--- title: "MK-677 (Ibutamoren): Benefits, Dosage & Side Effects" description: "MK-677 (ibutamoren) is an oral ghrelin-receptor agonist, not a peptide. How it works, what the two-year trial found, and side effects on glucose and the heart." canonical: "https://www.vitalsvault.com/peptides/mk-677" last-updated: 2026-08-22 --- # MK-677 (Ibutamoren): Benefits, Dosage & Side Effects > MK-677 (ibutamoren) is an oral ghrelin-receptor agonist, not a peptide. How it works, what the two-year trial found, and side effects on glucose and the heart. ![A Tamil man, 62, slim, thinning white hair, round glasses, stretches a hamstring on a woven living room rug with a towel in his hands, eyes down,…](https://www.vitalsvault.com/_next/image?url=%2Fpublic-v3%2Fshoot%2Fpeptides%2Fpep-mk677.webp&w=3840&q=75&dpl=shadow-production-f0162cb4d465-40992538108-1) Peptide Guide · Growth hormone and muscle # MK-677 Ibutamoren, MK-0677 MK-677 shows up in every conversation about growth hormone peptides, yet chemically it sits outside the family. It is a pill built to mimic the peptide GHRP-6, and only later recognized as working on the receptor of the hunger hormone ghrelin. [Get early access to peptide care](https://www.vitalsvault.com/peptides-waitlist)[Start with 120+ lab tests · $99](https://www.vitalsvault.com/labs#plans) Free to join · One email when peptide care opens · Most lab results in 3–5 business days Studied forGrowth hormone and IGF-1 levels, lean mass and frailty in older adults EvidenceHuman trials Taken asOral, in clinical trials Studied forGrowth hormone and IGF-1 levels, lean mass and frailty in older adults EvidenceHuman trials Taken asOral, in clinical trials ## MK-677, in short MK-677 (ibutamoren) is an oral small-molecule drug, not a peptide, that mimics ghrelin and activates the ghrelin receptor (GHS-R1a), raising growth hormone and IGF-1. Trials of up to two years in older adults found more lean mass but not more strength or function, along with more appetite, higher fasting glucose and lower insulin sensitivity. A hip fracture trial raised heart failure concerns. Medically reviewed by [Robert Lufkin, MD (opens in a new tab)](https://www.robertlufkinmd.com/) Chief Medical Officer, Vitals Vault · Updated October 29, 2026 · 15 sources ## At a glance Human trials TypeSmall-molecule ghrelin mimetic, not a peptide[3](https://www.vitalsvault.com/peptides/mk-677#source-ghigo-1997) TargetGhrelin receptor (GHS-R1a) on the pituitary and hypothalamus[1](https://www.vitalsvault.com/peptides/mk-677#source-howard-1996) Taken asOral, in clinical trials[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008) Studied forGrowth hormone, IGF-1 and lean mass in older adults[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008)[12](https://www.vitalsvault.com/peptides/mk-677#source-adunsky-2011) Main effects seenMore appetite, higher fasting glucose, lower insulin sensitivity, higher cortisol[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008) FDA statusNot approved. FDA cites heart failure risk[13](https://www.vitalsvault.com/peptides/mk-677#source-fda-bulks)[12](https://www.vitalsvault.com/peptides/mk-677#source-adunsky-2011) SportGrowth hormone secretagogues are prohibited by WADA[15](https://www.vitalsvault.com/peptides/mk-677#source-wada) ## Before you consider MK-677 - Safety Trials in people found more appetite, higher fasting glucose and lower insulin sensitivity. A hip fracture trial stopped early for a heart failure signal.[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008)[12](https://www.vitalsvault.com/peptides/mk-677#source-adunsky-2011) [Side effects and safety](https://www.vitalsvault.com/peptides/mk-677#safety) - Legal status Not FDA approved. FDA lists it as a compounding risk because of heart failure, and it is not covered by the October 2026 policy.[13](https://www.vitalsvault.com/peptides/mk-677#source-fda-bulks)[14](https://www.vitalsvault.com/peptides/mk-677#source-ncpa) [FDA status](https://www.vitalsvault.com/peptides/mk-677#fda-status) - How it’s taken It was taken by mouth in the trials. It is not made as an approved medicine, and research-use-only products are not made for people.[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008)[14](https://www.vitalsvault.com/peptides/mk-677#source-ncpa) [Forms and dosage](https://www.vitalsvault.com/peptides/mk-677#how-taken) ## How does MK-677 work? MK-677 is a pill that copies the hunger hormone and tells the body to make more growth hormone. - ### Acts like a hunger hormone It switches on the same brain-gland receptor that the hunger hormone ghrelin uses.[1](https://www.vitalsvault.com/peptides/mk-677#source-howard-1996)[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008) - ### Growth hormone goes up The pituitary gland responds by releasing more growth hormone in pulses.[1](https://www.vitalsvault.com/peptides/mk-677#source-howard-1996)[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008) - ### Side effects follow Because it copies a hunger signal, appetite rises. Cortisol rose and insulin sensitivity fell in the two-year trial.[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008) ## MK-677 benefits: what it is studied for These are results from human trials, including a two-year one. The findings are mixed, and none show better strength. 1. Human study01 ### Growth hormone and IGF-1 In 65 healthy adults aged 60 to 81, daily MK-677 for a year raised growth hormone and IGF-1 to the range of healthy young adults.[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008) 2. Human study02 ### Fat-free mass Fat-free mass rose by 1.1 kg on MK-677 and fell by 0.5 kg on placebo over a year. Strength and function did not change.[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008) 3. Human study03 ### Recovery after hip fracture In 123 patients, gait speed improved over 24 weeks, but most other function measures did not. The trial stopped early because of a heart failure signal.