The present invention relates to the therapeutic use of a phenyl-butyric acid, a derivative or a physiologically acceptable salt thereof, like 4-phenylbutyric acid (4-PB) or its sodium salt, in the treatment of various diseases. Particularly, the present invention provides phenyl-butyric acid, a derivative or a physiologically acceptable salt thereof, like 4-phenylbutyric acid (4-PB) or its sodium salt at low daily dosis for use in the treatment of various diseases, pharmaceutical compositions and kits comprising 4-PB at low dosis for the treatment of various diseases, and methods for treatment of various diseases involving the administration of phenyl-butyric acid, a derivative or a physiologically acceptable salt thereof, like 4-phenylbutyric acid (4-PB) or its sodium salt, at low daily dosis.
