Neuromuscular and cardiovascular advantages of combinations of mivacurium and rocuronium over either drug alone

We investigated isobolic mixtures of mivacurium and rocuronium to determine if the combination offered any advantages over either drug alone. We used five dose regimens to achieve ED95 x 2: [(1.5 x ED95 mivacurium) + (0.5 x ED95 rocuronium); (1 x ED95 mivacurium) + (1 x ED95 rocuronium); (0.5 x ED95 mivacurium) + (1.5 x ED95 rocuronium); (2 x ED95 mivacurium); (2 x ED95 rocuronium)]. We studied onset time, duration of block, recovery of block, arterial blood pressure and heart rate. Mivacurium alone produced the block of shortest duration (p < 0.001). Onset time was shortest in the rocuronium alone group and was significantly faster in all the rocuronium treated groups compared to mivacurium alone (p < 0.001). Arterial blood pressure and heart rate decreased transiently in the mivacurium alone group but not in the other groups. These results demonstrate increased cardiovascular stability and more rapid onset of block with combinations of mivacurium and rocuronium without significant prolongation of the block.