Carter explained that he had a corticosteroid injection after Racing's Top 14 semi-final victory over Clermont
All Blacks great Dan Carter insists he has never come across banned substances in rugby, after himself being cleared in a doping probe.
Carter, fellow former All Black Joe Rokococo and Argentinian winger Juan Imhoff, who all play for Racing 92, were the target of an investigation by the medical commission of the French Rugby Federation after testing positive for corticosteroids following last season's Top 14 final.
But the trio, as well as Racing's medical staff, were all cleared of any wrongdoing.
Speaking to franceinfo in an interview, Carter said he had never encountered doping in rugby.
"No, never, right throughout my career," said the fly-half, capped 112 times by New Zealand and a two-time World Cup winner.
"I have huge confidence in the authorities that keep this game clean.
"I hold my integrity and the game's integrity at the highest level and I have full trust that the authorities are making sure that this game is kept clean under the anti-doping regulations -- and they've put a lot of procedures in place to make sure that it is.
"I have full confidence our game is played in a clean way and am confident it will continue to be that way for a long time."
Carter explained that he had a corticosteroid injection after Racing's Top 14 semi-final victory over Clermont, when he picked up a swollen knee.
"The following two days complete rest and then I was able to play following that," he said, with him and Rokocoko going on to notch up 20 points between them in Racing's final win over Toulon.
"I have full trust in the medical team and am extremely confident that we stayed within the anti-doping regulations which has been proven we did."
When asked whether he thought others abused the use of corticosteroids, Carter said: "I can't really speak for other people, other athletes, other rugby players.
"For me I had an injury. When you have an injury you want to cure the injury within the anti-doping regulations and that's exactly what I did."
Carter, who made his debut for the All Blacks in 2003 admitted, however, the temptation might be there given the seismic changes the ever-increasing rate of professionalism brings although he argued that was countered by the staggering advances in the better nurturing of players.
"The game has definitely changed, it's a lot more demanding," said the world record Test points scorer (1,598).
"The players are stronger, the game is faster.
"But there's all the science and understanding behind the game is just so much more advanced than it was 10 years ago.
"There are things in terms of our recovery that I wasn't doing at the start of my career, things like cryotherapy, stretching, massage twice a week, hot and cold baths."
Carter also dismissed talk that players turned out in too many games in France compared to his native New Zealand.
"It's very similar," the playmaker said. "There's a long demanding season here. It probably wasn't helped it was a World Cup year and the season was extended a little bit further.
"But I'm very lucky to play for a quality side like Racing where we have a lot of depth. I was managed throughout my season, I was rested for certain games and there wasn't too much emphasis that I was thrown out there every week."
Carter added: "I'm glad the process has finished and I'm just looking forward to getting back to what I love and that's playing rugby.
"I'm confident that people will read past the headlines and see that I've done nothing wrong."