Analogs of growth hormone-releasing factor

A peptide of the formula:

• ##STR3## in which A.sub.1 is the D- or L- isomer of an amino acid selected from the group consisting of Tyr and His, or is deleted;
• A.sub.2 is Aib, or the D- or L- isomer of an amino acid selected from the group consisting of Ala, N-Me-Ala, and Arg;
• A.sub.8 is Ala, Aib, or Gly;
• A.sub.9 is Ala, Aib, or Gly;
• A.sub.10 is Phe or p-X-Phe where X is OH, CH.sub.3, or a halogen;
• A.sub.12 is Lys or N.sup..epsilon. -X-Lys where X is C.sub.1-6 alkyl, C.sub.1-6 acyl, C.sub.1-6 hydroxyalkyl, or C.sub.2-6 hydroxyacyl;
• A.sub.15 is Ala, Aib, or Gly;
• A.sub.16 is Ala, Aib, or Gly;
• A.sub.18 is Ala, Aib, or Gly;
• A.sub.21 is Lys or N.sup..epsilon. -X-Lys where X is C.sub.1 -C.sub.6 alkyl, C.sub.1 -C.sub.6 acyl, C.sub.1 -c.sub.6 hydroxyalkyl, or C.sub.2 -C.sub.6 hydroxyacyl;
• A.sub.22 is Ala, Aib, Gly, Leu, Ile, Val, Nle, Nva, or Abu;
• A.sub.24 is Ala, Aib, Gaba, Gly or His;
• A.sub.25 is Ala, Aib, Gaba, Gly, His or is deleted;
• A.sub.26 is Ala, Aib, Gaba, Gly, His or is deleted;
• A.sub.27 is Ala, Aib, Gly, Leu, Ile, Val, Nle, Nva, Abu, Gaba, .beta.-Ala, Ava, His, or is deleted;
• A.sub.28 is Aib, the D- or L- isomer of Ala, Gaba, His, or is deleted;
• each of R.sub.1 and R.sub.2 is, independently, H, C.sub.1-12 alkyl, C.sub.7-20 phenylalkyl, C.sub.11-20 napthylalkyl, C.sub.1-12 hydroxyalkyl, C.sub.7-20 hydroxyphenyl, C.sub.11-20 hydroxynapthylalkyl, or COE.sub.1 where E.sub.1 is C.sub.1-12 alkyl, C.sub.7-20 phenylalkyl, C.sub.11-20 napthylalkyl, C.sub.1-12 hydroxyalkyl, C.sub.7-20 hydroxyphenylalkyl, or C.sub.11-20 hydroxynapthylalkyl;
• and
• R.sub.3 is OH, NH.sub.2, C.sub.1-12 alkoxy, or NH.Y.CH.sub.2.Z where Y is a C.sub.1-12 hydrocarbon moiety and Z is H, OH, CO.sub.2 H, or CONH.sub.2 ;
• or a pharmaceutically acceptable salt thereof.