Kangaroos and NSW Origin forward Trent Merrin says prescription drug abuse in the NRL is an "uncontrollable", but the onus remains squarely on the individual.

Merrin, who is part of the Penrith side that will face the Warriors in Christchurch on Saturday, was speaking in the wake of the recent Warriors' scandal, which saw five players stood down for taking a mix of prescription drugs and energy drinks.

Ben Matulino and Bodene Thompson return to NRL action tomorrow, but Sam Lisone and Albert Vete will play NSW Cup. Manu Vatuvei remains on medical leave. Konrad Hurrell was also disciplined for being part of the night out, though he denies taking the cocktail of substances.

"It can happen in any sport," said Merrin. "It's a bit of an issue but you can't really control it - it's one of those uncontrollables in the game."


Merrin, who is in his eighth season of first grade and has played 11 times for NSW, says clubs and the game's governing body can only do so much.

"You can deliver a message about what can come from these kind of things but at the end of the day it falls back on the individual and what they want to do," said Merrin.

"The message is out there to stay away from it but it falls back on the individual and the consequences are their own."

Penrith teammate Peta Hiku, who came through the grades at the Warriors before leaving for Manly at the end of the 2011 season, admits he was disappointed by the recent events at the Mt Smart club.

"Every coach is different," said Hiku, "And they have their way of sorting out whatever happened. I am friends with most of those guys and I was disappointed to see them not playing grade. But I was really happy that a few of them get to come back and play this weekend."

Hiku is expecting a big response from Matulino and Thompson on Saturday, after being stood down from club and representative football over the past two weeks.

"They'll be real fired up," said Hiku. "They have been out for a while and they missed a chance to play for their country."

The Warriors arrive in Christchurch this afternoon, before a brief captains run at AMI stadium this evening.