Description
MK-677 is a non-steroidal selective androgen receptor modulator (SARM) that selectively binds to androgen receptors in the body, inducing anabolic effects . It has been shown to increase muscle mass and strength in castrated male rats . In a 2016 study published in the Journal of Steroid Biochemistry and Molecular Biology, it was found that AC-262 increased bone density and reduced fat mass in female rats.
Specifications
- Chemical Formula: C27H36N4O5S
- Molecular Mass: 528.67 g/mol
- Synonyms: Ibutamoren
- CAS Number: 159634-47-6
- PubChem: 178024
- Total Amount of the Active Ingredient: 12.5mg/caps and 60 capsules
- Shelf Life: 36 months
Minimize open air exposure, store in a cool dry place
Research Studies
Abstract
Obesity is associated with blunted GH secretion, unfavorable body composition, and increased cardiovascular mortality. The objective of this study was to investigate the effects of oral treatment with the GH secretagogue MK-677 on GH secretion and body composition in otherwise healthy obese males. The study was randomized, double blind, parallel, and placebo controlled. Twenty-four obese males, aged 18–50 yr, with body mass indexes greater than 30 kg/m2 and waist/hip ratios greater than 0.95, were treated with MK-677 25 mg (n = 12) or placebo (n = 12) daily for 8 weeks.
Serum insulin-like growth factor I (IGF-I) increased approximately 40% with MK-677 treatment (P < 0.001 vs. placebo). Serum IGF-binding protein-3 was also significantly increased (P ≤ 0.001 vs. placebo). GH and PRL (peak and area under the curve values) were significantly increased after the initial dose of MK-677. Significant increases, with the exception of peak PRL, persisted at 2 and 8 weeks of treatment. The increases in GH and PRL after the initial dose were significantly greater than the increase seen after multiple doses. Serum and urinary concentrations of cortisol were not increased at 2 and 8 weeks (P = NS, vs. placebo). Fat-free mass increased significantly in the MK-677 treatment group when determined with dual energy x-ray absorptiometry (P < 0.01) or using a four-compartment model (P < 0.05). Total and visceral fat were not significantly changed with active therapy. The basal metabolic rate was significantly increased at 2 weeks of MK-677 treatment (P = 0.01) but not at 8 weeks (P = 0.1). Fasting concentrations of glucose and insulin were unchanged, whereas an oral glucose tolerance test showed impairment of glucose homeostasis at 2 and 8 weeks.
We conclude that 2-month treatment with MK-677 in healthy obese males caused a sustained increase in serum levels of GH, IGF-I, and IGF-binding protein-3. The effects on cortisol secretion were transient. Changes in body composition and energy expenditure were of an anabolic nature, with a sustained increase in fat-free mass and a transient increase in basal metabolic rate. Further studies are needed to evaluate whether a higher dose of MK-677 or a more prolonged treatment period can promote a reduction in body fat.
MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism
Abstract
The reversal of diet-induced negative nitrogen balance by GH suggests a possible therapeutic role for GH treatment in catabolic patients. A double-blind, randomized, placebo-controlled, two-period, cross-over study was designed to investigate whether MK-677, an orally active nonpeptide mimic of GH-releasing peptide, can reverse diet-induced protein catabolism. Eight healthy volunteers (ages 24–39 yr) were calorically restricted (18 kcal/kg·day) for two 14-day periods. During the last 7 days of each diet period, subjects received either oral MK-677 25 mg or placebo once daily. There was a 14- to 21-day washout interval between periods. During the first week of caloric restriction (i.e. diet alone), daily nitrogen losses were similar for both treatment groups (mean ± SE; MK-677 group −2.67 ± 0.40 g/day vs. placebo group− 2.83 ± 0.26 g/day). During the second week (diet and study drug), mean daily nitrogen balance was 0.31 ± 0.21 g/day in the MK-677 treatment group compared with −1.48 ± 0.21 g/day in the placebo group (P < 0.01). MK-677 improved nitrogen balance integrated over the 7 days of treatment; area under the curve day 8–14 nitrogen balance response was +2.69 ± 5.0 (SE) for MK-677 and −8.97 ± 5.26 g·day for placebo (P < 0.001). MK-677 produced a peak GH response of 55.9 ± 31.7 μg/L after single dose (day 1 of treatment) and 22.6 ± 9.3 μg/L after a week of dosing compared with placebo treatment peak GH values of approximately 9 (treatment day 1) and approximately 7 μg/L (treatment day 7). Following the initial 7-day caloric restriction, insulin-like growth factor-I (IGF-I) declined from 232 ± 25 to 186 ± 19 ng/mL in the MK-677 group and from 236 ± 19 to 174 ± 23 ng/mL in the placebo group. Mean IGF-I concentration increased significantly during MK-677 to 264 ± 31 ng/mL (mean for the last 5 days of treatment) compared with 188 ± 19 ng/mL with placebo (P < 0.01). No significant difference in IGF binding protein-2 was found between the MK-677 and placebo treatments. However, the mean in IGF binding protein-3 for the last 5 days of MK-677 treatment was also significantly increased to 3273 ± 330 ng/mL (mean ± SE) compared with placebo 2604 ± 253 ng/mL (P < 0.01). Neither the serum cortisol nor the PRL response was significantly greater after 7 days of MK-677 dosing compared with 7 days of placebo. MK-677 (25 mg) was generally well tolerated and without clinically significant adverse experiences. In conclusion, MK-677 reverses diet-induced nitrogen wasting, suggesting that if these short-term anabolic effects are maintained in patients who are catabolic because of certain acute or chronic disease states, it may be useful in treating catabolic conditions.
Effect of the Orally Active Growth Hormone Secretagogue MK-677 on Somatic Growth in Rats
Abstract
Purpose: Growth hormone secretagogues (GHSs) possess the ability to release growth hormone (GH) in the body. This study aimed to investigate the effects of MK-677, an orally active GHS, on somatic growth in rats.
Materials and methods: The serum levels of GH were measured after oral administration of MK-677 to confirm GH stimulatory effects. Body weight, body length, tibia length, epiphyseal plate width, and serum levels of insulin-like growth factor (IGF)-I were measured after oral administration of 4 mg/kg of MK-677 for 6 weeks to investigate growth-promoting effects.
Results: Oral administration of MK-677 at 4 mg/kg increased peak GH concentrations by 1.8-fold, compared to baseline. However, oral administration of MK-677 for 6 weeks did not increase body growth or serum levels of IGF-I. At 6 weeks after treatment, the GH response to MK-677 was abolished. Pituitary GH mRNA and hypothalamic GH-releasing hormone mRNA, and GH secretagogue receptor (GHSR) mRNA expression in the pituitary and hypothalamus did not differ between the control and treatment group. Somatostatin (SST) mRNA expression in the hypothalamus was markedly increased in the treatment group, whereas SST receptor (SSTR)-2 mRNA expression in the pituitary gland was decreased. Protein expression of hypothalamic GHSR, SST, and pituitary SSTR-2 showed patterns similar to those for mRNA expression.
Conclusion: Our results suggest that prolonged administration of MK-677 in rats does not promote growth despite the GH stimulatory effect of MK-677, which may be related to increased expression of SST in the hypothalamus. Further studies are needed to overcome the observed desensitization to GHS.
Disclaimer
The information provided above is not intended to substitute medical advice, diagnosis, or treatment. Should you have any questions regarding a medical condition, seek the advice of your physician or a qualified healthcare provider. In no case should medical advice be disregarded or delayed because of what you have read or seen. We bear no responsibility or liability for your use of any of our research compounds and products. Please note that they are being sold for research purposes ONLY. We do NOT condone any personal use.
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ALL ARTICLES AND PRODUCT INFORMATION PROVIDED ON THIS WEBSITE ARE FOR INFORMATIONAL AND EDUCATIONAL PURPOSES ONLY.
The products offered on this website are intended for in-vitro studies only. In-vitro studies (Latin: “in glass”) are performed outside the body. These products are not medicines or drugs and have not been approved by the FDA to prevent, treat, or cure any medical condition, ailment, or disease. Bodily introduction of any kind into humans or animals is strictly forbidden by law.
