Determination of total and unbound sufentanil in human plasma by ultrafiltration and LC–MS/MS: Application to clinical pharmacokinetic study

Rapid Determination of Sufentanil in Human Plasma by UHPLC-QqQ-MS-MS

This paper presents a rapid, sensitive and precise method developed and validated for the quantification of sufentanil in biological samples using ultra-performance liquid chromatography coupled with QqQ-MS-MS. Plasma samples were extracted with simple and fast liquid-liquid extraction (ethyl acetate, pH 9). Calibration curve showed linearity in the concentration range of 0.005-30 µg/L. The lower limit of quantification was 0.010 µg/L. The most important method features are low lower limit of quantification value, simple plasma extraction and small sample volume. This method is suitable not only for evaluation of the pharmacokinetics, toxicology, bioavailability and clinical pharmacology of sufentanil but also for the detection and identification of this compound in human plasma samples for forensic purposes.

Relationship Between the Free and Total Methotrexate Plasma Concentration in Children and Application to Predict the Toxicity of HD-MTX

High-dose methotrexate (HD-MTX) can be highly effective as well as extremely toxic. Many drug molecules can bind to plasma proteins to different extents in vivo, whereas only the free drug can reach the site of action to exert a pharmacological effect and cause toxicity. However, free MTX concentrations in plasma have not been reported. Traditional analyses of free drugs are both cumbersome and inaccurate. We collected 92 plasma samples from 52 children diagnosed with ALL or NHL or other lymphomas that were treated with HD-MTX. The hollow fiber centrifugal ultrafiltration (HFCF-UF) was used to prepare plasma samples for analysis of the free MTX concentration. Protein precipitation was employed to measure the total MTX concentration. The HFCF-UF is a simple method involving a step of ordinary centrifugation; the validation parameters for the methodological results were satisfactory and fell within the acceptance criteria. A linearity coefficient r² of 0.910 was obtained for the correlation between the free and total MTX plasma concentrations in 92 plasma samples. However, the free and total MTX concentrations was only weakly correlated in 16 clinical plasma specimens with total MTX concentrations >2 μmol L⁻¹ (r² = 0.760). Both the free and total MTX concentrations at 42 h were negatively correlated with the creatinine clearance (CCr) level (P = 0.023, r = −0.236 for total MTX and P = 0.020, r = −0.241for free MTX, respectively). The free MTX concentration could not be accurately estimated from the total MTX concentration for patients with high MTX levels which are conditions under which toxic reactions are more likely to occur. High plasma MTX levels could become a predictor of the occurrence of MTX nephrotoxicity to draw people's attention. The proposed HFCF-UF method is a simple and accurate way to evaluate efficacy and toxicity in clinical therapeutic drug monitoring.

Postoperative pain therapy with hydromorphone; comparison of patient-controlled analgesia with target-controlled infusion and standard patient-controlled analgesia: A randomised controlled trial

BACKGROUND

The challenge of managing acute postoperative pain is the well tolerated and effective administration of analgesics with a minimum of side effects. The standard therapeutic approach is patient-controlled analgesia (PCA) with systemic opioids. To overcome problems of oscillating opioid concentrations, we studied patient-controlled analgesia by target-controlled infusion (TCI-PCA) as an alternative.

OBJECTIVE

To compare efficacy, safety and side effects of standard PCA with TCI-PCA for postoperative pain therapy with hydromorphone.

DESIGN

Single-blinded, randomised trial.

SETTING

University Hospital, Germany from December 2013 to April 2015.

PARTICIPANTS

Fifty adults undergoing cardiac surgery.

INTERVENTIONS

Postoperative pain therapy on the ICU was managed with intravenous (i.v.) hydromorphone and patients randomised to TCI-PCA with target plasma concentrations between 0.8 and 10 ng ml, or PCA with bolus doses of 0.2 mg. Pain was regularly assessed using the 11-point numerical rating scale (NRS). Blood pressure, heart rate, oxygen saturation and cardiac output were continuously monitored, and adverse events were registered throughout the study.

