<prompt> Reason for preferring cis-Atracurium over Atracurium isDoes not undergo Hoffman eliminationSho and fast actionLesser provocation of histamine releaseEqual potency like Atracurium  <response>: Cis-Atracurium is a R enantiomer of Atracurium that does not provoke histamine release. Compared to Atracurium, Cis-Atracurium is: - 4 times more potent Slow in onset of action, but similar duration of action Not hydrolysed by plasma cholinesterase and has limited hepatic metabolism -- less amount of toxic metabolites are formed. Cis-Atra also undergoes Hoffman elimination Does not provoke histamine release, lesser side effects Cis-Atracurium is preferred skeletal muscle relaxant in elderly patients and for patients with liverkidney disease. Ref:- Goodman Gilman Pharmacological Basis of Therapeutics 13th Ed; Pg num:- 188 