Super League side St Helens have seen their appeal against Ben Barba's 12-match suspension rejected.
Barba was released by NRL side Cronulla Sharks and received the ban after testing positive for cocaine in November.
He signed for Top 14 rugby union club Toulon in February, but was sacked in May having played just four games.
St Helens then made the move to sign Barba last month, but will have to wait until August to benefit from his services after an independent tribunal upheld his suspension.
Barba has already served five games of the ban, and will be available for selection from August 28.