[[2-(amino-3,4-dioxo-1-cyclobuten-1-yl) amino]alkyl]-acid derivatives

A method for preventing convulsions and neurodegenerative disorders induced by overstimulation of excitatory amino acid receptors, which comprises administering to a mammal suffering from such convulsions or neurodegenerative disorders, an anticonvulsant, neuroprotective amount of an NMDA antagonist of the formula:

• ##STR13## in which R.sup.1 and R.sup.2 taken together are --CH.sub.2 CH.sub.2 --, --CH.sub.2 C(R.sup.6)(R.sup.7)CH.sub.2 -- or --CH.sub.2 C(R.sup.8)(R.sup.9)--C(R.sup.10)(R.sup.11)CH.sub.2 --, where R.sup.6, R.sup.8 and R.sup.10 are, independently, hydrogen, alkyl of 1 to 6 carbon atoms or hydroxyl and R.sup.7, R.sup.9 and R.sup.11 are, independently, hydrogen or alkyl or 1 to 6 carbon atoms;
• A is alkylene of 1 to 6 carbon atoms or alkenylene of 2 to 6 carbon atoms;
• X is CO.sub.2 R.sup.3 in which R.sup.3 is hydrogen or alkyl of 1 to 6 carbon atoms, P(O)(OR.sup.4)(OR.sup.5) in which R.sup.4 and R.sup.5 are, independently, hydrogen or alkyl of 1 to 6 carbon atoms, 3,5-dioxo-1,2,4-oxadiazolidin-2-yl or 5-tetrazolyl;
• or a pharmaceutically acceptable salt thereof.

A method for preventing brain cell damage resulting from overstimulation by excessive amounts of excitatory amino acids which comprises administering to a mammal suffering from neurodegeneration an effective amount of an NMDA antagonist of the formula:

• ##STR14## in which R.sup.1 and R.sup.2 taken together are --CH.sub.2 CH.sub.2 --, --CH.sub.2 C(R.sup.6)(R.sup.7)CH.sub.2 -- or --CH.sub.2 C(R.sup.8)(R.sup.9)--C(R.sup.10)(R.sup.11)CH.sub.2 --, where R.sup.6, R.sup.8 and R.sup.10 are, independently, hydrogen, alkyl of 1 to 6 carbon atoms or hydroxyl and R.sup.7, R.sup.9 and R.sup.11 are, independently, hydrogen or alkyl of 1 to 6 carbon atoms;
• A is alkylene of 1 to 6 carbon atoms or alkenylene of 2 to 6 carbon atoms;
• X is CO.sub.2 R.sup.3 in which R.sup.3 is hydrogen or alkyl of 1 to 6 carbon atoms, P(O)(OR.sup.4)(OR.sup.5) in which R.sup.4 and R.sup.5 are, independently, hydrogen or alkyl of 1 to 6 carbon atoms, 3,5-dioxo-1,2,4-oxadiazolidin-2-yl or 5-tetrazolyl;
• or a pharmaceutically acceptable salt thereof.