Neutralized rocuronium (pH 7.4) before administration prevents injection pain in awake patients: a randomized prospective trial

Abstract

STUDY OBJECTIVE: To determine (1) the amount of 8.4% sodium bicarbonate (NaHCO(3)) to adjust the pH of rocuronium to 7.4 (neutralization), (2) to show whether neutralizing the pH of rocuronium can prevent pain, and (3) to confirm that rocuronium mixed with NaHCO(3) does not change the physical property and efficacy of rocuronium. DESIGN: Prospective studies. SETTING: University medical center. PATIENTS: 180 ASA physical status I and II women patients undergoing elective gynecologic surgery. INTERVENTIONS AND MEASUREMENTS: 60 patients were randomly allocated to group 1 (rocuronium only), group 2 (rocuronium 50 mg mixed with 0.9% NaCl 3 mL), and group 3 (rocuronium 50 mg mixed with 8.4% NaHCO(3) 3 mL). All patients received mixtures equal to 0.04 mg/kg of rocuronium and were asked to evaluate their pain with visual analog scale (VAS) and pain scores. In other settings, the onset time and duration of action of each group of rocuronium were measured. The dose of rocuronium required to produce a 50% twitch depression (ED(50)) was calculated. MAIN RESULTS: The amount of 8.4% NaHCO(3) needed to neutralize 50 mg of rocuronium was 3.1 +/- 0.3 mL. VAS scores were lower in group 3 than in groups 1 or 2 (P < 0.05). There were no differences in onset time, duration of action, or ED(50) values among the groups. CONCLUSIONS: Rocuronium neutralized with NaHCO(3) prevents intravenous injection pain. The physical and pharmacologic properties of rocuronium mixed with NaHCO(3) immediately before administration are not altered.