Sugammadex and neostigmine dose-finding study for reversal of residual neuromuscular block at a train-of-four ratio of 0.2 (SUNDRO20) ,

BackgroundThe aim of this dose-finding study was to evaluate the dose–response relationship of sugammadex and neostigmine to reverse a commonly observed level of incomplete recovery from rocuronium-induced neuromuscular block, that is, a train-of-four ratio (TOFR) ≥0.2.MethodsNinety-nine anaesthetized patients received rocuronium 0.6 mg kg−1 i.v. for tracheal intubation and, if necessary, incremental doses of 0.1–0.2 mg kg−1. Neuromuscular monitoring was performed by calibrated electromyography. Once the TOFR recovered to 0.2, patients were randomized to receive sugammadex (0.25, 0.5, 0.75, 1.0, or 1.25 mg kg−1 i.v.), neostigmine (10, 25, 40, 55, or 70 µg kg−1 i.v.), or saline (n+9 per group). Primary and secondary end points were the doses necessary to restore neuromuscular function to a TOFR≥0.9 with an upper limit of 5 and 10 min for 95% of patients, respectively.ResultsNeostigmine was not able to fulfil the end points. Based on the best-fitting model, the sugammadex dose estimation for recovery to a TOFR≥0.9 for 95% of patients within 5 and 10 min was 0.49 and 0.26 mg kg−1, respectively.ConclusionA residual neuromuscular block of a TOFR of 0.2 cannot be reversed reliably with neostigmine within 10 min. In the conditions studied, substantially lower doses of sugammadex than the approved dose of 2.0 mg kg−1 may be sufficient to reverse residual rocuronium-induced neuromuscular block at a recovery of TOFR≥0.2.Clinical trial registrationNCT01006720.