RQK rqk (2~{R})-2-oxidanyl-2-[(6~{S},9~{S},12~{S},15~{S},17~{S})-6,10,12,17-tetramethyl-3-methylidene-7-oxidanyl-2,5,8,11,14-pentakis(oxidanylidene)-13-oxa-1,4,7,10-tetrazabicyclo[13.3.0]octadecan-9-yl]ethanamide RQK