Phenanthrene derivatives of formula I for use as medicaments. The present invention refers to phenanthrene derivatives for use as medicaments, mainly in the prevention and/or treatment of DM1, HDL2, SCA8, DM2, SCA3, FXTAS, FTD/ALS, and SCA31. In a preferred embodiment, phenanthrene derivatives of the invention are also used as antimyotonic agents.