Eremenko, a key player for Finland, had sought to overturn the suspension and the case went to a CAS panel of arbitrators.
"The CAS Panel found that a two-year period of ineligibility was the appropriate sanction," the Swiss-based court said, setting the start date for the ban at Oct. 6, 2016.
UEFA, European football's governing body, has said Eremenko failed a doping test following CSKA's 2-2 Champions League draw against Bayer Leverkusen last September.
He was originally banned for 30 days in October, although no reason was given for the suspension at that time.
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The 30-year-old midfielder, who has played 73 times for Finland, had scored a 38th-minute equaliser against Leverkusen as CSKA fought back from two goals down to snatch a draw.
(Reporting by Michael Shields, editing by Ed Osmond)
