All of the statements about skeletal muscle relaxants are true, EXCEPT:

Rocuronium does not undergo any metabolism and is excreted unchanged through bile and urine. 90% of injected dose of mivacurium is hydrolysed by pseudocholinesterase to mivacurium monoester and amino alcohol. 10% of it is excreted unchanged in urine. Pancuronium stimulates the sympathetic nervous system by inhibiting the reupake and increasing the release of catecholamines at the nerve endings and by the muscarinic receptor blockade action. Atracurium is degraded by Hoffman's elimination in addition to that by cholinesterase.