Ibutamoren (MK-677) is a potent long-acting, orally administered, selective non-peptide agonist of the ghrelin receptor and a growth hormone secretagogue, mimicking the growth hormone (GH)-stimulating action of the endogenous hormone ghrelin. It has been shown to increase the secretion of several hormones including GH and insulin-like growth factor 1 (IGF-1) and produces sustained increases in the plasma levels of these hormones.

MK-677 is a nonpeptide, spiro piperidine sulfonamide reported functionally indistinguishable in vitro and in vivo from the peptide GH secretagogue GHRP-6. MK-677 also activates ghrelin receptors. MK-677 is active after oral administration in animals and humans. It is reported to increase the secretion of GH, insulin-like growth factor 1 (IGF-1), and IGFBP-3 levels in children with GH deficiency. It also produces sustained increases in the plasma levels of these hormones without affecting glucose, prolactin, triiodothyronine (T3), thyroxine (T4), and insulin levels. Most studies report no effects on cortisol, but there are human and laboratory animal studies that report MK-677 can increase cortisol (use w/ caution).

MK-677, by sustaining activation of the GH-IGF-1 axis, is reported in human studies to increase lean body mass with no change in total fat mass or visceral fat and increases muscle mass and bone mineral density. As such MK-677 is under investigation as a potential treatment for reduced levels of GH and IGF-1, such as in children with growth hormone deficiency or elderly with frailty issues.

Properties:

❖ Oral form of GHRP

❖ MM = 528.7 g/mol

❖ Sequence: C27H36N4O5S

❖ Increase GH/IGF-1

❖ Non-pulsed ghrelin agonist

❖ Has a 24 hr ½ life

Benefits may include:

❖ Increase in muscle mass, and lean muscle mass

❖ Increased bone density

❖ Promotes lipolysis

❖ Improved sleep quality

❖ Improved energy

❖ Improved cellular repair

❖ Cognitive performance

❖ Increased endurance

❖ Increased IGF-1

❖ Supports joint health

Clinical Pearls:

❖ We use this w/ select patients that are in good health for short amounts of time for performance enhancement or sometimes for healing and repair after injury or surgery to help boost IGF-1 levels for healing purposes.

➢ Our protocols are typically 4-6 wks with at least 4-6 wks off in-between

■ We stay well short of the recommendation not to use > 12 wks straight without a break

■ Prolonged use can cause desensitization and involution of the receptors in the pituitary gland

■ It may also increase IGF-1 levels w/ prolonged use, and we want to be cognizant of that; so check those levels periodically if you are using MK-677 throughout the year depending on how often you are using it.

❖ We have also used it for patients who are underweight, or cachectic and need appetite stimulation

❖ Excellent and safe to build muscle if following our guidelines

❖ Take on an empty stomach, wait at least 45 minutes before eating

➢ We recommend taking before workouts (No sugar if using a pre-workout drink)

➢ Taking in the evening may cause you to wake up and eat in the middle of the night- No good

➢ It stimulates ghrelin which makes you very hungry; good for increasing your protein intake, but if you eat poorly, you may gain unwanted fat

❖ Can be used in combination with CJC 1295 / Ipamorelin for optimal results

Dosing:

❖ Males: Take 25 mg capsule PO qd x 4-6 wks (at least 4-6 wks off in between)

❖ Females: Take 12.5 mg capsule PO qd x 4 wks (at least 4 wks off in between)

Possible side effects:

❖ Increase in cortisol (by 2.3 times- have baseline and f/u labs)

❖ Increased appetite

MK-0677 (Ibutamoren)