[12](https://www.vitalsvault.com/peptides/mk-677#source-adunsky-2011) ## What the research shows Human trials 1. 1 · Cells in a labNot cited This guide cites no findings at this level. Shows a mechanism 2. 2 · AnimalsNot cited This guide cites no findings at this level. Shows an effect in a body 3. 3 · People Studied A two-year trial in 65 older adults raised growth hormone and added lean mass, but not strength. A hip fracture trial stopped early for heart failure.[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008)[12](https://www.vitalsvault.com/peptides/mk-677#source-adunsky-2011) Shows it works in people The 2008 Annals of Internal Medicine trial is the main source. It found more growth hormone, IGF-1 and fat-free mass, but not more strength or function. The hip fracture trial reached the same split between hormone levels and function, and ended early because of the heart failure signal FDA cites.[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008)[12](https://www.vitalsvault.com/peptides/mk-677#source-adunsky-2011)[13](https://www.vitalsvault.com/peptides/mk-677#source-fda-bulks) The full guide to MK-677 9 min read · Medically reviewed by Robert Lufkin, MD ## Why MK-677 can be swallowed when growth hormone peptides are injected Most growth hormone peptides are given by injection, because the gut breaks peptides down much as it breaks down any other protein. The compound people mention most often alongside them comes as a capsule. MK-677 gets away with that because, chemically, it sits outside the peptide family altogether. It is a small synthetic molecule that Merck chemists built to survive the trip through the gut. The idea started with a peptide. By the early 1990s, GHRP-6 reliably released growth hormone, and Merck wanted something that could be swallowed. In 1993 its scientists reported a first non-peptide molecule that behaved as a mimic of GHRP-6 and worked alongside GHRH. In 1995 they described a more potent successor, coded L-163,191 and then MK-0677, that raised growth hormone in dogs when given by mouth. The 1995 paper called it mechanistically indistinguishable from GHRP-6. In dogs it released growth hormone without significant effects on aldosterone, LH, thyroxine or prolactin, with only modest increases in cortisol, and Merck selected it for clinical studies. Its drug name is ibutamoren mesylate. A year later, a Merck team cloned the receptor these compounds act on, which turned out to be the receptor for ghrelin, a stomach hormone discovered in 1999. Being oral changed what could be studied. Peptide secretagogues were studied mainly in short experiments, some with repeated dosing, while MK-677 went into trials lasting a year or two and enrolling hundreds of patients, including a two-year trial and a 563-person Alzheimer’s trial. That makes it one of the clearest windows onto what raising growth hormone for a long time actually does.[4](https://www.vitalsvault.com/peptides/mk-677#source-smith-1993)[5](https://www.vitalsvault.com/peptides/mk-677#source-patchett-1995)[1](https://www.vitalsvault.com/peptides/mk-677#source-howard-1996)[2](https://www.vitalsvault.com/peptides/mk-677#source-kojima-1999)[12](https://www.vitalsvault.com/peptides/mk-677#source-adunsky-2011)[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008)[10](https://www.vitalsvault.com/peptides/mk-677#source-sevigny-2008) ## How MK-677 works: stronger pulses, more IGF-1 MK-677 binds the growth hormone secretagogue receptor, GHS-R1a, on the pituitary and in the hypothalamus, the same receptor ghrelin and the GHRP peptides use. The pituitary answers with more growth hormone, released in pulses as it normally is. Growth hormone then signals the liver to make IGF-1, which carries much of its effect on tissues. A 1997 University of Virginia study showed both the power and the limits of that chain. Nine young men with severe growth hormone deficiency, all treated with growth hormone as children, took MK-677 or placebo for four days, with blood drawn every 20 minutes for 24 hours before and after. Average 24-hour growth hormone rose by about 80 percent and IGF-1 rose in every subject. The detail worth noticing is who responded most. The growth hormone rise was largest in the men who were least deficient to begin with. MK-677 amplifies a pituitary’s own output, so it needs a pituitary with something left to amplify. In healthy older adults with working pituitaries, a later trial found it brought growth hormone and IGF-1 up to the levels of healthy young adults. The same receptor carries other messages. It drives appetite, it can nudge the stress axis, and growth hormone itself opposes insulin. In the four-day study, fasting and after-meal insulin and after-meal glucose rose, an early sign of the metabolic trade-off the longer trials would confirm.[1](https://www.vitalsvault.com/peptides/mk-677#source-howard-1996)[6](https://www.vitalsvault.com/peptides/mk-677#source-chapman-1997)[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008) ## MK-677 benefits for muscle and body composition: the short trials The cleanest early test of MK-677 as an anabolic drug came from Merck in 1998. Eight healthy volunteers aged 24 to 39 followed a strict low-calorie diet for two 14-day periods, taking MK-677 or placebo during the second week of each. Dieting alone made them lose body protein, measured as nitrogen lost in urine. MK-677 reversed that. During the treatment week, average nitrogen balance was slightly positive on the drug and clearly negative on placebo, meaning the body held on to protein despite the calorie cut. IGF-1, which had fallen with dieting, rose back above its starting level on MK-677, and the volunteers had no clinically significant adverse effects. A Swedish trial the same year tried it in 24 obese men aged 18 to 50 for eight weeks. IGF-1 rose about 40 percent and fat-free mass increased, but no significant change in total or visceral fat was detected. Resting metabolic rate rose at two weeks and was no longer different at eight. An oral glucose tolerance test showed worse glucose handling at both checkpoints, while the cortisol rise was only transient. Read together, the short trials show an anabolic, protein-sparing drug with no demonstrated fat loss, and the obesity trial found blood sugar harder to control. The longer studies that followed measured different outcomes, but those threads keep surfacing.