Gas chromatographic-mass spectrometric assay for rocuronium with potential for quantifying its metabolite, 17-desacetylrocuronium, in human plasma

Rapid detection of rocuronium based on host/guest complex between a pyrene derivative and sugammadex

Rocuronium is widely used in surgery as a neuromuscular relaxant, but it has been difficult to accurately control its specific dosage in clinical operation. Therefore, the development of fast and instant rocuronium detection methods has important application value for reducing risks and safeguarding health. In this study, N, N, N-trimethyl-4-(pyrene-1-butyl)-ammonium bromide (PyBTA) was designed as a probe to detect rocuronium rapidly. The method relied on replacing PyBTA in sugammadex with rocuronium to induce changes in fluorescence intensity of PyBTA, thereby realizing quantitative detection. Its sensing performance and detection mechanism were explored systematically by spectroscopy. The linear range of this method was 0.5-10 μM and the detection limit of it was 0.3 μM. In addition, we confirmed that the host-guest interaction among PyBTA, sugammadex, and rocuronium was mainly driven by electrostatic and hydrophobic interactions.

An analytical strategy for quaternary ammonium neuromuscular blocking agents in a forensic setting using LC-MS/MS on a tandem quadrupole/time-of-flight instrument

An analytical strategy is described for analyzing quaternary ammonium neuromuscular blocking agents in a wide variety of biological specimens in a forensic setting. Neuromuscular blocking agents such as succinylcholine, pancuronium, and tubocurarine, often used as paralytic agents during surgery, are occasionally suspected as paralytic poisoning agents involved in suspected homicide and suicide cases. Because suspicion in such cases can develop slowly, the age, nature, and quality of available specimens varies greatly. The compounds are challenging analytically because of their simultaneous precharged yet lipophilic character. An analytical strategy has been devised for extracting these compounds from complex matrices using a combination of a modified Bligh and Dyer liquid-liquid extraction (used in reverse) followed by reverse-phase ion pairing solid-phase extraction using heptafluorobutyric acid as an ion pairing reagent. Final analysis is by LC-MS/MS using a tandem quadrupole orthogonal acceleration time of flight instrument (Q-TOF) with repetitive product ion scanning at high resolution. Native and spiked specimens are compared for both quantitative and especially qualitative purposes. The method has been applied to a wide variety of fluid and tissue specimen types, including numerous specimens from exhumation autopsies. For most specimens, detection limits are in the 2 to 10 ng/g range. Succinylmonocholine has been demonstrated to be present at low levels in normal posthumous kidney and liver. The Q-TOF is an excellent platform for forensic analytical investigations. This analytical strategy should also be applicable to other problematic analytes and sample matrices.

Influence of acute normovolaemic haemodilution on the dose-response relationship, time-course of action and pharmacokinetics of rocuronium bromide

BACKGROUND

Acute normovolaemic haemodilution (ANH) is an effective strategy for avoiding or reducing allogeneic blood transfusion. We aimed to study its effect on the pharmacological profile of rocuronium.

METHODS

In two study centres, 28 patients undergoing major surgery with ANH were matched with 28 control patients. In the dose-response groups, using the mechanomyograph, neuromuscular block of six consecutive incremental doses of rocuronium 50 microg kg(-1), followed by 300 microg kg(-1), was evaluated. In the pharmacokinetics groups, serial arterial blood samples were withdrawn for rocuronium assay after a single dose of rocuronium 600 microg kg(-1).

RESULTS

ANH resulted in a shift to the left of rocuronium dose-response curve. Rocuronium effective dose(95) (ED(95)) was 26% lower (P<0.05) in the ANH group [283.4 (92.0) microg kg(-1)] compared with the control group [383.5 (127.3) microg kg(-1)]. Times from administration of last incremental dose until 25% of first response of train-of-four (TOF) recovery (Dur(25)) and 0.8 TOF ratio recovery (Dur(0.8)) were 28% longer in the ANH group [39.9 (8.4), 66.7 (14.2) min] compared with the control group [31.1 (6.6), 52.1 (15.8) min] (P<0.01, P<0.05), respectively. Volume of distribution was higher (P<0.01), central clearance was lower (P<0.05) and terminal elimination half-life was longer (P<0.0001) in the ANH group [234.97 (47.11) ml kg(-1), 4.70 (0.94) ml kg(-1) min(-1), 77.29 (12.25) min] compared with the control group [181.22 (35.73) ml kg(-1), 5.71 (1.29) ml kg(-1) min(-1), 56.86 (10.05) min, respectively].

CONCLUSION

ANH resulted in prolongation of rocuronium time-course of action, thus careful monitoring of neuromuscular block is recommended in patients who undergo ANH.

The effect of bi-level positive airway pressure mechanical ventilation on gas exchange during general anaesthesia

BACKGROUND

Atelectasis may occur and ventilation-perfusion mismatch may increase during general anaesthesia with neuromuscular paralysis and mechanical ventilation, though preservation of some intermittent muscle contraction might mitigate this process. There is still no ideal manoeuvre to minimize such mismatch or atelectasis. Bi-level positive airway pressure (BiPAP) ventilation adjusts to extra breaths and improves gas exchange during recovery of diaphragm function after neuromuscular paralysis. We hypothesize that BiPAP ventilation may limit the development of pulmonary shunt and may improve ventilation-perfusion mismatch when compared with standard IPPV, with or without PEEP when neuromuscular paralysis has been used during surgery.

