Measurement of Teicoplanin Concentration With Liquid Chromatography-Tandem Mass Spectrometry Method Demonstrates the Usefulness of Therapeutic Drug Monitoring in Hematologic Patient Populations

Therapeutic drug monitoring of glycopeptide antimicrobials: An overview of liquid chromatography-tandem mass spectrometry methods

Therapeutic drug monitoring (TDM) is a critical clinical tool used to optimize the safety and effectiveness of drugs by measuring their concentration in biological fluids. These fluids are primarily plasma or blood. TDM, together with real-time dosage adjustment, contributes highly to the successful management of glycopeptide antimicrobial therapies. Understanding pharmacokinetic/pharmacodynamic (PK/PD) properties is vital for optimizing antimicrobial therapies, as the efficacy of these therapies depends on both the exposure of the patient to the drug (PK) and pharmacodynamic (PD) parameters such as the in vitro estimated minimum drug concentration that inhibits bacterial growth (MIC). Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) is widely recognized as the gold standard for measuring small molecules, such as antibiotics. This review provides a comprehensive overview of LC-MS/MS methods available for TDM of glycopeptide antibiotics, including vancomycin, teicoplanin, dalbavancin, oritavancin, and telavancin.

Population pharmacokinetics and model-based dosing optimization of teicoplanin in elderly critically ill patients with pneumonia

PURPOSE

To evaluate the population pharmacokinetics and pharmacodynamics of teicoplanin in elderly critically ill patients with pneumonia for optimal dosages.

METHODS

Fifteen critically ill patients (9 men) ≥ 60 years received teicoplanin 6 mg/kg for three doses followed by standard maintenance doses (6 mg/kg q24h) with renal dosing adjustment. Serial plasma samples from all patients were analyzed simultaneously by population pharmacokinetic modeling using NONMEM. Probability of target attainment (PTA) was calculated through Monte Carlo simulations for various dosing regimens to achieve adequate systemic exposures.

RESULTS

The median (interquartile range, IQR) age, body mass index, and creatinine clearance (CrCl) was 75 (64-78) years, 22.5 (20.8-25.4) kg/m2, and 64 (47-106) mL/min, respectively. The median (IQR) peak and trough concentration was 46.5 (42.7-51.0) and 8.7 (7.2-9.5) mg/L. The population pharmacokinetic model showed slower clearance (CL) and larger peripheral volume of distribution (V2) in patients with reduced CrCl: CL (L/h) = 0.629 × (CrCl/64)0.656, V2 (L) = 55.7 × (CrCl/64)-0.665. Model-based simulations showed PTAs ≥85% only for higher-dose regimens (12 mg/kg) up to an MIC of 0.5 mg/L.

CONCLUSIONS

Standard teicoplanin dosages for pneumonia may provide inadequate systemic exposures in elderly critically ill patients. High-dose regimens should be considered as empiric therapy or for less susceptible pathogens.

Development and validation of a bioanalytical assay for the measurement of total and unbound teicoplanin in human serum

BACKGROUND

The glycopeptide teicoplanin is considered first-line treatment for severe infections caused by Gram-positive bacteria. Individualized treatment of teicoplanin is gaining interest. As only protein-unbound drug is pharmacologically active, a sensitive assay measuring unbound and total teicoplanin is indispensable for pharmacological research and dose optimization.

OBJECTIVES

To develop and validate a UPLC-MS/MS method to quantify unbound and total teicoplanin in human serum.

METHODS

The developed assay was validated according to the ICH guideline M10 on Bioanalytical Method Validation and study sample analysis. Unbound teicoplanin was obtained by ultrafiltration. The assay was cross-validated with a quantitative microsphere (QMS) immunoassay in a side-by-side comparison using 40 patient samples.

RESULTS

With the developed and validated method, all main teicoplanin components (A2-1, A2-2/A2-3, A2-4/A2-5 and A3-1) can be quantified. Total run time was 5.5 min. Concentration range was 2.5-150 mg/L for total and 0.1-25 mg/L for unbound teicoplanin. Precision (coefficient of variation) and accuracy (bias) of total teicoplanin were 5.97% and 107%, respectively, and 7.17% and 108%, respectively, for unbound teicoplanin.Bland-Altman analysis showed total concentrations measured with the UPLC-MS/MS method were equivalent to the results of the QMS immunoassay. A total of 188 samples from 30 patients admitted to the ICU and haematology department were measured; total concentrations ranged between 2.92 and 98.5 mg/L, and unbound concentrations ranged between 0.37 and 30.7 mg/L.

CONCLUSIONS

The developed method provided rapid, precise and accurate measurement of unbound and total teicoplanin. The developed method is now routinely applied in pharmacological research and clinical practice.

Optimal Teicoplanin Dosage Regimens in Critically Ill Patients: Population Pharmacokinetics and Dosing Simulations Based on Renal Function and Infection Type

Purpose

To develop a population pharmacokinetic model describing teicoplanin concentrations in patients hospitalized in intensive care unit (ICU) and to perform Monte Carlo simulations to provide detailed dosing regimens of teicoplanin.

