The 28-year-old flanker suffered a recurrence of a shoulder injury playing for Leinster in the European Cup and was withdrawn from the squad when they met up for a five-day camp in Dublin.
His place in the 34-man squad has been taken by uncapped Roger Wilson, the 23-year-old flanker who has caught the eye with a string of impressive performances for Ulster this season.
Coach Eddie O'Sullivan, who will name his team next week, has still not ruled out new captain Brian O'Driscoll, who is struggling to overcome a slight calf tear.
Meanwhile, O'Driscoll is continuing talks with the IRFU over a new contract, with the Lions centre insisting he has not ruled out a move to either England or France.
O'Driscoll, recently installed as successor to Keith Wood, has just four months left on his current deal and has been involved in negotiations for the last two months.
"I'm keeping my options open on what I'm going to do and where I'm going to go." he told the BBC. "My contract is up in June and there will be plenty of talking between now and then," he said. "I feel it's a bit of an exciting time for me.
"I may be a real Dubliner, but I'm a bit of a hometown boy who is not afraid to experience new things."
IRFU spokesman John Redmond said: "Talks are ongoing, as they are with all the contracted players, and the hope of the IRFU is to keep everybody at home, as has always been their objective."