[8](https://www.vitalsvault.com/peptides/mk-677#source-murphy-1998)[9](https://www.vitalsvault.com/peptides/mk-677#source-svensson-1998) ## MK-677 in older adults: what the two-year trial found The landmark study appeared in Annals of Internal Medicine in 2008. A University of Virginia team randomized 65 healthy adults aged 60 to 81 to daily MK-677 or placebo in a two-year, double-blind trial. The question was whether restoring youthful growth hormone could stop the slow loss of muscle that leads to frailty. The hormones did exactly what was hoped. Growth hormone and IGF-1 rose to the range of healthy young adults. Over a year, fat-free mass rose by 1.1 kg on MK-677 and fell by 0.5 kg on placebo. Body weight rose by 2.7 kg on the drug against 0.8 kg on placebo, and some of the gap was fat, since limb fat rose more on MK-677 while abdominal visceral fat did not differ. Then came the result that matters most. The extra fat-free mass did not translate into any change in strength or function. The authors noted their trial was not large or long enough to judge functional outcomes, which is fair, but the people who took the drug for a year were not measurably stronger. Side effects were mostly mild. Appetite rose and settled within a few months, and mild leg swelling and muscle pain came and went. Fasting glucose rose by about 5 mg/dL, insulin sensitivity fell and cortisol rose, while LDL cholesterol dipped slightly and bone mineral density changed in a way consistent with faster remodeling. Two-year exploratory analyses confirmed the one-year picture.[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008) ## MK-677 and sleep: one small study with a striking result Growth hormone and deep sleep are tightly linked, and a 1997 Brussels study asked whether MK-677 would change sleep itself. Eight young adults aged 18 to 30 took MK-677 or placebo for three 7-day periods in a crossover design, and six adults aged 65 to 71 took two 14-day courses of the drug, compared with their own baseline. In the young adults, the higher dose increased stage IV sleep, the deepest stage, by about 50 percent and REM sleep by more than 20 percent compared with placebo. Nights with abnormal sleep patterns fell from 42 percent to 8 percent. In the older adults, REM sleep rose by nearly half and arrived sooner after falling asleep. The authors suggested MK-677 might improve sleep quality and correct the age-related fall in growth hormone at the same time. The study was small and short, though, and the abstracts of the long trials cited here do not report sleep outcomes, so this remains a promising early signal.[7](https://www.vitalsvault.com/peptides/mk-677#source-copinschi-1997) ## Hip fracture and heart failure: the trial that stopped early Most older adults admitted with a broken hip lose function, and earlier studies hinted MK-677 might help recovery. A multicenter phase IIb trial tested that in 123 elderly hip fracture patients, 62 on MK-677 and 61 on placebo, for 24 weeks. IGF-1 rose by about 51 ng/mL over placebo, so the drug engaged its target. Gait speed improved modestly. Stair-climbing power was not significantly better, several other performance measures showed no improvement, and a trend toward fewer falls did not reach significance. The trial was stopped early because of a safety signal of congestive heart failure in a limited number of patients. The investigators concluded that MK-677 has an unfavorable safety profile in this population, and FDA’s compounding page cites this trial for its heart failure concern. Why heart failure would appear is not settled. One plausible link, and it is only a hypothesis, is fluid retention, since growth hormone holds salt and water and leg swelling was common even in healthy older adults on MK-677. In frail patients with less cardiac reserve, a little extra fluid can matter a great deal.[12](https://www.vitalsvault.com/peptides/mk-677#source-adunsky-2011)[13](https://www.vitalsvault.com/peptides/mk-677#source-fda-bulks)[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008) Know your baseline before any peptide 120+ lab tests at Quest Diagnostics, every result reviewed by a licensed clinician. Most results in 3–5 business days. A baseline today gives your clinician something to compare against if you start MK-677 later. [Start with 120+ lab tests · $99](https://www.vitalsvault.com/labs#plans)[Get early access to peptide care](https://www.vitalsvault.com/peptides-waitlist) Full refund before your blood draw · No membership ## The number moved, the outcome did not The largest MK-677 trial cited here was not about muscle. In animals, IGF-1 helps clear beta-amyloid, the protein that builds up in Alzheimer’s disease, and IGF-1 levels fall with age and fall further in Alzheimer’s. Merck randomized 563 people with mild to moderate Alzheimer’s to MK-677 or placebo for 12 months. IGF-1 rose 60 percent within six weeks and 73 percent by a year. On all four measures of thinking, daily function and overall change, the MK-677 group did no better than placebo. The authors noted that despite clear evidence the drug engaged its target, it did not slow the disease. Line the big trials up and the pattern is hard to miss. In healthy older adults, lean mass rose and strength did not. After hip fracture, IGF-1 rose and most function did not. In Alzheimer’s, IGF-1 rose by nearly three-quarters and the disease went on. Each time, MK-677 did precisely what it was designed to do on the lab report. That is the most useful thing MK-677 can teach anyone interested in growth hormone. IGF-1 is a messenger. Raising it tells tissues to grow, but whether they can depends on loading, protein, sleep, insulin sensitivity and the disease in front of you. A rising IGF-1 confirms the drug is working on its receptor, and it tells you very little about whether you are getting better.