A compound of formula (I): ##STR1## in which: R.sub.1 represents substituted or unsubstituted phenyl or (C.sub.3 -C.sub.7) cycloalkyl,R.sub.2 represents trifluoromethyl or (C.sub.3 -C.sub.4) cycloalkyl,A represents --CH.sub.2 --, --CH.dbd.N--, .dbd.N-- or --NH--,R.sub.3 and R.sub.4, which may be identical or different, represent hydrogen or linear or branched (C.sub.1 -C.sub.6) alkyl or, with the nitrogen atoms to which they are attached, form a 5- or 6-membered heterocycle,R represents either hydrogen in the case where A=--CH.sub.2 --, --CH.dbd.N-- or --NH--, or a bond of the group A when the latter is equal to .dbd.N--,its enantiomers and epimers as well as its addition salts with a pharmaceutically acceptable acid.Medicine products.