Tesamorelin (Egrifta)

Mechanism of Action

Tesamorelin is a synthetic analog of human growth hormone-releasing hormone (GHRH), specifically a modified GHRH(1-44) peptide with a trans-3-hexenoic acid group attached to the N-terminal tyrosine residue. This modification enhances resistance to enzymatic degradation by dipeptidyl peptidase-IV (DPP-IV) while preserving full biological activity at the GHRH receptor (GHRH-R) on anterior pituitary somatotroph cells.12

Upon binding to the GHRH receptor, tesamorelin activates the Gs-adenylyl cyclase-cAMP-PKA signaling pathway in somatotrophs, stimulating the synthesis and pulsatile release of endogenous growth hormone (GH). Unlike exogenous GH administration (which provides a constant, supraphysiologic GH level and suppresses endogenous GH pulsatility via negative feedback), tesamorelin preserves the physiologic pulsatile pattern of GH secretion, as the pituitary retains its normal regulatory mechanisms including somatostatin-mediated feedback inhibition.13 This distinction is clinically relevant: tesamorelin produces more physiologic GH and IGF-1 elevations, theoretically reducing the risk of adverse effects associated with chronic supraphysiologic GH exposure.

The primary therapeutic mechanism in HIV-associated lipodystrophy involves GH-mediated stimulation of lipolysis in visceral adipose tissue (VAT). Growth hormone activates hormone-sensitive lipase and promotes triglyceride hydrolysis, with a preferential effect on metabolically active visceral fat depots. In clinical trials, tesamorelin reduced visceral adipose tissue by approximately 15–18% over 26 weeks, while subcutaneous fat was relatively preserved.14 Additionally, tesamorelin-stimulated GH release improves lipid profiles (reducing triglycerides and non-HDL cholesterol), which may contribute to reduced cardiovascular risk in the HIV-lipodystrophy population. Emerging evidence also suggests GH-mediated effects on hepatic lipid oxidation, providing a rationale for investigation in nonalcoholic fatty liver disease (NAFLD/NASH).5

Evidence Summary

Phase 3 Pivotal Trials in HIV-Associated Lipodystrophy

The FDA approval of tesamorelin was based on two pivotal Phase 3, randomized, double-blind, placebo-controlled trials in HIV-infected adults with excess abdominal fat accumulation (lipodystrophy). In the primary pivotal trial (Falutz et al.), 412 patients were randomized to tesamorelin 2 mg or placebo subcutaneously daily for 26 weeks. Tesamorelin-treated patients demonstrated a statistically significant reduction in visceral adipose tissue (VAT) of −15.2% from baseline compared with +5.0% for placebo (p<0.001), as measured by CT scan at the L4–L5 level.1 Trunk fat was significantly reduced while limb fat was preserved, an important distinction in this population where limb fat wasting is already a concern.

In the second pivotal trial, 405 patients demonstrated consistent results: tesamorelin reduced VAT by −14.0% versus +4.6% for placebo over 26 weeks (p<0.001). Patient-reported outcomes also improved, with significant reductions in belly-image distress on the validated ABCD (Assessment of Body Change and Distress) questionnaire.4

Long-Term Extension Data

In extension studies, patients who continued tesamorelin for up to 52 weeks maintained the VAT reduction achieved during the initial treatment period. However, patients who switched from tesamorelin to placebo at week 26 experienced a return of VAT accumulation to near baseline levels by week 52, indicating that the treatment effect is not sustained after discontinuation and that ongoing therapy is required to maintain the benefit.46

Lipid and Metabolic Effects

Across trials, tesamorelin significantly reduced triglycerides (mean change −50 to −75 mg/dL), total cholesterol/HDL ratio, and non-HDL cholesterol. IGF-1 levels increased by approximately 80–100% from baseline, typically into the upper half of the age-adjusted normal range. These metabolic improvements may contribute to cardiovascular risk reduction in this population, though dedicated cardiovascular outcomes trials have not been conducted.16

Hepatic Steatosis (NAFLD/NASH)

Emerging evidence has generated interest in tesamorelin for nonalcoholic fatty liver disease, particularly in the HIV population. Stanley et al. conducted a randomized, double-blind, placebo-controlled trial in 61 HIV-infected adults with NAFLD, demonstrating that tesamorelin 2 mg daily for 12 months significantly reduced hepatic fat fraction by −4.1 percentage points (vs +0.9% for placebo; p<0.001) as measured by MR spectroscopy. Additionally, 35% of tesamorelin-treated patients had resolution of NAFLD (hepatic fat <5%) versus 4% with placebo.5 Histological analysis in a subset showed a trend toward improvement in NAFLD activity score and fibrosis stage, though the study was not powered for histologic endpoints.