[10](https://www.vitalsvault.com/peptides/mk-677#source-sevigny-2008)[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008)[12](https://www.vitalsvault.com/peptides/mk-677#source-adunsky-2011) ## MK-677 side effects and safety The everyday side effects come straight from the biology. Appetite rises, usually settling over a few months. Mild leg swelling and muscle pain are common early on, and body weight climbs, partly as fat. Blood sugar is the consistent metabolic cost. In the two-year trial fasting glucose rose by about 5 mg/dL and insulin sensitivity fell. The eight-week obesity trial found worse glucose tolerance, and even the four-day study saw insulin and after-meal glucose rise. Cortisol results vary by study, from no change in some to a modest, lasting rise in the two-year trial. The serious concern is the heart. The hip fracture trial stopped early for a congestive heart failure signal, and FDA’s compounding page lists ibutamoren mesylate for both 503A and 503B because of the potential for congestive heart failure in certain patients. Anyone with heart failure, heart disease or leg swelling, diabetes or prediabetes, a personal history of cancer, a pregnancy or a place in tested sport should take MK-677 to a clinician as a question first.[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008)[9](https://www.vitalsvault.com/peptides/mk-677#source-svensson-1998)[6](https://www.vitalsvault.com/peptides/mk-677#source-chapman-1997)[8](https://www.vitalsvault.com/peptides/mk-677#source-murphy-1998)[12](https://www.vitalsvault.com/peptides/mk-677#source-adunsky-2011)[13](https://www.vitalsvault.com/peptides/mk-677#source-fda-bulks) ## Which labs matter with MK-677, and why Each human MK-677 study here that measured glucose handling found it got worse, though none establishes a validated monitoring protocol. As general baseline context for a clinician, fasting glucose, fasting insulin and HbA1c describe that system, and HbA1c gives a three-month average that one morning reading cannot. Cortisol findings varied across studies, rising modestly in the two-year trial and only briefly in the obesity trial, so a single value is context rather than a routine check. A clinician weighing MK-677 will also want your heart history, blood pressure and any swelling on the record. This is how Vitals Vault approaches anything in the growth hormone family. A blood panel at Quest Diagnostics comes first, a licensed clinician reviews your results and history and decides what, if anything, fits, and any course ends with a retest of the same markers.[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008)[9](https://www.vitalsvault.com/peptides/mk-677#source-svensson-1998)[6](https://www.vitalsvault.com/peptides/mk-677#source-chapman-1997)[12](https://www.vitalsvault.com/peptides/mk-677#source-adunsky-2011) ## Where MK-677 stands in 2026 MK-677 is not an FDA-approved drug. FDA’s April 2026 compounding page lists ibutamoren mesylate for both 503A and 503B, citing the potential for congestive heart failure. The enforcement discretion FDA granted on October 29, 2026 covers six peptides, and MK-677 is not among them. In sport, growth hormone secretagogues fall in the S2 class of the World Anti-Doping Agency’s Prohibited List, which applies in and out of competition. Capsules and liquids sold online for research use only are not made for people and fall outside FDA’s policy.[13](https://www.vitalsvault.com/peptides/mk-677#source-fda-bulks)[14](https://www.vitalsvault.com/peptides/mk-677#source-ncpa)[15](https://www.vitalsvault.com/peptides/mk-677#source-wada) ## What this means for you MK-677 is an oral ghrelin mimic with a longer human trial record than most growth hormone secretagogues. It reliably raises growth hormone and IGF-1 and adds lean mass. In trials, it did not make people stronger, improve most measures of function after a fracture or slow Alzheimer’s. It also raises appetite and blood sugar, and in frail older patients it carried a heart failure signal. If MK-677 interests you, look past the IGF-1 number. The better question is what result you actually want, whether strength, sleep, body composition or something else, and whether anything in the trials shows MK-677 moving that result rather than just the hormone.[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008)[12](https://www.vitalsvault.com/peptides/mk-677#source-adunsky-2011)[10](https://www.vitalsvault.com/peptides/mk-677#source-sevigny-2008) Know your baseline before any peptide 120+ lab tests at Quest Diagnostics, every result reviewed by a licensed clinician. Most results in 3–5 business days. A baseline today gives your clinician something to compare against if you start MK-677 later. [Start with 120+ lab tests · $99](https://www.vitalsvault.com/labs#plans)[Get early access to peptide care](https://www.vitalsvault.com/peptides-waitlist) Full refund before your blood draw · No membership ## What to expect with MK-677 A responsible start is a health history that includes your heart, a baseline blood panel and a clinician’s view on whether anything in the growth hormone family fits. MK-677 is not part of the October 2026 compounding pathway, so for most people that conversation is about trade-offs and alternatives. On timing, the trials describe a clear sequence. Growth hormone and IGF-1 rose within days, sleep changes appeared within a week in the small sleep study, appetite rose early and settled over a few months, and fat-free mass changes were measured at 12 months. Glucose changes showed up as early as the first week and persisted.