Abstract: Analogues of 8-D-homoarginine vasopressin were prepared with the general formula ##STR1## where X is L-O-methyltyrosine, L-p-ethylphenylalanine, D-p-ethylphenylalanine, L-p-methylphenylalanine or D-methylphenylalanine and R is cysteine or .beta.-mercaptopropionic acid. These vasopressin analogues exhibited an increased affinity to uterus receptors for oxytocin, where they acted as ocytocin antagonists. Moreover, the analogues of deamino vasopressin have a significantly reduced antidiuretic activity in comparison with [8-D-arginine]vasopressin.

Abstract: Vasopressin analogs of the formula ##STR1## wherein R.sup.1 is H, R.sup.2 is CH.sub.2 S and R.sup.3 is D-Arg,R.sup.1 is NH.sub.2, R.sup.2 is S-S and R.sup.3 is D-Arg or L-Orn are described. The described analogs resist enzymatic cleavage while retaining their effect on the central nervous system. These compounds lack a glycinamide residue in the 9 position and have the L-arginine in the 8 position replaced with its stereoisomeric form or with an ornithine residue. The compounds evidence little or no peripheral endocrine effects of natural vasopressin.