3-Pyrrolin-2-one derivatives and compositions

A compound of the formula:

• ##STR4## wherein R.sub.1 and R.sub.2 together with the nitrogen atom to which they are attached form a saturated 5-, 6- or 7-membered heterocyclic ring which can also contain a further nitrogen atom or an oxygen or sulphur atom, A is a straight-chain or branched hydrocarbon chain containing 2 to 4 carbon atoms and R.sub.3 is a saturated or unsaturated, straight-chain or branched aliphatic hydrocarbon radical containing up to 6 carbon atoms or is the radical --Alk--Ar, wherein Alk is an alkylene chain containing up to 3 carbon atoms and Ar is a phenyl or heteroaryl radical optionally substituted by halogen atoms and/or lower alkoxy radicals;
• and the pharmacologically compatible salts thereof.