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