France lock Pascal Pape has failed to overturn a 10-week suspension for kneeing Ireland's Jamie Heaslip in the back last month.
The 34-year-old Stade Francais second row was shown a yellow card by referee Wayne Barnes in the 52nd minute of Ireland's 18-11 win in Dublin.
Heaslip was replaced in the second half after damaging three vertebrae.
An independent appeal committee ruled Pape's suspension would stand following a hearing on Tuesday.
Pape will miss the remainder of the Six Nations - games against Italy and England - and can only return to action on May 18.