Population pharmacokinetics of nalbuphine in patients undergoing general anesthesia surgery

Purpose: The aim of this study was to build a population pharmacokinetics (PopPK) model of nalbuphine and to estimate the suitability of bodyweight or fixed dosage regimen. Method: Adult patients who were undergoing general anesthetic surgery using nalbuphine for induction of anesthesia were included. Plasma concentrations and covariates information were analyzed by non-linear mixed-effects modeling approach. Goodness-of-fit (GOF), non-parametric bootstrap, visual predictive check (VPC) and external evaluation were applied for the final PopPK model evaluation. Monte Carlo simulation was conducted to assess impact of covariates and dosage regimens on the plasma concentration to nalbuphine. Results: 47 patients aged 21-78 years with a body weight of 48-86 kg were included in the study. Among them, liver resection accounted for 14.8%, cholecystectomy for 12.8%, pancreatic resection for 36.2% and other surgeries for 36.2%. 353 samples from 27 patients were enrolled in model building group; 100 samples from 20 patients were enrolled in external validation group. The results of model evaluation showed that the pharmacokinetics of nalbuphine was adequately described by a two-compartment model. The hourly net fluid volume infused (HNF) was identified as a significant covariate about the intercompartmental clearance (Q) of nalbuphine with objective function value (OFV) decreasing by 9.643 (p < 0.005, df = 1). Simulation results demonstrated no need to adjust dosage based on HNF, and the biases of two dosage methods were less than 6%. The fixed dosage regimen had lower PK variability than the bodyweight regimen. Conclusion: A two-compartment PopPK model adequately described the concentration profile of nalbuphine intravenous injection for anesthesia induction. While HNF can affect the Q of nalbuphine, the magnitude of the effect was limited. Dosage adjustment based on HNF was not recommended. Furthermore, fixed dosage regimen might be better than body weight dosage regimen.

Glycopyrrolate versus atropine for preventing bradycardia induced by neostigmine injection after general anesthesia surgery: a randomized open, parallel-controlled multicenter clinical trial

OBJECTIVE

With atropine as a positive control, randomized controlled clinical trials were conducted to verify the efficacy of glycopyrrolate injection in preventing bradycardia caused by neostigmine.

METHOD

Patients undergoing elective general anesthesia and non-cardiac surgery were randomly divided into an experimental group (129 cases) and control group (127 cases) (ChiCTR2100046022, http://www.chictr.org.cn/showproj.aspx?proj=126075). At the end of the operation, the test group was given glycopyrrolate 6 ug/kg + neostigmine 0.04 mg/kg, and the control group was given atropine 0.016 mg/kg + neostigmine 0.04 mg/kg, bolus time 1 min, to antagonize muscle residual effects of relaxants. We compared the area under the time curve (AUC) of the difference between heart rate and baseline heart rate within 15 minutes of administration, the measured value of heart rate per minute, and the change in heart rate compared with baseline. We verified the safety of glycopyrrolate injection through laboratory tests, clinical symptoms, signs, and adverse events/serious adverse events.

RESULTS

The AUC of the experimental group's heart rate within 15 minutes after the administration was lower than the baseline heart rate change value, (P<005). The measured value of the heart rate at each time changed less than the control group; the experimental group's heart rate remained at the baseline level for longer than the control group (P<005). There was no significant difference in the incidence of adverse reactions between the two groups of patients (P>005).

CONCLUSION

Glycopyrrolate and atropine are safe to prevent heart rate slowing induced by the non-depolarizing muscle relaxant antagonist neostigmine, and glycopyrrolate is more conducive to maintaining a stable heart rate in patients.