Tesamorelin is a synthetic analogue of growth hormone releasing hormone (GHRH) developed by Theratechnologies and approved in 2010 for HIV-associated lipodystrophy. It is one of the few GHRH analogues to reach the regulatory finish line, and its research record is informative for the broader class. This article maps the mechanism and the published data.
Structure and modification
Tesamorelin is GHRH(1-44) with a single N-terminal modification — a trans-3-hexenoic acid attached to the alpha-amino group of the N-terminal tyrosine. This modification confers resistance to dipeptidyl peptidase IV (DPP-IV) degradation, extending the in vivo half-life from minutes to approximately 25-35 minutes.
Mechanism — pulsatile GH stimulation
Like native GHRH, tesamorelin binds the GHRH receptor on pituitary somatotrophs and triggers growth hormone release. The DPP-IV resistance means the stimulus persists long enough to drive a meaningful pulse without being immediately degraded. Critically, the pulse is dependent on residual somatotroph function — tesamorelin requires a functional pituitary to work.
Why pulsatile GH matters
Endogenous GH release is naturally pulsatile. Sustained GH elevation (as from exogenous recombinant GH administration) has different metabolic effects than the pulsatile pattern from natural release. Tesamorelin preserves pulsatility — the pituitary releases GH in bursts that match the body’s regulatory pattern rather than overriding it.
Trial data — visceral fat reduction
The pivotal trials (Falutz et al., NEJM 2007, AIDS 2008) examined tesamorelin in HIV-positive adults with excess visceral adipose tissue (VAT). Results:
| Endpoint | Tesamorelin (26 weeks) | Placebo |
|---|---|---|
| VAT reduction (CT scan) | ~18% | +2% |
| IGF-1 levels | Restored to upper normal range | Unchanged |
| Lipid profile | Improved triglycerides | Unchanged |
The visceral fat reduction was preferential — subcutaneous fat was largely preserved while abdominal visceral fat reduced. This is mechanistically consistent with GH’s known lipolytic effect on visceral adipose.
How tesamorelin differs from sermorelin and CJC-1295
| Compound | Sequence | Half-life | Clinical record |
|---|---|---|---|
| Sermorelin | GHRH(1-29) | ~10 min | Older, less stable |
| CJC-1295 (no DAC) | GHRH(1-29) with 4 substitutions | ~30 min | Research-grade |
| CJC-1295 (with DAC) | + albumin linker | ~8 days | Research-grade |
| Tesamorelin | GHRH(1-44) + N-terminal mod | ~30 min | FDA-approved |
See our sermorelin vs CJC-1295 article for the analogue comparison.
Side effect profile
- Injection site reactions (most common)
- Joint pain and stiffness (related to GH-mediated fluid retention)
- Mild hyperglycaemia in some subjects
- Rare allergic reactions
Why visceral fat specifically
Visceral adipose tissue is metabolically distinct from subcutaneous fat. It has higher lipolytic activity, expresses different adipokines, and is more responsive to GH. The IGF-1 axis preferentially mobilises VAT under elevated tone. This is why a GHRH analogue produces preferential VAT reduction.
Research handling
Tesamorelin is supplied lyophilised. Reconstitution in bacteriostatic water at 1–2 mg/mL is standard. Refrigerated reconstituted tesamorelin retains potency for approximately 4 weeks. Avoid freeze-thaw.
Chempeptides supplies HPLC-verified tesamorelin with batch CoA — see the catalogue.
Research use only.