N-alkylglycine trimeres, their stereoisomers, racemic mixtures and salts of formula (I) below, where R1, R2 and R3, independent of one another, are chosen from amongst cyclopropyl, sec-butyl, 2-methoxyethyl, 3-methylbutyl, cyclohexyl, 2-(N-pyrrolidinyl)ethyl, 2-(methylcarbonylamine)ethyl, 3-(2-oxo-N-pyrrolidinyl)propyl, 2-(2-pyridyl)ethyl, 2-phenylethyl, 1-(2-tetrahydrofuryl)methyl, 2-(N-imidazolyl) ethyl, 2-(4-methoxyphenyl)ethyl, 2-(3,4-dimethoxyphenyl)ethyl, 2-(2,4-dichlorophenyl)ethyl, 2-[2-(N-methyl)pyrrolidinyl]ethyl, 2-(4-aminosulfonylphenyl)ethyl, 2-(morpholine)ethyl, 3-(N,N-diethylamine)propyl, 3,3-diphenyipropyl, 3-(N,N-dimethylamine)propyl, and 2-(N,N-diethylamine)ethyl, their stereoisomeric forms and their mixtures, which are capable of blocking L-glutamate receptors and are useful for treating disorders mediated by neurodegeneration, for example, cerebral ischemia, cerebrovascular accident, migraine, depression, Huntington, Parkinson, Alzheimer, senile dementia, epilepsy and multiple and amyotrophic sclerosis.