MAIN OUTCOME MEASURES

NRS pain ratings, hydromorphone doses, haemodynamic effects and side effects.

RESULTS

NRS pain ratings, total doses of hydromorphone and haemodynamic data did not differ significantly between TCI-PCA and PCA. The number of bolus doses during PCA was significantly higher than the number of target increases during TCI-PCA (P = 0.006). The number of negative requests was also significantly higher during PCA than during TCI-PCA (P = 0.02). The respiratory rate on the first postoperative morning was 25 ± 6 min during TCI-PCA, compared with 19 ± 4 min during PCA (P = 0.022). Nausea occurred in 30% after TCI-PCA and 24% after PCA (P = 0.46).

CONCLUSION

TCI-PCA was effective and well tolerated in acute postoperative pain management after cardiac surgery. Further studies are needed to evaluate this approach in clinical practice.

TRIAL REGISTRATION

EudraCT Number: 2013-002875-16, and ClinicalTrials.gov Identifier: NCT02035709.

Ten Years of Fentanyl-like Drugs: a Technical-analytical Review

Synthetic opioids, such as fentanyl and its analogues, are a new public health warning. Clandestine laboratories produce drug analogues at a faster rate than these compounds can be controlled or scheduled by drug agencies. Detection requires specific testing and clinicians may be confronted with a sequence of severe issues concerning the diagnosis and management of these contemporary opioid overdoses. This paper deals with methods for biological sample treatment, as well as the methodologies of analysis that have been reported, in the last decade, in the field of fentanyl-like compounds. From this analysis, it emerges that the gold standard for the identification and quantification of 4-anilinopiperidines is LC-MS/MS, coupled with liquid-liquid or solid-phase extraction. In the end, the return to the scene of illicit fentanyls can be considered as a critical problem that can be tackled only with a global multidisciplinary approach.

Simultaneous quantification of fentanyl, sufentanil, cefazolin, doxapram and keto-doxapram in plasma using liquid chromatography-tandem mass spectrometry

A simple and specific UPLC–MS/MS method was developed and validated for simultaneous quantification of fentanyl, sufentanil, cefazolin, doxapram and its active metabolite keto‐doxapram. The internal standard was fentanyl‐d5 for all analytes. Chromatographic separation was achieved with a reversed‐phase Acquity UPLC HSS T3 column with a run‐time of only 5.0 min per injected sample. Gradient elution was performed with a mobile phase consisting of ammonium acetate or formic acid in Milli‐Q ultrapure water or in methanol with a total flow rate of 0.4 mL min⁻¹. A plasma volume of only 50 μL was required to achieve adequate accuracy and precision. Calibration curves of all five analytes were linear. All analytes were stable for at least 48 h in the autosampler. The method was validated according to US Food and Drug Administration guidelines. This method allows quantification of fentanyl, sufentanil, cefazolin, doxapram and keto‐doxapram, which is useful for research as well as therapeutic drug monitoring, if applicable. The strength of this method is the combination of a small sample volume, a short run‐time, a deuterated internal standard, an easy sample preparation method and the ability to simultaneously quantify all analytes in one run.

Influence of Cardiac Output on the Pharmacokinetics of Sufentanil in Anesthetized Pigs

BACKGROUND

Sufentanil is used for general anesthesia and analgesia. The study aim was to determine the effect of pharmacologically induced changes in cardiac output on the pharmacokinetics of sufentanil in anesthetized pigs.

METHODS

Twenty-four pigs were randomly assigned to low, high, and control cardiac output groups. Cardiac output was decreased or increased from baseline by at least 40%, or maintained within ± 10% of baseline, respectively. Sufentanil was administered as a bolus followed by a continuous infusion for 120 min. Timed arterial samples were drawn for sufentanil concentration measurements.

