What is Swiss Chems MK677 Ibutamoren? MK-677, also known as ibutamoren or ibutamoren mesylate, is often a peptide that belongs to The expansion hormone secretagogues team (GHSR). It works by mimicking the action of the starvation hormone ghrelin. It binds to 1 of The expansion hormone secretagogue receptors (GHSR) while in the brain, serving to enh