[6](https://www.vitalsvault.com/peptides/mk-677#source-chapman-1997)[7](https://www.vitalsvault.com/peptides/mk-677#source-copinschi-1997)[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008)[9](https://www.vitalsvault.com/peptides/mk-677#source-svensson-1998)[14](https://www.vitalsvault.com/peptides/mk-677#source-ncpa) ## Key MK-677 studies - Chapman et al., 1997[6](https://www.vitalsvault.com/peptides/mk-677#source-chapman-1997) Double-blind rising-dose study · 9 young men with severe growth hormone deficiency 24-hour growth hormone up about 80 percent and IGF-1 up in all; largest rise in the least deficient Limits: Four days, small - Copinschi et al., 1997[7](https://www.vitalsvault.com/peptides/mk-677#source-copinschi-1997) Placebo-controlled crossover (young); active courses vs baseline (older) · 8 young and 6 older adults About 50 percent more deepest-stage sleep and over 20 percent more REM in young adults Limits: Small, one to two weeks - Murphy et al., 1998[8](https://www.vitalsvault.com/peptides/mk-677#source-murphy-1998) Placebo-controlled crossover · 8 healthy dieting volunteers Turned diet-induced protein loss into a slight positive balance Limits: One week of treatment - Svensson et al., 1998[9](https://www.vitalsvault.com/peptides/mk-677#source-svensson-1998) Randomized, placebo-controlled · 24 obese men, 8 weeks IGF-1 up about 40 percent and fat-free mass up; no significant fat change; glucose tolerance worse Limits: Short, men only - Nass et al., 2008[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008) Two-year randomized, placebo-controlled · 65 healthy adults aged 60 to 81 Fat-free mass up 1.1 kg versus a 0.5 kg loss; no change in strength or function Limits: Too small to judge function, by the authors’ own account - Sevigny et al., 2008[10](https://www.vitalsvault.com/peptides/mk-677#source-sevigny-2008) 12-month randomized, placebo-controlled · 563 people with mild to moderate Alzheimer’s IGF-1 up about 73 percent with no effect on disease progression Limits: Alzheimer’s population only - Adunsky et al., 2011[12](https://www.vitalsvault.com/peptides/mk-677#source-adunsky-2011) Phase IIb randomized, placebo-controlled · 123 older adults after hip fracture IGF-1 up and gait speed better, most other function not; stopped early for heart failure Limits: Ended early Key studies on MK-677 | Study | Design | Who | What it found | Limits | | --- | --- | --- | --- | --- | | Chapman et al., 1997[6](https://www.vitalsvault.com/peptides/mk-677#source-chapman-1997) | Double-blind rising-dose study | 9 young men with severe growth hormone deficiency | 24-hour growth hormone up about 80 percent and IGF-1 up in all; largest rise in the least deficient | Four days, small | | Copinschi et al., 1997[7](https://www.vitalsvault.com/peptides/mk-677#source-copinschi-1997) | Placebo-controlled crossover (young); active courses vs baseline (older) | 8 young and 6 older adults | About 50 percent more deepest-stage sleep and over 20 percent more REM in young adults | Small, one to two weeks | | Murphy et al., 1998[8](https://www.vitalsvault.com/peptides/mk-677#source-murphy-1998) | Placebo-controlled crossover | 8 healthy dieting volunteers | Turned diet-induced protein loss into a slight positive balance | One week of treatment | | Svensson et al., 1998[9](https://www.vitalsvault.com/peptides/mk-677#source-svensson-1998) | Randomized, placebo-controlled | 24 obese men, 8 weeks | IGF-1 up about 40 percent and fat-free mass up; no significant fat change; glucose tolerance worse | Short, men only | | Nass et al., 2008[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008) | Two-year randomized, placebo-controlled | 65 healthy adults aged 60 to 81 | Fat-free mass up 1.1 kg versus a 0.5 kg loss; no change in strength or function | Too small to judge function, by the authors’ own account | | Sevigny et al., 2008[10](https://www.vitalsvault.com/peptides/mk-677#source-sevigny-2008) | 12-month randomized, placebo-controlled | 563 people with mild to moderate Alzheimer’s | IGF-1 up about 73 percent with no effect on disease progression | Alzheimer’s population only | | Adunsky et al., 2011[12](https://www.vitalsvault.com/peptides/mk-677#source-adunsky-2011) | Phase IIb randomized, placebo-controlled | 123 older adults after hip fracture | IGF-1 up and gait speed better, most other function not; stopped early for heart failure | Ended early | ## MK-677 myths and evidence - ### MK-677 is a peptide It is a small non-peptide molecule that Merck designed to be taken by mouth as a mimic of the peptide GHRP-6. It acts on the same ghrelin receptor, which is why it gets grouped with the peptides.[5](https://www.vitalsvault.com/peptides/mk-677#source-patchett-1995)[4](https://www.vitalsvault.com/peptides/mk-677#source-smith-1993) - ### MK-677 makes you stronger In the two-year trial in older adults it added about a kilogram of fat-free mass, but strength and function did not change. After hip fracture, most function measures did not improve either.[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008)[12](https://www.vitalsvault.com/peptides/mk-677#source-adunsky-2011) - ### MK-677 burns fat No significant change in total or visceral fat was seen in obese men over eight weeks, and in older adults body weight rose 2.7 kg in a year, with more limb fat than on placebo.[9](https://www.vitalsvault.com/peptides/mk-677#source-svensson-1998)[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008) - ### If your IGF-1 goes up, MK-677 is working for you In 563 people with Alzheimer’s, IGF-1 rose about 73 percent and the disease progressed just as it did on placebo. A higher IGF-1 shows the drug reached its target. On its own, it says nothing about outcomes.