Lyoto Machida firmly disagrees with the length of his USADA suspension.

In a statement posted Friday to his Facebook page, the former UFC light heavyweight champion said he did not know the substance he was sanctioned for was prohibited, because information from USADA has been "unclear." Machida said he was using the substance, 7-keto-dehydroepiandrosterone (DHEA), to reduce stress, not for performance enhancement.

Machida was suspended 18 months by USADA, the UFC's anti-doping partner, it was announced Wednesday. In April, Machida admitted to using 7-keto-DHEA and later had an elevated 7β-hydroxy-DHEA to DHEA ratio in a drug test, per USADA.

"By no means did I imagine that the substance could be banned by USADA," Machida wrote in the statement. "The information relayed to the athletes were insufficient. The full list of all prohibited supplements, in an easier way to read, I only received via text message, this week, on the day after my suspension. The previous formats were not clear. To teach and educate should also be the duties of an institution that is committed to the advancement of a clean sport and not only for punishing."

Machida, 38, was facing a two-year suspension, but it was bumped down to 18 months by USADA because Machida was forthright in his admission and cooperated with the investigation, the agency's release stated. Machida didn't think it should have been that long.

"I reiterate that I never had any problem in all my career and always collaborated with USADA," he wrote. "I hoped that the fact that I spontaneously declared which substance I ingested would be taken into consideration. I have always been an honest and transparent person, something that I learned since a young age from my father Yoshizo.

"Unfortunately USADA did not see my honesty, which was always my priority. I believe that if I had been tried by the athletic commission I would have been heard and would have had a different outcome."

Machida (22-7) is eligible to return to the UFC in October 2017. The suspension is retroactive to April 6, 2016 when he made his admission during a USADA sample collection. "The Dragon" was pulled out of a fight with Dan Henderson at UFC on FOX 19 just three days prior to the contest after being hit with a provisional suspension from USADA.

The substance 7-keto-DHEA is listed under the "anabolic agents" portion of the WADA code, which is why it carries a two-year maximum suspension from USADA. It has previously been characterized as a steroid, though questions have arisen as to how much performance-enhancing qualities it has. The substance has shown the ability to increase metabolism and weight loss.

Machida argued that 7-keto-DHEA can be found on store shelves and is easily accessible to the public.

"The supplement I took, 7-Keto, can be sold anywhere, which [reinforces] the fact that it's not used for performance enhancement," Machida wrote. "As I said before, I took it to lower stress levels, as I was coming off two losses and had not fought in some time."