(4-Threonine)oxytocin 1,2-Dithia-5,8,11,14,17-penaazacycloeicosane, cyclic peptide deriv. 26995-91-5 27115-19-1 4-(L-Threonine)oxytocin Oxytocin, 4-L-threonine- Urofollitropin