Tests on All Blacks Carter and Joe Rokocoko, as well as their Racing Metro team mate Juan Imhoff, after the Top 14 final they won against Toulon in June, showed the players had tested positive for corticoids, typically used to treat inflammation or joint pain.
"The reason for me taking, which I explained to the medical hearing that we had, was that I played the semi-final against Clermont," Carter told French newspaper Le Monde on Wednesday.
"The next day I had inflammation in my knee. I had the injection. I rested for two days. And then after that rest I was fit to play and I played.
"And I can’t see a problem with that because that’s all within the regulations. When you have an injury, you get your injury cured."
The FFR opened a disciplinary case against the club last week after Racing denied they had breached anti-doping rules and the players were cleared by the body's medical committee on Tuesday.
Carter argued that he had tried other treatments before receinving his injection.
"I tried ... these things to help reduce inflammation like icing and things… But you know, when there’s something available to use that’s not outside the antidoping regulations, then I think it would be silly not to use that," he said.
It was not the first time Carter had a corticoids injection as he revealed he received one during the 2015 World Cup.
"I had an injection after the injury, during the World Cup. I had an injury in the quarter finals and the next day I had an inflammation in the right knee as well," he said.
"I’ve had a few (in his career). When you have an injury, you want to cure the injury. It’s as simple as that."
(Reporting by Julien Pretot; Editing by Amlan Chakraborty)