RESULTS

Data from 20 animals were analyzed. The cardiac outputs (means ± SD) were 2.9 ± 0.7, 5.4 ± 0.7, and 9.6 ± 1.6 l/min in the low, control, and high cardiac output groups, respectively. The parameters of the two-compartment pharmacokinetic model for these cardiac outputs were: CL1: 0.9, 1.2, and 1.7 l/min; CL2: 0.9, 3.1, and 6.9 l/min; V1: 1.6, 2.9, and 5.2 l; and V2: 27.5, 47.0, and 79.8 l, respectively. Simulated sufentanil doses to maintain a target plasma concentration of 0.5 ng/ml for 3 h were 99.5, 128.6, and 157.6 μg for cardiac outputs of 3, 5, and 7 l/min, respectively. The context-sensitive half-times for these cardiac outputs increased from 3.1 to 19.9 and 25.9 min, respectively.

CONCLUSIONS

Cardiac output influences the pharmacokinetics of sufentanil. Simulations suggest that in the case of increased cardiac output, the dose should be increased to avoid inadequate drug effect at the expense of prolonged recovery, whereas for low cardiac output the dose should be reduced, and a faster recovery may be expected.

Pharmaceutical applications of affinity-ultrafiltration mass spectrometry: Recent advances and future prospects

The immunoaffinity of protein with ligand is broadly involved in many bioanalytical methods. Affinity-ultrafiltration mass spectrometry (AUF-MS), a platform based on interaction of protein-ligand affinity, has been developed to fish out interesting molecules from complex matrixes. Here we reviewed the basics of AUF-MS and its recent applications to pharmaceutical field, i.e. target-oriented discovery of lead compounds from combinatorial libraries and natural product extracts, and determination of free drug concentration in biosamples. Selected practical examples were highlighted to illustrate the advances of AUF-MS in pharmaceutical fields. The future prospects were also presented.

Patient-controlled Analgesia with Target-controlled Infusion of Hydromorphone in Postoperative Pain Therapy

Background

Patient-controlled analgesia (PCA) is a common method for postoperative pain therapy, but it is characterized by large variation of plasma concentrations. PCA with target-controlled infusion (TCI-PCA) may be an alternative. In a previous analysis, the authors developed a pharmacokinetic model for hydromorphone. In this secondary analysis, the authors investigated the feasibility and efficacy of TCI-PCA for postoperative pain therapy with hydromorphone.

Methods

Fifty adult patients undergoing cardiac surgery were enrolled in this study. Postoperatively, hydromorphone was applied intravenously during three sequential periods: (1) as TCI with plasma target concentrations of 1 to 2 ng/ml until extubation; (2) as TCI-PCA with plasma target concentrations between 0.8 and 10 ng/ml during the following 6 to 8 h; and (3) thereafter as PCA with a bolus dose of 0.2 mg until the next morning. During TCI-PCA, pain was regularly assessed using the 11-point numerical rating scale (NRS). A pharmacokinetic/pharmacodynamic model was developed using ordinal logistic regression based on measured plasma concentrations.

Results

Data of 43 patients aged 40 to 81 yr were analyzed. The hydromorphone dose during TCI-PCA was 0.26 mg/h (0.07 to 0.93 mg/h). The maximum plasma target concentration during TCI-PCA was 2.3 ng/ml (0.9 to 7.0 ng/ml). The NRS score under deep inspiration was less than 5 in 83% of the ratings. Nausea was present in 30%, vomiting in 9%, and respiratory insufficiency in 5% of the patients. The EC50 of hydromorphone for NRS of 4 or less was 4.1 ng/ml (0.6 to 12.8 ng/ml).

Conclusion

TCI-PCA with hydromorphone offered satisfactory postoperative pain therapy with moderate side effects.

