The condensation of gamma-aminobutylic acid (I) with 3,4-methylenedioxyphenylisothiocyanate (II) in ethanol-H2O gives 1-[3-(carboxy)propyl]-3-(3,4-methylenedioxyphenyl)thiourea (III), which is allowed to react with 3-[3-(piperidinomethyl)phenoxy]propylamine (IV) by means of ethyl chloroformate and triethylamine in dichloromethane to afford TRM-115.