Primary Uses

• HIV-associated lipodystrophy (Egrifta / Egrifta SV, 2 mg/day subcutaneous): FDA-approved for the reduction of excess abdominal fat in HIV-infected patients with lipodystrophy. Approved November 2010. This remains the only FDA-approved indication.18
• Nonalcoholic fatty liver disease / NASH (off-label, investigational): Clinical trial evidence supports tesamorelin's ability to reduce hepatic fat, particularly in HIV-positive patients with NAFLD. Off-label use is expanding, though no formal FDA indication exists for this use.5
• Age-related GH decline (off-label): Tesamorelin is used off-label in some clinical settings to address age-related decline in GH secretion (somatopause), including for body composition optimization. This use is not FDA-approved and the evidence base is limited.7

Common Stacks & Synergies

Tesamorelin is used within the context of comprehensive HIV management and may be combined with the following approaches:

• Antiretroviral therapy (ART) + Tesamorelin: All patients in clinical trials were on stable ART. Tesamorelin does not interact with antiretroviral medications, and ART continues during tesamorelin therapy. Tesamorelin addresses the metabolic consequences of ART-associated lipodystrophy.14
• Exercise + dietary modification + Tesamorelin: Lifestyle interventions are recommended as adjuncts. Resistance training may help preserve and build lean mass, complementing the visceral fat-reducing effect of tesamorelin. Aerobic exercise enhances overall metabolic benefit.
• Statin therapy + Tesamorelin: Many HIV-lipodystrophy patients have concurrent dyslipidemia. Tesamorelin reduces triglycerides and non-HDL cholesterol, which may complement statin therapy for comprehensive cardiovascular risk management.6

For detailed combination protocols and titration schedules, see our Protocols page.

Preparation & Administration

Reconstitution (Egrifta)

Original Egrifta was supplied as a lyophilized powder (1 mg per vial) requiring reconstitution with Sterile Water for Injection. Two vials were reconstituted and combined for the 2 mg dose. This formulation has been largely replaced by Egrifta SV.

Ready-to-Use Formulation (Egrifta SV)

Egrifta SV (Single Vial) is supplied as a lyophilized powder in a single 2 mg vial, reconstituted with 0.5 mL of Sterile Water for Injection provided in a prefilled syringe. This simplified formulation eliminates the need to combine two vials.

• Reconstitution: Remove the flip-off cap from the vial. Slowly inject 0.5 mL of Sterile Water for Injection into the vial. Gently roll the vial between hands for 30 seconds until the powder is dissolved. Do not shake vigorously. The reconstituted solution should be clear and colorless.
• Injection sites: Abdomen only. Rotate the injection site to different areas of the abdomen with each injection. Do not inject into scar tissue, bruises, or the navel.
• Injection technique: Clean the injection site with an alcohol swab. Pinch a fold of skin and insert the needle at a 90-degree angle. Inject the full volume slowly. Withdraw the needle and apply gentle pressure with a gauze pad if needed.
• Timing: Once daily. The label does not specify a preferred time of day, but consistent timing is recommended.

For detailed reconstitution instructions, see our Reconstitution Guide. For injection technique guidance, see our Injection Safety guide.

Side Effects & Adverse Events

Common Adverse Reactions (≥5%)

The most common adverse reactions are injection site reactions and effects related to GH-mediated fluid retention. Most adverse events are mild to moderate in severity.18

• Injection site reactions: 20–30% (erythema, pruritus, pain, irritation, swelling, hemorrhage at injection site; the most common reason for treatment discontinuation)
• Arthralgia: 10–13%
• Pain in extremity: 5–8%
• Peripheral edema: 5–8%
• Myalgia: 5–7%
• Paresthesia / hypoesthesia: 4–6%
• Nausea: 4–5%
• Pruritus (generalized): 3–5%
• Night sweats: 3–4%

Serious Adverse Events

• Glucose intolerance / new-onset diabetes: Reported in 3.3% of tesamorelin patients versus 1.3% with placebo in the pivotal trials. GH is a counter-regulatory hormone that promotes hepatic gluconeogenesis and reduces peripheral glucose uptake. Monitor fasting glucose and HbA1c.18
• Carpal tunnel syndrome: GH-mediated fluid retention and soft tissue swelling can compress the median nerve. Reported in approximately 1–2% of patients. Usually resolves with continued therapy or discontinuation.8
• Hypersensitivity reactions: Rare systemic hypersensitivity including urticaria, pruritus, and flushing have been reported. Serious anaphylactic-type reactions have not been reported in clinical trials.
• Fluid retention: May exacerbate pre-existing edema or congestive heart failure in susceptible patients.
• Anti-tesamorelin antibodies: Approximately 49% of patients developed anti-tesamorelin IgG antibodies during clinical trials. In approximately 10% of patients, these antibodies were neutralizing. The presence of antibodies did not appear to affect efficacy or safety in the studied population, but long-term implications are uncertain.8