[10](https://www.vitalsvault.com/peptides/mk-677#source-sevigny-2008) Know your baseline first 120+ lab tests at Quest, every result reviewed by a licensed clinician. Most results in 3–5 business days. [Start with 120+ lab tests · $99](https://www.vitalsvault.com/labs#plans) ## How is MK-677 taken? MK-677 was given by mouth in the trials. It is not made as an FDA-approved medicine. Products sold online for research use only are not made for people and are not covered by FDA’s October 2026 policy.[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008)[14](https://www.vitalsvault.com/peptides/mk-677#source-ncpa) ## MK-677 dosage There is no FDA-approved dose of MK-677 for any use. Most trials in people gave a single oral dose once a day for weeks to two years, with smaller and larger daily doses tested in short studies. The hip fracture trial at the usual trial dose was stopped early for heart failure. Your clinician sets your dose, if any.[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008)[10](https://www.vitalsvault.com/peptides/mk-677#source-sevigny-2008)[12](https://www.vitalsvault.com/peptides/mk-677#source-adunsky-2011)[6](https://www.vitalsvault.com/peptides/mk-677#source-chapman-1997) ## Typical MK-677 dosage Most trials in people gave MK-677 as an oral dose once a day, most often the same daily amount, for periods from four days to two years, in older adults, people with obesity and people with Alzheimer’s disease. A few short studies tested lower and higher daily doses. There is no approved dose, and a clinician sets any actual dose. These are reference doses from FDA labels, studies in people and clinical practice reports, shown for education. They are not a recommendation or a prescription. Your dose, form and schedule should be set by a licensed clinician who knows your history and lab results. Already have a prescribed dose? The [peptide dosage calculator](https://www.vitalsvault.com/peptides/tools/dosage-calculator) turns it into the units to draw on an insulin syringe. - Human trial · By mouth 25 mg Once daily[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008) 65 healthy adults aged 60 to 81, for up to two years - Human trial · By mouth 25 mg Once daily[10](https://www.vitalsvault.com/peptides/mk-677#source-sevigny-2008) 563 adults with mild to moderate Alzheimer’s disease, for 12 months - Human trial · By mouth 25 mg Once daily[12](https://www.vitalsvault.com/peptides/mk-677#source-adunsky-2011) Older adults recovering from hip fracture, planned for 24 weeks; stopped early for a heart failure safety signal - Human trial · By mouth 25 mg Once daily[9](https://www.vitalsvault.com/peptides/mk-677#source-svensson-1998) 24 men with obesity aged 18 to 50, for 8 weeks - Human trial · By mouth Young adults: 5 mg or 25 mg. Older adults: 2 mg, then 25 mg Once daily at bedtime[7](https://www.vitalsvault.com/peptides/mk-677#source-copinschi-1997) 8 healthy adults aged 18 to 30 (7 days per dose, crossover with placebo) and 6 healthy adults aged 65 to 71 (14 days per dose) - Human trial · By mouth 10 mg or 50 mg Once daily[6](https://www.vitalsvault.com/peptides/mk-677#source-chapman-1997) Nine young men with growth hormone deficiency, 4 days per dose Typical MK-677 doses in people, by source | Source | Form | Amount | How often | Notes | | --- | --- | --- | --- | --- | | Human trial[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008) | By mouth | 25 mg | Once daily | 65 healthy adults aged 60 to 81, for up to two years | | Human trial[10](https://www.vitalsvault.com/peptides/mk-677#source-sevigny-2008) | By mouth | 25 mg | Once daily | 563 adults with mild to moderate Alzheimer’s disease, for 12 months | | Human trial[12](https://www.vitalsvault.com/peptides/mk-677#source-adunsky-2011) | By mouth | 25 mg | Once daily | Older adults recovering from hip fracture, planned for 24 weeks; stopped early for a heart failure safety signal | | Human trial[9](https://www.vitalsvault.com/peptides/mk-677#source-svensson-1998) | By mouth | 25 mg | Once daily | 24 men with obesity aged 18 to 50, for 8 weeks | | Human trial[7](https://www.vitalsvault.com/peptides/mk-677#source-copinschi-1997) | By mouth | Young adults: 5 mg or 25 mg. Older adults: 2 mg, then 25 mg | Once daily at bedtime | 8 healthy adults aged 18 to 30 (7 days per dose, crossover with placebo) and 6 healthy adults aged 65 to 71 (14 days per dose) | | Human trial[6](https://www.vitalsvault.com/peptides/mk-677#source-chapman-1997) | By mouth | 10 mg or 50 mg | Once daily | Nine young men with growth hormone deficiency, 4 days per dose | ## Is MK-677 right for you? A clinician makes the call. These are the questions they will ask first. ### It may suit - Adults who want a clinician to review their metabolic and heart risk before deciding anything about growth hormone - People who want to know how MK-677 compares with peptides such as ipamorelin and GHRP-2 - Anyone who wants glucose, insulin and cortisol measured before and after ### Talk to a clinician first if you are - Heart failure, heart disease or leg swelling (FDA cites congestive heart failure risk) - Diabetes, prediabetes or insulin resistance - A personal or family history of cancer (growth hormone and IGF-1 promote cell growth) - Pregnant or breastfeeding - Tested athletes (WADA prohibits growth hormone secretagogues) Vitals Vault peptide care starts with a blood panel and a licensed clinician, and ends with a retest. [Get early access to peptide care](https://www.vitalsvault.com/peptides-waitlist) ## MK-677 vs GHRP-2 MK-677 vs GHRP-2 | Attribute | MK-677 | GHRP-2 | | --- | --- | --- | | What it is | Small molecule, not a peptide | Six-amino-acid peptide | | Route in studies | Oral | Intravenous, infusion, nasal | | Human trial length | Up to two years | Mostly single-day experiments | | FDA safety concern | Congestive heart failure | Insulin requirement, pancreatitis reports | ## More growth hormone is not the same as better function The two-year trial showed what raising growth hormone alone does in older adults. Lean mass rose, but strength and function did not change. The same trial found higher fasting glucose and lower insulin sensitivity, and some people had ankle swelling. That is why the metabolic baseline matters before anything that moves this axis.