COMMON INITIAL DOSING REGIMENS

• A typical starting dose is 10–25 mg taken orally once daily, usually at bedtime to mimic the natural nocturnal peak in GH secretion. Higher doses (up to 50 mg daily) may be prescribed based on individual goals and tolerability, particularly in athletic or recovery contexts.

MECHANISM OF ACTION

• Ibutamoren is a selective agonist of the ghrelin receptor (growth hormone secretagogue receptor, GHSR). By stimulating GHSR, it promotes the release of GH from the pituitary gland, which subsequently raises circulating IGF-1 levels. This dual effect enhances protein synthesis, supports muscle and tissue repair, and improves metabolism. Unlike direct GH administration, ibutamoren does not suppress endogenous GH production, allowing for sustained physiological effects.

• A unique feature of ibutamoren is its stimulation of appetite due to ghrelin receptor activation, which may be beneficial for patients with cachexia but potentially undesirable for those focusing on weight management.

COMMON SIDE EFFECTS

• Metabolic: Increased appetite and mild weight gain, which may be advantageous or a drawback depending on therapeutic goals. Transient hyperglycemia or insulin resistance can occur with prolonged use.

• Neurological: Vivid dreams, drowsiness, or mild lethargy.

• Fluid Retention: Peripheral edema, particularly in the lower extremities, is relatively common and dose-dependent.

• Musculoskeletal: Joint pain or stiffness may occur, especially in older adults.

• Severe Effects: Long-term use may potentially exacerbate latent diabetes or increase the risk of metabolic syndrome. Monitoring is crucial for at-risk patients.

CONTRAINDICATIONS

• Absolute: Known hypersensitivity to ibutamoren or its components.

• Relative: Ibutamoren should be used cautiously in individuals with diabetes, insulin resistance, or significant cardiovascular conditions due to its effects on glucose metabolism and potential fluid retention. Patients with a history of cancer should consult their physician, as prolonged GH elevation could theoretically stimulate tumor growth.

COMPARISON WITH OTHER HGH SUPPORT MEDICATIONS

• Ibutamoren vs. CJC-1295: Ibutamoren’s oral administration provides convenience over CJC-1295’s subcutaneous route. However, CJC-1295 offers more sustained GH release and is less likely to cause appetite stimulation, making it preferable for fat loss and long-term GH optimization.

• Ibutamoren vs. Ipamorelin: Ibutamoren’s mechanism of action involves ghrelin receptor activation, leading to increased appetite, while ipamorelin stimulates GH release without appetite effects. Ipamorelin is more suitable for patients who wish to avoid weight gain or glucose dysregulation.

• Ibutamoren vs. Sermorelin: Sermorelin requires daily subcutaneous injections, whereas ibutamoren is taken orally. Sermorelin’s effects are more localized to GH release, while ibutamoren provides broader metabolic impacts through IGF-1 elevation.

• Ibutamoren vs. Tesamorelin: Tesamorelin’s effects are highly targeted toward reducing visceral adiposity and improving lipid profiles, whereas ibutamoren has a more systemic impact on body composition and recovery.

MORE INFORMATION

• FDA Safety Data Sheet not available

• Sigalos JT, Pastuszak AW. The Safety and Efficacy of Growth Hormone Secretagogues. Sex Med Rev. 2018 [PubMed link]

• Liu H, Sun D, Myasnikov A, et al. Structural basis of human ghrelin receptor signaling by ghrelin and the synthetic agonist ibutamoren. Nat Commun. 2021 [PubMed link]

• Murphy MG, Plunkett LM, Gertz BJ, et al. MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism. J Clin Endocrinol Metab. 1998 [PubMed link]

• Sinha DK, Balasubramanian A, Tatem AJ, et al. Beyond the androgen receptor: the role of growth hormone secretagogues in the modern management of body composition in hypogonadal males. Transl Androl Urol. 2020 [PubMed Link]