Pharmacologically active peptides

Abstract

Compounds of the formula ##STR1## and pharmaceutically acceptable non-toxic acid addition salts thereof, in which L and D define the chirality; R.sub.1 is hydrogen or C.sub.1 -C.sub.3 primary alkyl; R.sub.2 is C.sub.1 -C.sub.4 primary or secondary alkyl, allyl, cyclopropylmethyl, C.sub.1 -C.sub.2 hydroxyalkyl, or --(CH.sub.2).sub.m --U--CH.sub.3 in which U is --S-- or >S--O and m is 1 or 2; R.sub.3 is hydrogen, C.sub.1 -C.sub.4 primary or secondary alkyl, cyclopropylmethyl, or allyl; R.sub.4 is hydrogen, C.sub.1 -C.sub.5 primary or secondary alkyl, --(CH.sub.2).sub.n --X--(CH.sub.2).sub.p --CH.sub.3 in which X is --O--, --S--, >S--O or ##STR2## n is 1 or 2, and p is 0 or 1, phenyl, or monosubstituted phenyl in which the substituent is halo, hydroxy, C.sub.1 -C.sub.3 alkoxy, nitro, C.sub.1 -C.sub.3 alkyl, or trifluoromethyl; R.sub.5 is hydrogen or C.sub.1 -C.sub.4 primary alkyl; and Z is --CH.sub.2 OR.sub.6, ##STR3## in which R.sub.6 is hydrogen or C.sub.1 -C.sub.3 alkyl and R.sub.7 is C.sub.1 -C.sub.3 alkyl; subject to the proviso that one but not both of R.sub.3 and R.sub.5 is other than hydrogen; are useful analgesic agents.

Dependencies are inferred from the claim text.