[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008)[7](https://www.vitalsvault.com/peptides/mk-677#source-copinschi-1997) ### What else moves the same system 1. 01Resistance trainingStrength did not change on MK-677 alone in the trial, so training is the lever that targets it. 2. 02Protein and total intakeMK-677 raises appetite and body weight, so food intake can undo a body composition goal. 3. 03SleepIn a small study, MK-677 changed how long people spent in deep and REM sleep. 4. 04Glucose and insulinFasting glucose, fasting insulin and HbA1c show how much room your metabolism has. ## Labs to check with MK-677 A blood test before you start and a retest after shows what actually changed for you. It is how Vitals Vault approaches every treatment. 1. TestA baseline panel at Quest Diagnostics. 2. DecideA licensed clinician reviews your history and results. 3. RetestThe same markers again, side by side. [Start with 120+ lab tests · $99](https://www.vitalsvault.com/labs#plans) - [Fasting glucoseA simple metabolic marker to retest.](https://www.vitalsvault.com/biomarkers/glucose) - [Fasting insulinShows insulin resistance earlier than glucose alone.](https://www.vitalsvault.com/biomarkers/insulin) - [HbA1cYour average blood sugar over about three months.](https://www.vitalsvault.com/biomarkers/hemoglobin-a1c) - [CortisolCortisol rose modestly in the two-year MK-677 trial, so a clinician may want a baseline for context.](https://www.vitalsvault.com/biomarkers/cortisol-total) ## Is MK-677 FDA approved? No. MK-677 (ibutamoren) is not an FDA-approved drug. FDA’s compounding safety page lists ibutamoren mesylate for both 503A and 503B because of the potential for congestive heart failure in certain patients, and it is not among the six peptides covered by the October 2026 enforcement discretion.[13](https://www.vitalsvault.com/peptides/mk-677#source-fda-bulks)[14](https://www.vitalsvault.com/peptides/mk-677#source-ncpa) ### MK-677 timeline 1. 1995 Merck chemists describe MK-0677, a potent, orally active non-peptide that acts like GHRP-6, and select it for clinical studies.[5](https://www.vitalsvault.com/peptides/mk-677#source-patchett-1995) 2. 1996 A Merck team clones the pituitary and hypothalamic receptor that growth hormone secretagogues act on.[1](https://www.vitalsvault.com/peptides/mk-677#source-howard-1996) 3. 2008 A two-year randomized trial in 65 healthy older adults shows higher growth hormone, IGF-1 and fat-free mass without better strength or function.[11](https://www.vitalsvault.com/peptides/mk-677#source-nass-2008) 4. 2008 A 12-month trial in 563 people with Alzheimer’s disease raises IGF-1 by about 73 percent but does not slow the disease.[10](https://www.vitalsvault.com/peptides/mk-677#source-sevigny-2008) 5. 2011 A trial in 123 hip fracture patients is stopped early after a congestive heart failure signal.[12](https://www.vitalsvault.com/peptides/mk-677#source-adunsky-2011) 6. April 2026 FDA’s compounding safety page lists ibutamoren mesylate for 503A and 503B, citing congestive heart failure risk.[13](https://www.vitalsvault.com/peptides/mk-677#source-fda-bulks) 7. October 29, 2026 FDA grants enforcement discretion for six named peptides. MK-677 is not among them.[14](https://www.vitalsvault.com/peptides/mk-677#source-ncpa) ![An Indigenous man, 62, heavy, silver braids, turquoise bolo collar rests on a truck tailgate, listening](https://www.vitalsvault.com/_next/image?url=%2Fpublic-v3%2Fshoot%2Fpeptides%2Ffaq-mk677.webp&w=3840&q=75&dpl=shadow-production-f0162cb4d465-40992538108-1) ## MK-677 questions Is MK-677 a peptide? No. MK-677 (ibutamoren) is a small-molecule drug taken by mouth. It mimics ghrelin and acts on the same receptor as peptides such as GHRP-2, GHRP-6 and hexarelin, which is why it is grouped with them. What is MK-677 used for? MK-677 has been studied for raising growth hormone and IGF-1, for lean mass in older adults and for recovery after hip fracture. People also ask about it for muscle and sleep. It is not FDA-approved for any use. What are the benefits of MK-677? In a two-year trial, it raised growth hormone and IGF-1 and increased fat-free mass by about a kilogram. It did not improve strength or function, and part of the weight gain was fat. What are the side effects of MK-677? Trials report more appetite, mild leg swelling, muscle pain, higher fasting glucose, lower insulin sensitivity and higher cortisol. A hip fracture trial stopped early for a congestive heart failure signal. Does MK-677 build muscle? In a two-year trial in healthy older adults, it raised fat-free mass by about a kilogram over a year while placebo lost half a kilogram. Strength and physical function did not improve, and part of the extra body weight was fat in the arms and legs. Does MK-677 help sleep? In one small sleep-lab study, a week of MK-677 increased the deepest stage of sleep by about half and REM sleep by over a fifth in young adults, and raised REM sleep in older adults. Larger and longer sleep studies have not been published in the sources here. MK-677 vs GHRP-2: what is the difference? Both act on the ghrelin receptor. MK-677 is a small molecule taken by mouth and has been tested in trials of up to two years. GHRP-2 is a six-amino-acid peptide given by injection or infusion, mostly in single-day experiments. FDA’s main concern for MK-677 is heart failure. What is the MK-677 dosage? There is no FDA-approved dose. Most trials in people