Flupirtine acid addition salts having the following formula (2), ##STR00001## wherein R represents a substituted or unsubstituted C.sub.1-C.sub.12-alkyl or a substituted or unsubstituted C.sub.6-C.sub.10-aryl group, have been prepared.
The preparation of flupirtine carboxylate acid addition salts having the following formula (2), ##STR00001## wherein R represents hydrogen or a C.sub.1-C.sub.6 alkyl group, with the proviso that RCOOH is neither maleic acid nor gluconic acid, is described.
