What is Swiss Chems MK677 Ibutamoren? MK-677, often called ibutamoren or ibutamoren mesylate, is a peptide that belongs to The expansion hormone secretagogues team (GHSR). it really works by mimicking the action of your starvation hormone ghrelin. It binds to at least one of The expansion hormone secretagogue receptors (GHSR) inside the brain, supp