Drug Interactions

Formal drug-drug interaction studies with tesamorelin are limited. The following interactions are based on the pharmacology of GH and known class effects:8

• Cortisone acetate and prednisone: Growth hormone stimulates the conversion of cortisone to cortisol via 11-beta-hydroxysteroid dehydrogenase type 1 (11β-HSD1). Patients on glucocorticoid replacement therapy may need dose adjustment, as tesamorelin-induced GH elevation could increase cortisol availability.8
• Antiretroviral medications: No clinically significant pharmacokinetic interactions have been observed between tesamorelin and commonly used ART regimens. Tesamorelin does not affect the metabolism of protease inhibitors, NNRTIs, or integrase inhibitors in published studies.1
• Insulin and antidiabetic medications: Tesamorelin may increase glucose levels and reduce the efficacy of antidiabetic therapy. Monitor blood glucose closely and adjust antidiabetic medications as needed.8
• CYP450 substrates: GH is known to modulate CYP450 enzyme activity, particularly CYP1A2, CYP3A4, and CYP2C19. Tesamorelin-induced GH elevation may alter the metabolism of drugs cleared by these enzymes. Clinical significance has not been established, but monitoring is recommended for narrow-therapeutic-index drugs.8

Storage & Handling

Unreconstituted Vials

• Storage: Refrigerate at 36–46°F (2–8°C). Protect from light. Do not freeze.
• Shelf life: Use before the expiration date on the vial and carton.
• Room temperature: Vials may be kept at room temperature (up to 77°F / 25°C) for up to 24 hours prior to reconstitution if needed.

After Reconstitution

• Use immediately: Administer the reconstituted solution immediately after preparation. Do not store reconstituted tesamorelin for later use.
• Do not use if the reconstituted solution is cloudy, discolored, or contains particles after gentle rolling.
• Discard: Discard any unused portion. The vials are single-use only.

Legal & Regulatory Status

• United States (FDA): Approved. Egrifta (tesamorelin for injection) approved November 2010 for the reduction of excess abdominal fat in HIV-infected patients with lipodystrophy. Egrifta SV (single-vial formulation) subsequently approved to simplify administration.8
• Canada (Health Canada): Approved. Egrifta authorized in 2015.
• European Union (EMA): Not approved. A marketing authorization application was withdrawn in 2012.
• Prescription status: Prescription only. Tesamorelin is not a controlled substance.
• Manufacturer: Theratechnologies Inc. (Montreal, QC, Canada). Distributed by EMD Serono Inc. in the United States.
• Off-label use: Off-label prescribing for NAFLD/NASH, body composition optimization, and age-related GH decline is expanding. The FDA-approved indication remains limited to HIV-associated lipodystrophy only.7

Open Questions

Despite the established role of tesamorelin in HIV-lipodystrophy, several important clinical and research questions remain:

• NAFLD/NASH indication: Phase 2 data are promising, but larger Phase 3 trials with histological endpoints are needed to pursue a formal FDA indication for NAFLD/NASH. Whether tesamorelin offers advantages over emerging GLP-1-based therapies for NASH (semaglutide, tirzepatide) remains to be determined.5
• Cardiovascular outcomes: Tesamorelin improves metabolic parameters (triglycerides, VAT, IGF-1), but no dedicated cardiovascular outcomes trial has been conducted to demonstrate reduced CV events. This is particularly relevant in the HIV population, which carries elevated cardiovascular risk.
• Long-term cancer risk: Chronic GH/IGF-1 elevation has theoretical oncogenic potential. While clinical trials and post-marketing surveillance have not shown increased malignancy rates, long-term (multi-decade) safety data are limited.8
• Durability of effect: The VAT reduction reverses upon discontinuation, raising questions about the cost-effectiveness and appropriateness of indefinite therapy. Whether intermittent dosing strategies could maintain benefit while reducing exposure is unexplored.4
• Non-HIV populations: The utility of tesamorelin in non-HIV populations with visceral adiposity, metabolic syndrome, or age-related GH decline is an area of growing off-label interest, but controlled trial data in these populations are sparse.7
• Comparison with exogenous GH: Whether the physiologic pulsatile GH release induced by tesamorelin offers meaningful clinical advantages over low-dose exogenous GH therapy in terms of efficacy or safety profile is not established by head-to-head trial data.