used an oral dose once a day, for weeks up to two years, and the typical trial doses are listed in the dosage table on this page. In older adults after hip fracture that dose was linked to heart failure. Your clinician sets your dose. Does MK-677 raise blood sugar? In the two-year trial fasting glucose rose by about 5 mg/dL and insulin sensitivity fell. Anyone with diabetes or prediabetes should discuss that with a clinician and track glucose, insulin and HbA1c. Is MK-677 FDA approved? No. MK-677 is not an FDA-approved drug. FDA lists ibutamoren mesylate among bulk substances that may pose significant safety risks because of the potential for congestive heart failure. Is MK-677 banned in sports? Growth hormone secretagogues and releasing factors fall in the S2 class of the WADA Prohibited List, which applies in and out of competition. Tested athletes should not use MK-677. Can I get MK-677 through Vitals Vault? Vitals Vault is opening clinician-led peptide care that starts with a blood test. Join the peptides waitlist to hear first. A licensed clinician reviews your history and labs and decides what, if anything, is right for you. ## Peptides, prescribed and measured Vitals Vault is opening peptide care that starts with your blood work, is prescribed by licensed US clinicians and ends with a retest. Join the waitlist to hear first. - Prescription only - Licensed US clinicians - Quest Diagnostics labs [Get early access to peptide care](https://www.vitalsvault.com/peptides-waitlist)[Start with 120+ lab tests · $99](https://www.vitalsvault.com/labs#plans) ## Keep reading [Full Peptide Guide](https://www.vitalsvault.com/peptides) - IpamorelinA five-amino-acid growth hormone secretagogue that mimics ghrelin, studied for its selective release of growth hormone. - GHRP-2A six-amino-acid ghrelin-receptor agonist that triggers a sharp pulse of growth hormone. Used in Japanese diagnostic research. - GHRP-6An early synthetic ghrelin-receptor peptide, a six-amino-acid chain that triggers growth hormone release. - FDA peptide update 2026What FDA’s October 2026 decision on six peptides means for you. - CJC-1295A long-acting growth hormone releasing hormone analog, studied for raising growth hormone and IGF-1. ## Sources 1. 1. [Howard AD, et al. A receptor in pituitary and hypothalamus that functions in growth hormone release. Science. 1996 (opens in a new tab)](https://pubmed.ncbi.nlm.nih.gov/8688086/) 2. 2. [Kojima M, et al. Ghrelin is a growth-hormone-releasing acylated peptide from stomach. Nature. 1999 (opens in a new tab)](https://pubmed.ncbi.nlm.nih.gov/10604470/) 3. 3. [Ghigo E, et al. Growth hormone-releasing peptides. Eur J Endocrinol. 1997 (opens in a new tab)](https://pubmed.ncbi.nlm.nih.gov/9186261/) 4. 4. [Smith RG, et al. A nonpeptidyl growth hormone secretagogue. Science. 1993 (opens in a new tab)](https://pubmed.ncbi.nlm.nih.gov/8503009/) 5. 5. [Patchett AA, et al. Design and biological activities of L-163,191 (MK-0677): a potent, orally active growth hormone secretagogue. Proc Natl Acad Sci U S A. 1995 (opens in a new tab)](https://pubmed.ncbi.nlm.nih.gov/7624358/) 6. 6. [Chapman IM, et al. Oral administration of growth hormone (GH) releasing peptide-mimetic MK-677 stimulates the GH/insulin-like growth factor-I axis in selected GH-deficient adults. J Clin Endocrinol Metab. 1997 (opens in a new tab)](https://pubmed.ncbi.nlm.nih.gov/9329386/) 7. 7. [Copinschi G, et al. Prolonged oral treatment with MK-677, a novel growth hormone secretagogue, improves sleep quality in man. Neuroendocrinology. 1997 (opens in a new tab)](https://pubmed.ncbi.nlm.nih.gov/9349662/) 8. 8. [Murphy MG, et al. MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism. J Clin Endocrinol Metab. 1998 (opens in a new tab)](https://pubmed.ncbi.nlm.nih.gov/9467534/) 9. 9. [Svensson J, et al. Two-month treatment of obese subjects with the oral growth hormone (GH) secretagogue MK-677 increases GH secretion, fat-free mass, and energy expenditure. J Clin Endocrinol Metab. 1998 (opens in a new tab)](https://pubmed.ncbi.nlm.nih.gov/9467542/) 10. 10. [Sevigny JJ, et al. Growth hormone secretagogue MK-677: no clinical effect on AD progression in a randomized trial. Neurology. 2008 (opens in a new tab)](https://pubmed.ncbi.nlm.nih.gov/19015485/) 11. 11. [Nass R, et al. Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial. Ann Intern Med. 2008 (opens in a new tab)](https://pubmed.ncbi.nlm.nih.gov/18981485/) 12. 12. [Adunsky A, et al. MK-0677 (ibutamoren mesylate) for the treatment of patients recovering from hip fracture: a multicenter, randomized, placebo-controlled phase IIb study. Arch Gerontol Geriatr. 2011 (opens in a new tab)](https://pubmed.ncbi.nlm.nih.gov/21067829/) 13. 13. [FDA. Certain bulk drug substances for use in compounding that may present significant safety risks (current as of April 22, 2026) (opens in a new tab)](https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks) 14. 14. [NCPA. FDA grants enforcement discretion for compounding six peptides. October 29, 2026 (opens in a new tab)](https://ncpa.org/newsroom/qam/2026/10/29/fda-grants-enforcement-discretion-compounding-six-peptides) 15. 15. [World Anti-Doping Agency. Prohibited List (opens in a new tab)](https://www.wada-ama.org/en/prohibited-list) Written by the Vitals Vault editorial team, medically reviewed by Robert Lufkin, MD, and updated October 29, 2026. This is general education, not medical advice. None of these peptides is FDA-approved to diagnose, treat, cure or prevent any disease, and compounded medicines are not FDA-reviewed for safety, effectiveness or quality. Talk to a licensed clinician before starting any treatment. --- Canonical HTML: https://www.vitalsvault.com/peptides/mk-677 - [llms.txt](https://www.vitalsvault.com/llms.txt) - [sitemap.xml](https://www.vitalsvault.com/sitemap.xml) - [Developer portal](https://www.vitalsvault.com/developers)