MK-677 (Ibutamoren) vs TB-500

A detailed comparison to help you understand the differences and choose the right peptide for your research goals.

MK-677 (Ibutamoren)

MK-677, also known as Ibutamoren, is an orally active growth hormone secretagogue. Unlike peptides, it can be taken orally and has a long half-life, providing 24-hour GH elevation.

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TB-500

Thymosin Beta-4 (TB-500) is a naturally occurring peptide present in almost all human and animal cells. It plays a crucial role in tissue repair and regeneration.

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Side-by-Side Comparison

Aspect	MK-677 (Ibutamoren)	TB-500
Dose Range	10 mg–25 mg	2 mg–2.5 mg
Frequency	1x daily	Less than daily
Cycle Length	8–24 weeks	4–8 weeks
Route	oral	subcutaneous
Mechanism	Acts as a potent, selective agonist of the ghrelin receptor (GHS-R1a). Increases GH and IGF-1 levels without affecting cortisol. Mimics ghrelin's GH-releasing effects.	TB-500 promotes cell migration and differentiation, regulates actin (a cell-building protein), and reduces inflammation. It supports the formation of new blood vessels and wound healing.
Typical Dosage	Typical dosing: 10-25mg taken orally once daily. Often taken at night due to sleep benefits and appetite increase.	Research protocols typically use 2-2.5mg twice weekly during the loading phase, followed by maintenance dosing of 2mg every 2 weeks.
Administration	Oral administration (capsule or liquid). Can be taken with or without food. Long half-life allows once-daily dosing.	Administered via subcutaneous or intramuscular injection. Some protocols suggest injection near injury sites.
Side Effects	Increased appetite and water retention are most common. May cause lethargy, vivid dreams, and mild numbness. Can affect blood glucose and insulin sensitivity.	May cause temporary fatigue, headache, or localized irritation at injection sites.
Best For	Muscle Growth Fat Loss Recovery & Healing Sleep Quality	Muscle Growth Recovery & Healing