Interesting…a randomised trial compared rocuronium mixed with saline against rocuronium mixed 1:1 with 8.4% sodium bicarbonate.
The principal finding was that rocuronium mixed with sodium bicarbonate 8.4% is more potent than that of rocuronium alone; it resulted in a more rapid onset time, and a prolonged recovery from the neuromuscular blockade.
It is likely that this effect is because the drug is weakly basic, and the change in pH from 4.01 to 7.78 seen after the addition of sodium bicarbonate 8.4% to rocuronium increases the amount of unionised rocuronium in the solution.
I suppose we could just give a bigger dose if we need to though.
Potency and recovery characteristics of rocuronium mixed with sodium bicarbonate
Anaesthesia. 2010;65(9):899–903