The present invention relates to crystalline forms of (1r,4r)-6"-fluoro-N,N-dimethyl-4-phenyl-4",9"-dihydro-3"l-l-spiro[cyclohexane-1,1 "-pyrano[3,4,b]indol]-4-amine, pharmaceutical compositions and medicaments comprising these modifications, the use of these modifications as well as to a process for the enrichment of them.