The present invention relates to guanidine compounds of the general formula I corresponding enantiomeric, diastereomeric and/or tautomeric forms thereof as well as pharmaceutically acceptable salts thereof. The present compound further relates to the use of guanidine compounds as binding partners for 5-HT5 receptors for the treatment of diseases which are modulated by a 5-HT5 receptor activity, in particular for the treatment of neurodegenerative and neuropsychiatric disorders as well as the associated signs, symptoms and dysfunctions.