Naphthalene amides and sulphonamides, processes for their preparation and pharmaceutical compositions containing them

A compound selected from those of the formula (I):

• ##STR61## it being possible for each of the two substituents, independently of the other, to be located on either one of the two naphthalene rings, and wherein
• R.sub.1 and R.sub.2, which are the same different, each represents, independently of the other, a radical selected from:
• hydrogen,
• straight-chain or branched alkyl having 1 to 6 carbon atoms, inclusive,
• cycloalkyl, having 3 to 7 carbon atoms, inclusive, or cycloalkyl(C1-C4)alkyl,
• straight-chain or branched alkyl having 2 to 6 carbon atoms inclusive,
• optionally substituted aryl,
• and optionally substituted aralkyl of which the alkyl chain has 1 to 3 carbon atoms, inclusive,
• R.sub.3 represents:
• ##STR62## wherein R.sub.6 and R.sub.7, which are the same or different, have the same definition as R.sub.1 and R.sub.2,
• an optical isomer therefore,
• and an addition salt with a pharmaceutically-acceptable mineral or organic acid;
• "aryl" meaning a group selected from phenyl, naphthyl;
• the expression "optionally substituted meaning that the aromatic nucleus or nuclei may be substituted by one or more radicals selected from hydroxy, halogen, trifluoromethyl, nitro, straight-chain or branched alkyl having 1 to 6 carbon atoms, inclusive, and straight-chain or branched alkoxy having 1 to 6 carbon atoms, inclusive.