Rahul's reports came positive on Friday night after he was caught in a rave party by police along with South African cricketer and his Pune team-mate Wayne Parnell on May 20. The duo was among the 44 who attended a rave party at Oakwood Premier Hotel in Mumbai's Juhu.
Amre, who has coached Rahul during IPL, backed the legspinner and said he never consumed alcohol. He also added that Rahul is a vegetarian.
"It is quite shocking that Rahul has tested positive. The boy has a very simple lifestyle. It is hard to believe that he has done drugs. I have not even seen him consuming alcohol," Amre told the SUNDAY MiD Day on Sunday.
The former India batsman said he does not know how the Board of Control for Cricket in India (BCCI) would treat this case.
"It will definitely be a setback for him. It remains to be seen whether he will be sent back home (from Sri Lanka, where he is touring with the Indian team scheduled to play five ODIs and a one-off T20 international). I don't know how the BCCI (Board of Control for Cricket in India) will treat this matter, but before that, Rahul will have to go through the Mumbai Police's procedures and that is quite a tough task," Amre told the newspaper.
Rahul was not picked for the firt One Day International between India and Sri Lanka on Saturday in Hambantota.
India will play their second ODI against Sri Lanka on July 24, Tuesday.