Benzo[1,8]naphthyridine derivatives, their preparation and pharmaceutical compositions which comprise them

A benzo[b][1,8]naphthyridine compound of the formula (I):

• in which:
• R1 and R2, which are identical or different, represent:
• an alkyl or cycloalkyl radical having 3 to 8 members,
• or R1 and R2 form, together with the nitrogen atom to which they are attached, a 6-membered heterocycle optionally having one more nitrogen atom, which, when present, is substituted at the 4-position by:
• a phenyl radical,
• a phenyl radical substituted by a halogen atom or by an alkylthiomethyl radical,
• a benzyl radical,
• a benzyl radical substituted by a halogen atom,
• a heterocyclylmethyl radical, the heterocyclyl part of which is saturated or unsaturated and has 5 or 6 members,
• a phenylamino radical, the phenyl part of which is optionally substituted by a halogen atom,
• or R1 and R2 form, together with the nitrogen atom to which they are attached, a 7-membered heterocycle, optionally having one more nitrogen atom, which, when present, is substituted by one of the above-listed substituents of the 6-membered heterocycle;
• or R1 and R2 form, together with the nitrogen atom to which they are attached, an 8-membered heterocycle, optionally having one more nitrogen atom, which may be optionally substituted by one of the above-listed substituents of the 6-membered heterocycle;
• R3 represents:
• an alkyl radical,
• a fluoroalkyl radical,
• a carboxyalkyl radical,
• a cycloalkyl radical having 3 to 6 carbon atoms,
• a fluorophenyl radical,
• a difluorophenyl radical,
• an alkyloxy radical, or
• an alkylamino radical;
• and
• R4 represents a hydrogen atom or a fluorine atom,
• wherein the abovementioned alkyl radicals are straight or branched and has 1 to 4 carbon atoms;
• or a stereoisomeric form thereof, a mixture of stereoisomeric forms thereof, a metal salt, an addition salt with a nitrogenous base, or an acid addition salt thereof.