Simultaneous detection of ketamine, lorazepam, midazolam and sufentanil in human serum with liquid chromatography-tandem mass spectrometry for monitoring of analgosedation in critically ill patients

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the determination and quantification of four predominantly used analgosedatives in the intensive care unit: ketamine, lorazepam, midazolam and sufentanil in human serum. The extraction procedure consisted of protein precipitation of serum samples with acetonitrile and subsequent centrifugation. D₅-fentanyl and D₄-midazolam served as internal standards (ISTD). Separation of analytes was performed with a Hypersil C18 column and a mobile phase with acetonitrile and 0.1% formic acid (60/40, v/v) under isocratic conditions at a flow rate of 280μl/min. Analytes were simultaneously detected with a triple-stage quadrupole mass spectrometer (LC-MS/MS) in a selected reaction monitoring (SRM) mode with positive heated electrospray ionization (HESI) within a single 2-min run. Calibration curves were linear over a range of 50-2000 for ketamine, 10-1000 for lorazepam, 5-500 for midazolam and 1-100 for sufentanil (ng/ml). The limit of detection and the lower limit of quantification were 0.01 and 10.00 for ketamine, 0.005 and 10.00 for lorazepam, 0.018 and 5.00 for midazolam and 0.068 and 0.25 for sufentanil (ng/ml). Intra- and inter-day accuracies and precisions of all analytes were less than 15%. Bench stability with spiked serum samples was ensured after 12, 24 and 48h at room temperature, freeze- and thaw-stability after 3 cycles of thawing and freezing. The method was successfully established according to International Conference on Harmonization (ICH) guideline Q2 (R1) "Validation of Analytical Procedures" and applied in critically ill adult patients in the intensive care unit. We suggest its suitability for parallel quantification of the sedative analgesics ketamine, lorazepam, midazolam and sufentanil. The method serves as an instrumental tool for therapeutic drug monitoring (TDM) and pharmacokinetic studies [1].

[Brain death diagnosis after sedation with propofol or sufentanil. Recommendations for the usage of toxicological analytics]

BACKGROUND

Before the clinical diagnosis of brain death is made, toxicological analyses are often performed for the exclusion of effective serum levels of previously applied sedating drugs. For propofol and sufentanil there are no uniform recommendations for the usage of toxicology test results.

OBJECTIVES

To develop a standard practice in the diagnosis of brain death after therapeutic application of one of these drugs.

MATERIAL AND METHODS

Based on the current literature and the available analytical assays, an ad hoc working group consisting of specialists in toxicology and intensive care medicine compiled recommendations for the usage of toxicological analytics in the diagnosis of brain death at the Rostock University Hospital.

RESULTS

For propofol, current analytical assays allow the quantification of serum concentrations of 0.2 μg/ml and lower; the execution of clinical brain death diagnostics is recommended by the ad hoc group only at propofol serum levels lower than  0.4 μg/ml. For sufentanil, the currently prevalent assays set lower determination limits of about 0.2 ng/ml in serum and 0.1 ng/ml in urine, which is above the cautiously adopted lower therapeutic serum concentration of 0.02 ng/ml. Therefore after negative determination of sufentanil (< 0.2 ng/ml) in blood serum, the following alternative procedures are recommended: (1) the execution of clinical brain death diagnostics under administration of naloxone; or (2) at intact renal function the additional negative determination of sufentanil in urine (< 0.1 ng/ml). If an assay allowing the detection of sufentanil at ≤ 0.01 ng/ml is available, brain death diagnostics should be carried out only at a serum level lower than  0.02 ng/ml.

CONCLUSION

These recommendations may serve as a proposal for similar standards in other hospitals.

Development and validation of an ultrafiltration-UPLC-MS/MS method for rapid quantification of unbound docetaxel in human plasma

Docetaxel lipid microsphere (DT-LM) is a novel formulation of docetaxel without Tween-80. A sensitive, robust and reproducible ultrafiltration (UF) followed by UPLC-MS/MS method was developed and validated for the quantification of unbound docetaxel in human plasma using paclitaxel as IS. Ultrafiltrate samples were chromatographed on Acquity UPLC BEH C18 column (50 mm × 2.1 mm, 1.7 μm). The mobile phase was a mixture of 10mM ammonium formate in water containing 0.2% formic acid (A) and acetonitrile containing 0.2% formic acid (B). The volume of plasma utilized was only 450 μL. The calibration curve was linear over the range of 0.2-200 ng/mL, with LLOQ of 0.2 ng/mL. The method was shown to be reliable and reproducible with intra- and inter-day precision and accuracy <±15%, and extraction recovery of 98.1-104.8%. Docetaxel was stable during stability studies, e.g., short term, post-preparation and freeze-thaw cycles. The validated method was utilized to support the pharmacological study of DT-LM in patients with advanced cancer.

Influence of intensive care treatment on the protein binding of sufentanil and hydromorphone during pain therapy in postoperative cardiac surgery patients

BACKGROUND

Our objective was to evaluate the effect of intensive care treatment on the protein binding of sufentanil and hydromorphone in cardiac surgery patients during postoperative analgesia using a target-controlled infusion (TCI) and patient-controlled analgesia (PCA).

METHODS

Fifty adult patients were enrolled in this prospective randomized study; of which, 49 completed the study (age range 40-81 yr). Sufentanil was administered as an analgesic intraoperatively, and hydromorphone was dosed after operation with TCI and PCA until 8 a.m. on the first postoperative day. Arterial plasma samples were collected for drug and protein concentration measurements up to 24 h after cardiac surgery. Corresponding patient data were collected from the electronic patient data system. After explorative data analysis with principal component analysis, multivariate regression analysis and non-linear mixed effects modelling was used to study the effect of treatment on protein binding.

RESULTS

Data of 35 patients were analysed. The median protein binding of sufentanil and hydromorphone was 88.4% (IQ range 85.7-90.5%) and 11.6% (IQ range 9.5-14.3%), respectively. Free fraction of sufentanil increased towards the end of the study period, whereas hydromorphone free fraction remained nearly constant. The total sufentanil concentration and volume balance were identified as significant covariates for the protein binding of sufentanil. For the protein binding of hydromorphone, no significant covariate effects were found.

CONCLUSIONS

Sufentanil protein binding was significantly dependent on changes in the total drug concentration and volume balance addressing the importance of adequate dosing and fluid-guided therapy. Hydromorphone protein binding was nearly constant throughout the study period.

CLINICAL TRIAL REGISTRATION

EudraCT 2011-003648-31 and ClinicalTrials.gov: NCT01490268.

Simultaneous quantitation of 3-n-butylphthalide (NBP) and its four major metabolites in human plasma by LC-MS/MS using deuterated internal standards

3-n-Butylphthalide (NBP) is a cardiovascular drug widely used in China for the treatment of cerebral ischemic stroke. Our previous study showed that NBP underwent extensive metabolism in humans and that 10-keto-NBP (M2), 3-hydroxy-NBP (M3-1), 10-hydroxy-NBP (M3-2) and NBP-11-oic acid (M5-2) were the major circulating metabolites. A better understanding of the plasma exposures of NBP and its four major metabolites is crucial to supporting the safety evaluation, good clinic practice and discovery of new antistroke drugs. Herein, a liquid chromatography-tandem mass spectrometry method was developed and validated for the simultaneous determination of NBP, M2, M3-1, M3-2, and M5-2 in human plasma. To improve assay sensitivity and achieve simultaneous analysis, M3-1 and M5-2 were monitored in (-)ESI (electrospray) mode within the first 3.5 min and NBP, M2, and M3-2 thereafter in (+)ESI mode. Deuterated internal standards for all analytes were synthesized to compensate for the impact of matrix effects. Based on the vast differences in physicochemical properties among the five analytes and the necessary baseline separation of two isomers (i.e., M3-1 and M3-2), gradient elution comprising a mobile phase of methanol-acetonitrile-5 mM ammonium acetate was used after methanol-induced protein precipitation of plasma samples. The developed method was linear in the concentration range of 3.00-800 ng/ml for NBP and M2, and 3.00-2400 ng/ml for M3-1, M3-2, and M5-2. The lower limit of quantitation was 3.00 ng/ml for each analyte. The intra- and inter-day accuracy and precision were within acceptable limits (±15%) at all concentrations. The method was successfully applied to characterize the pharmacokinetic profiles of NBP and its major metabolites following a single oral administration of 200mg NBP to healthy volunteers.