Tabimorelin
Orally active GH secretagogue — reached Phase II clinical trials for adult GH deficiency. Distinct from MK-677 in being a true peptide-mimetic rather than a non-peptide GHS-R1a agonist.
🔬 Mechanism of Action
Tabimorelin (NN703) is an orally bioavailable growth hormone secretagogue that binds the GHS-R1a receptor on anterior pituitary somatotrophs and hypothalamic GHRH neurons. Unlike MK-677 (ibutamoren), which is a non-peptidic spiroindoline, tabimorelin is a peptide-mimetic with closer structural resemblance to natural GHRP compounds. It stimulates pulsatile GH release in a dose-dependent manner, maintaining the diurnal GH secretion pattern. Phase II trials showed significant GH and IGF-1 elevation in GH-deficient adults, but development was discontinued due to modest clinical benefit vs. established GH replacement and the emergence of more potent oral secretagogues.
Source: PMID: 11401563
📜Background & History
Tabimorelin (NN703) was developed by Novo Nordisk as a potential oral alternative to GH injections for growth hormone deficient adults. It entered Phase II clinical trials in the early 2000s showing dose-dependent GH elevation, but the magnitude of IGF-1 increase and clinical endpoints were modest compared to established GH replacement therapy. Development was discontinued, but tabimorelin remains an important reference compound in the growth hormone secretagogue field.
🎯 Research Use Cases
- ✓GH deficiency research
- ✓Oral GH secretagogue development
- ✓GHS-R1a pharmacology research
💉 Dosing Protocol
| Typical Dose | 0.5-10 mg/day (oral) |
| Frequency | 1× daily (oral) |
| Half-Life | ~2 hours |
⚠️Safety & Considerations
Oral dosing well-tolerated in Phase II. Mild transient increases in cortisol, prolactin, and appetite were reported. Development discontinued — research compound only. Similar drug-drug interaction profile to other ghrelin mimetics.
⚡Interactions & Contraindications
May increase cortisol and prolactin transiently. Similar drug interaction profile to other ghrelin mimetics — caution with insulin-sensitizing agents due to potential GH-mediated insulin resistance.
🔗Synergies & Common Stacks
Both are oral GHS-R1a agonists. MK-677 is a non-peptide while tabimorelin is a peptide-mimetic — useful for comparing structural class effects on GH secretion patterns.
Tabimorelin and GHRP-2 share the GHS-R1a mechanism. Comparing oral (tabimorelin) vs injectable (GHRP-2) routes.