Figure 13-23 Degradation pathways of atracurium. The major metabolite, laudanosine, is excreted in urine and bile. Laudanosine is a tertiary amine that may enter the central nervous system. Less than 10% of atracurium is excreted as the parent compound. (Redrawn from Basta SJ, Ali HH, Savarese JJ, et al: Clinical pharmacology of atracurium besylate [BW 33A]: A new non-depolarizing muscle relaxant. Anesth Analg 61:723–729, 1982.)