| BackgrooundAlfentanil is a highly selective μ-opioid agonist,which is widely used as an analgesic in general anesthesia for various surgical procedures.The analgesic and sedative effects of alfentanil can efffectively inhibit various stress reactions arising from induction of anesthesia and surgical stimulation Alfentanil has low overall clearance,small volume of distribution on the body surface,and side effects such as respieatory depression,reduced gastrointestinal motility and bradycardia Alfentanil has a relatively stable dose-related half-life and no accumulation the body after continuous infusion,so it can be applied to target-controlled infusion,and the study ofthe accuracy of alfentanil target-controlled infusion system can better improve the safety of clinical application by controlling the appropriate blood concentration.ObjectiveAn ultra-performanoe liquid chromatogaphy and tandem mass spectrometry(UPLC-MS/MS)method was developed to determine human plasma alfentanil concentrations and to evaluate the accuracy of the target-control infusion(TCI)system of alfentanil under general anesthesia with propofol in order to guide the clinical use of the drug.Methods1.Determination of human plasma alfentanil plasma concentration by ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS)was used to determine the plasma concentration of human plasma alfentanil and to fit a standard curve to determine the detection limit,precision and recovery.(1)Standard curve preparationAlfentanil standard 10 mg(in pure form)was accurately weighed,dissolved in acetonitrile in a 10 mL volumetric flask and diluted to obtain a concentration of 1000 μg·L-1 alfentanil standard stock solution,diluted with methanol and fixed in a 10 mL volumetric flask to obtain the corresponding concentration of alfentanil standard working solution.(2)Standard curve evaluationThe recovery of the analyte recovered from the matrix of the biological sample divided by the response value ganerated by the standard is the extraction recovery of the analyte,the proportion of the analyte extracted from the test biological sample for analysis.The extraction recovery should be examined for high,medium and low concentrations and the results should be consistent,accurate and reproducible.The recovery is calculated as:Recovery(R)=Assay value/Spiked amount*100%;Accuracy is the degree of dispersion of a series of measured values for the same concentration of sample in the same medium under defined analytical conditions.The of the method is examined using the inter-day precision and intra-day precision of the quality control samples;Specificity is the ability of an analytical method to accurately and specifically determine an analyte in the presence of interfering components in the sample.The specificity of the method was examined using the inter-batch relative standard deviation ofthe QC samples.2.Accuracy evaluation of target-controlled infusion system of alfentanilFifteen patients,six males and nine females,aged 18～65 years with BMI 19～24 kg·m-2 and ASA class Ⅰ to Ⅱ,underwent laparoscopic cholecystectomy under elective general anesthesia After admission,the patients’ heart rate(HR),noninvasive blood pressure(NBP),electrocardiogram(ECG),pulse oximetry(SpO2),and Narcotrend index were monitored continuously,and the patients were preoxygenated with a face mask for 5 min before induction,with an oxygen flow rate of 5～6 L·min-1.The propofol and alfentanil target-controlled infusion models were used for propofol and alfentanil targetcontrolled infusion models with embedded Marsh and Hudson pharmacokinetic parameters(TCI-CP 800TC,Beijing Silugao Medical Technology Co.Ltd.).When the Narcotrend index reached below Di,cis-ateacurium 0.2～0.3 mg·kg-1 was injected,and the target plasma concentration of propofol and alfentanil was set to 3.0～4.0 μg·mL-1 and 100 μg·L-1,respectively，during induction.The tidal volume was set at 4～6 mL·kg-1,the respiratory rate at 12～14 times·min-1,the inspiratory-toexpiratory ratio at 1:15～1:2,the oxygen flow rate at 1～2 L·min-1,and the respiratory parameters were adjusted to maintain the airway pressure at 15 cm H2O.The concentrations of Cp 2.5～3.0μg·mL·-1 and 100 μg·L-1 and dexmedetomidine were infused at a constant rate of 0.2～0.8μg·kg-1·h-1.5 mL of radial artery blood was collected before(blank plasma)and 2 min,5 min,10 min,15 min,20 min,30 min 45 min and 60 min after TCI of alfentanil,and the established UPLC-MS/MS method was applied to detect plasma alfentanil concentrations and analyze the difference between the predicted plasma concentration(Cp)and the measured plasma concentration(Cm)of alfentanil,and calculate the execution error(PE),deviation(median performance error,MDPE),precision(median absolute performanoe error,MDAPE),wobble and divergence of the TCI system based on the diffeence between alfentanil Cp and Cm error.Result1.Determination of human plasma alfentanil plasma concentration by UPLC-MS/MS(1)The linearity was good in the concentration range of 0.1 μg·L-1 to 100 μg·L-1 with a concention coefficient of 0.999;(2)The limits of detection(LOD)and limits of quantification(LOQ)of the method were 0.1μg·L-1 and 0.3μg·L-1,respectively;(3)The mean intra day recoveries of 92.8%±3.9%and inter-day recoveries of 92.0%±3.8%for the three concentrations of alfentanil 0.3 μg·L-1,5.0μg·L-1 and 20.0μg·L-1,respectively;(4)Intra-day precision(Intha-day precision)and inter-day precision(Inter-day precision)were 6.28%± 032%and 92.0%±3.06%,respectively.The relative standard deviation(i.e.,precision)between batches is 6.6%.2.Accuracy evaluation of target-controlled infusion system of alfentanil(1)At the predicted Cp concentration of alfentanil of 100 μg·L-1,the mean Cm values measured at 1 min 2 min and 5 min after TCI administration were 118.9μg·-1,142.2 μg·L-1 and 1373 μg·L-1,which were significantly higher than the predicted Cp of 100 μg·L-1 by 18.9%,422%and 373%,respectively.The mean TCI 30 min and 60 min measured Cm values were 1162μg·L-1 and 109.8 μg·L-1,respectively,which were higher than the predicted Cp 100 μg·L-1 by 16.2%and 9.8%,with no statistically significant difference(P<0.05).(2)The mean value of the overall blood sample predicted value of Cm was 123.5 μg·L-1 for the predicted concentration of alfentanil plasma Cp concentration of 100 μg·L-1,which was 23.5%higher than the predicted value of Cp 100 μg·L-1 with no statistically significant difference,(p>0.05).(3)During the infusion of alfentanil plasma predicted concentration Cp concentration at 100 μg-L-1,the TCI system deviation was-14 26%absolute value close to 15%,the oscillation was 21.09%,the system deviation was in accordanoe with the clinical criteria,the oscillation was slightly above the normal range(>20%),the accuracy of the TCI system was 20.17%,the dispersion was-0.68%-h-1.The absolute values of the accuracy of the TCI system were<30%and the absolute values of the dispersion were<1%-h-1,indicating that the TCI system has good stability and can be adjusted proportionally to the plasma target concentration according to clinical needsConclusion1.UPLC-MS/MS determination of human plasma alfentanil plasma concentrationUPLC-MS/MS for the determination of alfentanil in human plasma is sensitive,selective and accurate and can be used for clinical determination of alfentanil plasma concentrations.2.Accuracy evaluation of alfentanil TCI systemThe TCI system deviation of-14.26%,accuracy of 20.17%,oscillation of 21.09%and dispersion of-0.68%·h-1 at a predicted alfentanil plasma concentration Cp concentration of 100 μg·L-1 met the criteria for clinical anesthesia application and confirmed that the embedded Hudson pharmacokinetic parameters of alfentanil TCI system can maintain stable plasma concentrations doring continuous infusion It is suitable for national target-controlled infusion. |
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