SUFENTAź (sufentanil citrate) is a potent opioid analgesic chemically designated as N-[4-(methyoxymethyl)-1-[2-(2-thienyl)ethyl]-4-piperidinyl]-N-phenyl-propanamide:2-hydroxy-1,2,3-propanetricarboxylate (1:1) with a molecular weight of 578.68. The structural formula of SUFENTA (sufentanil citrate injection) is: