Saids and the World Anti-Doping Agency define substances of abuse as those "frequently abused in society outside of the context of sport".
"The player accepted responsibility for the doping offence and honoured his provisional suspension," Saids said.
Its statement added that Rabada was offered a chance to undertake a treatment programme, completing two sessions to bring his suspension to an end.
In revealing his suspension, Rabada, who initially said he was leaving the IPL for "personal reasons", said he was "deeply sorry to all those that I have let down".
"I will never take the privilege of playing cricket for granted," he said. "This privilege is much larger than me. It goes beyond my personal aspirations."
Rabada played twice for Gujarat Titans in this year's IPL, most recently on 29 March. The Titans, currently fourth in the standings, playing a crucial match against Mumbai Indians on Tuesday.