METHODS

Twenty ventilated patients either on BiPAP or IPPV with or without PEEP were studied randomly using the multiple inert gas elimination technique (MIGET) at 60 and 120 min after rocuronium at induction and after 60 min. Non-invasive cardiac output (NICO) monitoring and plasma concentrations of rocuronium were measured. We compared the data of MIGET, gas exchange, haemodynamic variables and pulmonary mechanics measurements between the different ventilatory modes.

RESULTS

Intrapulmonary shunt (blood flow to V(A)/Q < 0.005) did not increase at 60 min of anaesthesia in any of the different ventilation modes compared with the shunt value before anaesthesia. Log standard deviation of perfusion increased in IPPV, with and without PEEP groups, compared with the baseline (P< 0.05) but did not increase in the BiPAP group. BiPAP ventilation generated a higher level of Pa(O2)than IPPV with or without PEEP (P<0.05).

CONCLUSION

BiPAP ventilation was beneficial in decreasing ventilation-perfusion mismatch and improving oxygenation when compared with conventional IPPV (with or without PEEP).

Rocuronium infusion requirements and plasma concentrations at constant levels of neuromuscular paralysis during three phases of liver transplantation

STUDY OBJECTIVE

To develop a rapid online test of graft liver function during liver transplantation.

DESIGN

Prospective, observational study.

SETTING

University hospital transplant unit.

PATIENTS

17 adult patients with end-stage liver disease who underwent liver transplantation surgery.

INTERVENTIONS

Rocuronium infusion dose requirements and plasma concentrations to maintain constant levels of neuromuscular paralysis during three phases of liver transplantation and their relationship with early postoperative liver function tests were studied.

MEASUREMENTS

Infusion dose requirements of rocuronium, assay of rocuronium plasma concentrations using gas chromatography-mass spectrometry, and intensity of neuromuscular blockade were measured.

MAIN RESULTS

A 24% decrease in rocuronium infusion requirements was observed during the an-hepatic phase. Rocuronium requirement during the neohepatic phase was increased only modestly or remained unchanged in 14 of the 16 patients who had normal graft function in the immediate postoperative period. Rocuronium plasma concentrations for maintaining constant levels of paralysis were significantly lower during the neohepatic phase than during the paleohepatic and anhepatic phases, indicating that there is likely to be a change in pharmacodynamics during this phase. Significant reduction in rocuronium infusion requirements during the neohepatic phase was observed in the only patient who had poor graft function in the early postoperative stage, suggesting that the reduced infusion requirement to maintain a constant neuromuscular paralysis may be related to the functional state of the graft liver after reperfusion.

CONCLUSIONS

A significant reduction in rocuronium infusion requirement during the neohepatic phase may be suggestive of impaired organ function after reperfusion of the graft liver. Rocuronium may serve as a potential online indicator of graft liver function during liver transplantation by measurement of its infusion requirements during transplantation.

Rocuronium plasma concentrations during three phases of liver transplantation: relationship with early postoperative graft liver function

BACKGROUND

Previous studies have suggested that neuromuscular blocking agents might be used to assess liver function during liver transplantation. This study examines changes in rocuronium plasma concentration during liver transplantation, to assess graft function.

METHODS

A constant-rate infusion of rocuronium was administered to 17 adult patients undergoing liver transplantation. Blood samples were taken at 30-min intervals throughout the procedure, which was divided into three phases: paleo-, an-, and neohepatic. Assay of plasma concentrations of rocuronium was by a gas chromatographic-mass spectrometry technique. Postoperative liver function was followed for up to five days by measuring plasma aminotransferases.

RESULTS

In 14 of the 15 patients who survived the transplantation procedure, there was a 7-50% decrease in rocuronium concentration during the neohepatic phase compared with the anhepatic phase. In contrast, rocuronium concentrations increased in the two patients who died after surgery, one as a result of primary non-function and one from massive bleeding. In one patient who survived there was no change in rocuronium concentration. The increase in plasma rocuronium concentration during the neohepatic phase in the two patients who died was consistent with high levels of plasma aminotransferases.

CONCLUSIONS

Comparison of changes in plasma rocuronium concentration during the neohepatic phase with early postoperative liver function tests suggests the potential use of rocuronium as a pharmacokinetic probe for predicting liver function during liver transplantation. Further study of rocuronium's potential as an intraoperative pharmacodynamic probe of liver function by measuring neuromuscular paralysis is suggested.

Determination of Rocuronium bromide by hydrophilic interaction liquid chromatography (HILIC)

A new method involving hydrophilic interaction liquid chromatography (HILIC) has been developed for determination of rocuronium bromide in presents of its main impurities (impurity A and impurity C), which are also its main degradation products, in solution for injection. The influence of the critical chromatographic parameters such as content of acetonitrile in the mobile phase, ionic strength and pH value of the buffer used in the mobile phase were investigated using the Design of experiments approach (DoE). The mechanism of retention of rocuronium bromide on bare silica column was also investigated. Optimal chromatographic conditions were obtained using mixture of acetonitrile and ammonium formate (107.5mM, pH 7.0) in ratio 90:10 as a mobile phase. The validation results have shown that the method is suitable for determination of rocuronium bromid in solution for injection.