What is Swiss Chems MK677 Ibutamoren? MK-677, also called ibutamoren or ibutamoren mesylate, is usually a peptide that belongs to the growth hormone secretagogues group (GHSR). it really works by mimicking the motion of the starvation hormone ghrelin. It binds to at least one of The expansion hormone secretagogue receptors (GHSR) during the brain,