutz et al. 2007 NEJM, randomised trial of tesamorelin in HIV patients with abdominal fat accumulation (trial)
• Stanley et al. 2014 JAMA, tesamorelin effects on liver fat in HIV-associated lipodystrophy (trial)

Tesamorelin is a secretagogue, not a hormone, and that distinction drives everything. It binds the GHRH receptor on pituitary somatotrophs, a class B GPCR, raising cyclic AMP and calcium influx and triggering release of stored growth hormone. Because the release is from the pituitary and remains under hypothalamic somatostatin control, the resulting GH profile stays pulsatile and the IGF-1 negative feedback loop stays intact. That is the substantive difference from exogenous somatropin, which floods the system with a flat, feedback-independent GH signal, and it is why tesamorelin cannot easily produce the extreme IGF-1 elevations that recombinant GH can. The reason visceral fat responds preferentially is a tissue-level property rather than a targeting property: visceral adipocytes express more GH receptor and are markedly more sensitive to GH-driven lipolysis than subcutaneous adipocytes, which is exactly the reverse of what happens in growth hormone deficiency where visceral fat accumulates first. GH activates hormone-sensitive lipase and inhibits lipoprotein lipase in adipose tissue, and in visceral depots that shifts the balance sharply toward net lipolysis. Roughly 15 to 18 percent reduction in visceral adipose tissue over 26 weeks, with subcutaneous fat essentially untouched, is the pivotal trial result. The liver fat effect, demonstrated separately in the JAMA and Lancet HIV studies, follows from reduced visceral lipolytic flux to the portal circulation plus direct hepatic GH signalling, and it is where most current research interest sits. The counter-regulatory cost is unavoidable: GH antagonises insulin action in muscle and liver, so glucose tolerance worsens, and that is not a side effect that can be engineered away without losing the benefit.

The response is not universal and the drug is not titratable, so the 6-month assessment is the whole decision. About a third of patients do not achieve a meaningful visceral fat reduction and continuing them is money spent for nothing. Second, the benefit reverses: visceral fat returns within roughly 6 months of stopping, so this is maintenance therapy indefinitely, not a course, and framing it as a cycle is simply wrong. Third, glucose: GH is counter-regulatory and impaired glucose tolerance is common, which in a population already carrying antiretroviral-associated metabolic burden is not trivial. Fourth, fluid retention, arthralgia and carpal tunnel symptoms are classic GH effects and are the second commonest reason for discontinuation. Fifth, the reconstitution routines differ between formulations and people get them wrong when switching: Egrifta WR uses 1 mL of sterile water for a vial that lasts a week at room temperature, whereas the older F4 formulation was reconstituted with 0.5 mL daily and used immediately. Sixth, and this matters for this site's readership: tesamorelin is widely sold on the research-chemical market for general visceral fat reduction in people without HIV. The mechanism would be expected to work, the NAFLD data are genuinely interesting, but there is no approved indication, no dosing guidance outside the HIV population, no supply-chain assurance on grey-market material, and the glucose consequences apply just as much to someone using it cosmetically as to someone using it on label.

1. 1.28 mgOngoing, Egrifta WR (F8 formulation) — 1.28 mg subcutaneously once daily, drawn as 0.16 mL from a vial reconstituted once a week with 1 mL of the supplied sterile water. Inject into the abdomen, rotating sites, usually at bedtime to align with natural GH pulsatility. Fixed dose, no titration.
2. 1.4 mgEgrifta SV (F4 formulation), superseded — 1.4 mg daily from a single 2 mg vial reconstituted daily with 0.5 mL. Historical in the US.
3. 2 mgOriginal Egrifta, historical — 2 mg daily reconstituted from two 1 mg vials. No longer the marketed presentation.
4. —Month 6 decision point — Reassess response at 6 months. Non-responders are discontinued rather than escalated, because there is no higher approved dose.

• GHRH receptor on pituitary somatotrophs — Comparable to native GHRH; the hexenoyl modification does not change receptor interaction. Numeric affinity not resolved this session.

  Gs-cyclic AMP and calcium-dependent release of stored growth hormone, preserving pulsatility and intact IGF-1 feedback, unlike exogenous somatropin.

• Growth hormone receptor on visceral adipocytes (indirect, via released GH)

  Activation of hormone-sensitive lipase and inhibition of lipoprotein lipase, producing preferential visceral fat lipolysis with little effect on subcutaneous fat.

• Hepatic GH receptor and IGF-1 production (indirect)

  IGF-1 rises within days. This mediates most systemic GH effects and is also the basis of the theoretical malignancy concern and the fluid retention, arthralgia and carpal tunnel symptoms.

• Insulin signalling in muscle and liver (indirect)

  GH is counter-regulatory: insulin resistance increases, glucose tolerance worsens and new diabetes occurs in a minority. Unavoidable given the mechanism.

• Falutz 2007 phase 3 trial of tesamorelin in HIV with central adiposity Phase 3, randomised, double-blind, placebo-controlled · n=412 · 2007

  Change in visceral adipose tissue in HIV-infected patients with central adiposity, 86 percent male. Tesamorelin produced a substantial reduction in visceral fat versus placebo with subcutaneous fat largely preserved.

