precisely what is Swiss Chems MK677 Ibutamoren? MK-677, often called ibutamoren or ibutamoren mesylate, is usually a peptide that belongs to the growth hormone secretagogues team (GHSR). It works by mimicking the action in the starvation hormone ghrelin. It binds to at least one of the growth hormone secretagogue receptors (GHSR) from the brain, en