Jonathan Sexton (2), Andrew Trimble, Cian Healy, Sean Cronin, Fergus McFadden and Jack McGrath were all among the scorers for Joe Schmidt's side - adding to their already dominant points difference.
Italy remain winless but were level at 7-7 against Ireland after a well-taken try from Leonardo Sarto.
After the break however, Ireland turned the screw and Brunel admits the Azzurri were overcome by the in-form Irish.
"We suffered a bit too much pressure from the Irish," said the Italy coach. "Halfway through the game I thought we'd be able to stay on that level, but at the beginning of the second half we had the problem of continuity.
"They had the ability to find the turnover on the area of the tackle, they are a great team.
"Nevertheless, we did 50-55 minutes of quality in relation to the changes made in our team. It was not enough."