Methods

This single-center, prospective, observational study was conducted on 151 patients in ICU with 347 plasma samples. The population pharmacokinetics model was established and various covariates were evaluated. The probability of target attainment (PTA) of various proposal dosing regimens was calculated by Monte Carlo simulations.

Results

The two-compartment model adequately described teicoplanin concentration-time data. The estimated glomerular filtration rate (eGFR) associated with systemic clearance (CL) was the only covariate included in the final model. The estimate of CL was 0.838 L/h, with the eGFR adjustment factor of 0.00823. The volume of the central compartment (Vc), inter-compartmental clearance (Q) and volumes of the peripheral compartments (Vp) were 14.4 L, 3.08 L/h and 51.6 L, respectively. The simulations revealed that the standard dosage regimen was only sufficient for the patients with severe renal dysfunction (eGFR ≤ 30 mL/min/1.73 m2) to attain target trough concentration (Cmin, PTA 52.8%). When eGFR > 30 mL/min/1.73 m2, increasing dose and the administration times of loading doses were the preferred options to achieve target Cmin based on the renal function and types of infection.

Conclusion

The most commonly used standard dosage regimen was insufficient for all ICU patients. Our study provided detailed dosing regimens of teicoplanin stratified by eGFR and types of infection for ICU patients.

Identification of a frit-related sample carryover in newborn screening by tandem mass spectrometry

The need for high-throughput analysis of multiple analytes for inborn errors of metabolism in newborn screening (NBS) has led to the introduction of tandem mass spectrometry (MS/MS) into the NBS laboratory. In a flow-injection analysis (FIA), the predominant MS/MS method utilized for NBS, samples are introduced directly into the mass spectrometer without chromatographic separation. When a high-throughput FIA-based MS/MS method is implemented on newer generations of mass spectrometers with increased sensitivity, the risk of carryover and contamination increases. In the present study, we report the carryover of ornithine identified during the implementation of the NeoBase™ 2 (PerkinElmer) non-derivatized kits on the Xevo-TQD platform (Waters Corporation) and describe the source of the carryover, which was traced to the stainless-steel frit-type inline filter. Furthermore, a possible compound-dependent interaction with the stainless-steel frit is suggested based on the structure of ornithine and its effect on separation techniques. Investigation and mitigation of carryover can be a time and resource consuming process, and to this end, our report on identification of a stainless-steel frit as the source of delayed elution and carryover of ornithine should be recognized as a rare, albeit possible source of carryover in FIA-MS/MS methods adopted for NST.

Therapeutic Drug Level Monitoring of Teicoplanin in Korean Pediatric Patients with Normal versus Impaired Renal Function

BACKGROUND

Teicoplanin is used to treat serious gram-positive infections. Optimal teicoplanin trough levels are considered to be ≥ 10 μg/mL. Despite its wide use in various clinical settings, data on teicoplanin trough level in pediatric patients are limited. Therefore, the aim of this study was to investigate the therapeutic drug level monitoring of teicoplanin in Korean pediatric patients, including those with impaired renal function.

METHODS

A retrospective study was performed in pediatric patients (age ≤ 18 years old) who received teicoplanin from September 2014 to April 2018. The regimen included a loading dose of 10 mg/kg/dose at 12 hours' interval three times in a row, and a maintenance dose of 10 mg/kg/dose commenced at 24 hours of interval after the loading dose, with a maximum of 400 mg/dose, respectively. The first therapeutic drug levels were measured. Distribution and characteristics of trough levels in patients with decreased renal function and those with bacteremia were also assessed.

RESULTS

A total of 187 trough levels were collected from 143 patients. Hematologic and oncologic diseases were the most common underlying diseases (83.2%, n = 119). One hundred eighty trough levels were first measured, and their median value was 16.2 μg/mL (range, 2.3-100 μg/mL) and the median interval between initial teicoplanin injection and 1st trough level was 96.5 hours (range 47.6-179.3 hours). Lower steady-state levels were observed in younger age group (median, 13.5 vs. 18.0 μg/mL, P = 0.038). Median trough levels were higher in patients with decreased renal functions (P < 0.001). In addition, among eight with gram-positive bacteremia, seven of them had a favorable outcome.

CONCLUSION

This study provides additive information on trough level monitoring of teicoplanin in children with impaired renal function and treatment effect in patients with gram-positive bacteremia. Careful monitoring for steady state trough levels of teicoplanin is warranted.

Interlaboratory analysis of teicoplanin plasma concentration assays among Chinese laboratories

WHAT IS KNOWN AND OBJECTIVE

Teicoplanin is widely used for the treatment of infections caused by drug-resistant Gram-positive bacteria. Since there is a good correlation between trough levels and clinical outcome, therapeutic drug monitoring (TDM) is recommended to achieve better clinical curative effects. However, TDM of teicoplanin is not routine in China. So, a programme was initiated in 2017, including both HPLC method establishment and interlaboratory quality assessment, for the measurement of teicoplanin.