• Stanley 2014 visceral and liver fat trial Randomised clinical trial · 2014

  Effect of tesamorelin on visceral fat and liver fat in HIV-infected patients with abdominal fat accumulation. Confirmed preferential visceral fat targeting and demonstrated a reduction in hepatic fat.

• Stanley 2019 NAFLD trial Randomised, double-blind, multicentre · 2019

  Effects of tesamorelin on liver fat and histology in people with HIV and non-alcoholic fatty liver disease. This is the study that turned liver fat from a secondary observation into a research programme.

IGF-1 rises within days of starting, which is the fastest confirmation that the drug is being absorbed and is working at the pituitary. Measurable visceral fat reduction takes about 3 months and peaks around 6 months, which is why the pivotal trials ran to 26 weeks and why the response assessment sits at 6 months. Liver fat reduction follows a similar timescale. Fluid retention, arthralgia and carpal tunnel symptoms appear in the first weeks and often settle. Benefits reverse within about 6 months of stopping.

The combination that the grey market has settled on, tesamorelin plus a ghrelin receptor agonist such as ipamorelin, is mechanistically coherent: GHRH receptor activation and ghrelin receptor activation amplify each other's GH pulse because they act through different pathways on the same somatotroph, and ghrelin agonism additionally suppresses hypothalamic somatostatin tone. It has never been studied for this indication and it compounds the glucose and fluid-retention effects, so treat the amplification as real and the safety data as absent. Do not combine with somatropin, which floods the system and defeats the entire point of preserving pulsatility. In diabetic patients, insulin and oral agent doses usually need increasing, which is the opposite direction from most of the peptides in this class. In the HIV setting, tesamorelin does not interact meaningfully with antiretrovirals and does not affect viral load or CD4 count, which was an important early finding. Metformin is a rational co-prescription in anyone with borderline glucose tolerance.

Against somatropin: recombinant GH produces larger visceral fat reductions but at the cost of a flat, feedback-independent GH signal, far more fluid retention, arthralgia, carpal tunnel and glucose disturbance, and it suppresses endogenous GH secretion. Tesamorelin's preservation of pulsatility and IGF-1 feedback is its main safety argument, and it is a real one. Against the ghrelin-receptor secretagogues, ipamorelin, CJC-1295 and the rest of the grey-market GH-secretagogue world: tesamorelin is the only compound in that entire space with FDA approval for a body-composition indication and two positive phase 3 trials behind it, and that distinction should not be blurred. A forum post about ipamorelin and a NEJM trial of tesamorelin are not the same kind of evidence. Against GLP-1 receptor agonists for visceral fat: incretins produce far larger total weight loss but are not visceral-selective and cause substantial lean mass loss, whereas tesamorelin targets visceral fat specifically while sparing subcutaneous fat and lean tissue. In HIV lipodystrophy, where the problem is precisely visceral accumulation with peripheral wasting, that selectivity is the entire point and a GLP-1 would make the peripheral wasting worse.

$60–$6000/month. Unverified estimate spanning two entirely different markets. Branded Egrifta WR in the US runs to thousands of dollars a month; grey-market research-chemical tesamorelin sold for off-label visceral fat use is orders of magnitude cheaper, with correspondingly no assurance of identity, purity or sterility. Neither figure was sourced in this session.

• ?Volume of distribution is quoted by the label as 4.8 plus or minus 1.9 L/kg rather than in litres, so the litre field is null.
• ?Numeric clearance and plasma protein binding are not stated in the label, and no formal human metabolism studies exist.
• ?The half-life of 11 minutes is from healthy subjects; the Core record's 26 to 40 minutes reflects HIV-infected patients, and the difference is real rather than a discrepancy.
• ?Trial durations were not confirmed against the papers, so all are null. The pivotal trials ran to 26 weeks.
• ?The Stanley 2014 and 2019 enrolments were not confirmed.
• ?Efficacy and safety outside HIV-associated lipodystrophy, including for NAFLD in the general population, are not established, and no dosing guidance exists for that use.
• ?Cost figures are unverified estimates spanning legitimate and grey markets.

• Metabolic effects of a growth hormone-releasing factor in patients with HIV Falutz J, et al., New England Journal of Medicine, 2007 · PMID 18057338

  The pivotal trial, 412 randomised patients, that led to the 2010 approval.

• Effect of tesamorelin on visceral fat and liver fat in HIV-infected patients with abdominal fat accumulation: a randomized clinical trial Stanley TL, et al., JAMA, 2014 · PMID 25038357

  Establishes the liver fat effect alongside the visceral fat effect.

• Effects of tesamorelin on non-alcoholic fatty liver disease in HIV: a randomised, double-blind, multicentre trial Stanley TL, et al., Lancet HIV, 2019 · PMID 31611038

  The dedicated NAFLD trial with histology. This is where the off-label interest in tesamorelin for fatty liver actually comes from, and it is a real dataset rather than a forum rumour.

• EGRIFTA WR (tesamorelin) for injection - FDA prescribing information Theratechnologies, DailyMed

  Source of the under 4 percent absolute bioavailability, 0.15 hour median tmax, 4.8 L/kg volume of distribution, 11 minute half-life in healthy subjects, the 34 percent higher AUC in HIV-infected patients, and the statement that no formal human metabolism studies exist.