Rocuronium is a monoquaternary steroid analogue of vecuronium was designed to provide a rapid onset of action. Rocuronium is the fastest acting nondepolarizing muscle relaxant. Rocuronium (at a dose of 0.9-1.2 mg/kg) has an onset of action that approaches succinylcholine (60-90 s), making it a suitable alternative for rapid-sequence induction. Rocuronium is less potent than most other steroidal muscle relaxants (potency appears to be inversely related to speed of onset). Because rocuronium does not have active metabolites, it may be a better choice than vecuronium for prolonged infusions. Its duration of action is not significantly affected by renal disease, but it is modestly prolonged by severe hepatic failure and pregnancy. Ref: Morgan, Jr. G.E., Mikhail M.S., Murray M.J. (2006). Chapter 9. Neuromuscular Blocking Agents. In G.E. Morgan, Jr., M.S. Mikhail, M.J. Murray (Eds), Clinical Anesthesiology, 4e.