METHODS

A main centre and a quality control centre were set up in the study. An HPLC-based method of teicoplanin determination in plasma was developed by the main centre. Analysis was performed using a Waters Symmetry C18 column (250 mm × 4.6 mm, 5 µm). The mobile phase was NaH₂ PO₄ (0.01 mol/L) and acetonitrile (75:25 v/v; pH 3.3), with a flow rate of 1.0 mL/min and a detection wavelength of 215 nm. Piperacillin sodium was selected as an internal standard (IS). Twenty-six additional TDM centres were then recruited to adopt this method. Then, all the centres were asked to take part in a quality control assessment evaluated by the quality control centre.

RESULTS

For all TDM centres, linearity of teicoplanin concentration ranges was between 3.125 and 100 µg/mL. Intraday and interday accuracies ranged from 87.1% to 118.4%. Intraday and interday precision ranged from 0.3% to 13.8%. Therapeutic drug monitoring centres all passed inter-room quality assessment. All samples tested met the acceptance criteria. Then, 542 samples were collected. Patients with sub-optimal (≤10 mg/L) plasma teicoplanin concentrations constituted 42% of the total study population.

WHAT IS NEW AND CONCLUSIONS

For the first time, a simple, rapid and accurate HPLC method for determining teicoplanin levels was successfully applied to therapeutic drug monitoring in clinical practice for twenty-seven TDM centres in China. The results demonstrated excellent interlaboratory agreement for teicoplanin testing and provide support for clinical laboratory quality management and results inter-accreditation.

A nationwide utilization survey of therapeutic drug monitoring for five antibiotics in South Korea

Purpose

The current status of therapeutic drug monitoring (TDM) assay utilization by clinical laboratories in South Korea remains little known. We investigated the TDM status of five antibiotics known for nephrotoxicity (vancomycin, amikacin, gentamicin, tobramycin, and teicoplanin) for the improvement of TDM in South Korea among patients with infectious diseases using a cross-sectional nationwide survey.

Patients and methods

We developed an online questionnaire and collected responses using a user-friendly web-based platform. The survey included questions about laboratory characteristics, implementation and operation of drug assays, implementation and operation of TDM consulting services, patient needs, and barriers to providing better TDM service including expectations and concerns about other platform-based drug assays.

Results

Among a total of 235 clinical laboratories, 112 (47.7%) responded, and 62 of the responding laboratories (55.4%) possessed drug assay facilities. Only 41.2% to 58.1% of respondents were providing TDM consulting services for each antibiotic. Respondents indicated that there are unmet needs regarding drug assays and TDM consultation as well as barriers to TDM utilization including high operating costs, lack of knowledge about TDM, lack of user-friendly software, lack of medical and laboratory information systems that can access patient information critical for TDM dose calculation, and reimbursement issues.

Conclusion

This study, the first nationwide survey addressing these questions, showed that there are barriers against the utilization of TDM in South Korea. These barriers may be addressed by improving drug assays and TDM consulting services with the goals of new analytical method development, better interpretation of results, consultation services, and quality control.

Therapeutic drug monitoring of teicoplanin using an LC-MS/MS method: Analysis of 421 measurements in a naturalistic clinical setting

Teicoplanin is a glycopeptide antibiotic used for treatment of severe Gram-positive bacterial infection. The aim of this study was to develop and validate a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for therapeutic drug monitoring (TDM) of teicoplanin and to review our clinical experience. We established an LC-MS/MS method to analyze serum concentration of teicoplanin using simple protein precipitation with a 5 min run time for each sample. The linearity, lower limit of quantitation, detection accuracy, precision, carryover, matrix effect, and extraction recovery were evaluated. From September 2014 to June 2017, a total of 421 serum teicoplanin concentrations was measured in 223 patients. We collected demographic and clinical data, medication history, and laboratory findings through retrospective review of medical records. The LC-MS/MS method was linear for serum teicoplanin concentrations in the range of 12.0-89.0 μg/mL. The intra- and inter-assay precisions were below CV 7.5%. The accuracy was less than ±10% bias. The lower limit of quantification was 0.2 μg/mL. The extraction recovery ranged from 88.8% to 96.6%. Of 421 measurements, 87 (20.7%) were subtherapeutic (< 10 μg/mL), and four (0.9%) were above the toxic threshold (≥ 60 μg/mL). Serum teicoplanin concentration was measured once in 140 patients (63%), and multiple measurements were completed for the others (83 patients, 37%). Intra-patient variability in teicoplanin concentration was found (CV 33%, range 2-94%). Our simple and rapid LC-MS/MS method was successfully applied in TDM of teicoplanin in clinical practice. Such TDM of teicoplanin may be useful for individualized dose adjustment.