  We provide an analytical proof of the entropic uncertainty relations
presented by de Vicente and Sanchez-Ruiz in [Phys. Rev. A 77, 042110 (2008)]
and also show that the replacement of Eq. (27) by Eq. (29) in that reference
introduces solutions that do not take fully into account the contraints of the
problem, which in turn leads to some mistakes in their treatment.
