Use of diamino ketones as analgesic agents

A method of relieving pain in a mammalian host suffering therefrom, which comprises administering an effective amount of a compound having the formula ##STR15## or a pharmaceutically acceptable salt thereof, wherein R.sub.1 and R.sub.2 are each independently hydrogen, alkyl, carboxyalkyl, halo substituted alkyl, hydroxyalkyl, aminoalkyl, mercaptoalkyl, alkylthioalkyl, (cycloalkyl)alkyl, (heteroaryl)alkyl, arylalkyl, carbamoylalkyl, guanidinylalkyl, or heteroaryl;

• R.sub.3 is hydroxy, alkoxy, (substituted alkyl)oxy, arylalkoxy, (heteroaryl)alkoxy or --NY.sub.1 Y.sub.2, wherein Y.sub.1 and Y.sub.2 are each independently hydrogen, alkyl, aryl, or arylalkyl, or Y.sub.1 is hydrogen and Y.sub.2 is substituted alkyl or (heteroaryl)alkyl;
• A.sub.1 is glycyl, alanyl, leucyl, phenylalanyl, arginyl, sarcosyl, seryl, asparagyl, lysyl, glutamyl, histidyl, tryptophyl, cysteinyl, methionyl, threonyl, tyrosyl, leucyl, valyl, aspartyl, prolyl, norleucyl, norvalyl, or ##STR16## wherein n.sub.6 is an integer of 2 to 15;
• A.sub.2, A.sub.3, A.sub.4 and A.sub.5 each is independently glycyl, alanyl, leucyl, phenylalanyl, arginyl, sarcosyl, seryl, asparagyl, lysyl, glutamyl, histidyl, tryptophyl, cysteinyl, methionyl, threonyl, tyrosyl, leucyl, valyl, aspartyl, prolyl, norleucyl, or norvalyl;
• and
• n.sub.1, n.sub.2, n.sub.3, n.sub.4 and n.sub.5 each is independently 0 or 1;
• and wherein
• the terms "alkyl" and "alkoxy" refer to straight and branched chain groups having 1 to 7 carbon atoms;
• the term "halo substituted alkyl" refer to alkyl groups in which one, or more, hydrogens have been replaced by chloro, bromo, or fluoro groups;
• the term "cycloalkyl" refers to cycloalkyl groups having 3, 4, 5, 6, or 7 carbon atoms;
• the term "substituted alkyl" refers to alkyl groups substituted with one, or more, hydroxy or --NY.sub.3 Y.sub.4 groups wherein Y.sub.3 and Y.sub.4 are the same or different and each is hydrogen or alkyl, Y.sub.3 is hydrogen and Y.sub.4 is aryl, or Y.sub.3 and Y.sub.4 together with the nitrogen atom to which they are attached form a heterocyclic group having the formula ##STR17## and A is CH--Q, oxygen, or N--Q, Q is hydrogen or alkyl and m is 0 or 1;
• the term "heteroaryl" refers to 2- or 3-furanyl, 2- or 3-thienyl, 2-, 3- or 4-pyridinyl, 4-imidazolyl and 3-indolyl;
• and
• the term "aryl" refers to phenyl and phenyl substituted with 1, 2 or 3 alkyl, alkoxy, alkylthio, hydroxy, chlorine, bromine, fluorine, amino, alkylamino, dialkylamino, nitro or trifluoromethyl groups.