Quantification of levetiracetam in plasma of neonates by ultra performance liquid chromatography–tandem mass spectrometry

Application of Physiologically Based Pharmacokinetic Modeling to Characterize the Effects of Age and Obesity on the Disposition of Levetiracetam in the Pediatric Population

BACKGROUND

Levetiracetam is an antiseizure medication used for several seizure types in adults and children aged 1 month and older; however, due to a lack of data, pharmacokinetic (PK) variability of levetiracetam is not adequately characterized in certain populations, particularly neonates, children younger than 2 years of age, and children older than 2 years of age with obesity.

OBJECTIVE

This study aimed to address the gap by leveraging PK data from two prospective standard-of-care pediatric trials (n = 88) covering an age range from 1 month to 19 years, including those with obesity (64%), and applying a physiologically based PK (PBPK) modeling framework.

METHODS

A published PBPK model of levetiracetam for children aged 2 years and older was extended to pediatric patients younger than 2 years of age and patients older than 2 years of age with obesity by accounting for the obesity and age-related changes in PK using PK-Sim® software. The prospective pediatric data, along with the literature data for neonates and children younger than 2 years of age, were used to evaluate the extended PBPK models.

RESULTS

Overall, 82.4% of data fell within the 90% interval of model-predicted concentrations, with an average fold error within twofold of the accepted criteria. PBPK modeling revealed that children with obesity had lower weight-normalized clearances (0.053 L/h/kg) on average than children without obesity (0.063 L/h/kg). The effect of maturation was well-characterized, resulting in comparable PBPK-simulated, weight-normalized clearances for neonates and children younger than 2 years of age reported from the literature.

CONCLUSIONS

PBPK modeling simulations revealed that the current US FDA-labeled pediatric dosing regimen listed in the prescribing information can produce the required exposure of levetiracetam in these target populations with dose adjustments for children with obesity aged 4 years to younger than 16 years.

Quantification of levetiracetam in plasma and urine and its application to a pharmacokinetic study of traumatic brain injury patients

Background: Levetiracetam is an antiepileptic drug used to prevent or treat seizure in patients with severe traumatic brain injury. This study aimed to develop and validate methodology suitable for measuring levetiracetam concentrations in human plasma and urine. Methods: Plasma or urine (10 μl) samples were spiked with [²H₆]-levetiracetam and processed using an acetonitrile precipitation. ESI-LC-MS/MS was employed for analyte detection. Results: The levetiracetam calibration was linear from 0.1 to 50 mg/l in a combined matrix of plasma and urine. Intra- and inter-assay imprecision and accuracy in plasma were <7.7 and 109%, and in urine were <7.9 and 108%, respectively. Conclusion: The validated method was applied to a pharmacokinetic study of levetiracetam in critically ill patients with severe traumatic brain injury.

Emerging role of clinical mass spectrometry in pathology

Mass spectrometry-based assays have been increasingly implemented in various disciplines in clinical diagnostic laboratories for their combined advantages in multiplexing capacity and high analytical specificity and sensitivity. It is now routinely used in areas including reference methods development, therapeutic drug monitoring, toxicology, endocrinology, paediatrics, immunology and microbiology to identify and quantify biomolecules in a variety of biological specimens. As new ionisation methods, instrumentation and techniques are continuously being improved and developed, novel mass spectrometry-based clinical applications will emerge for areas such as proteomics, metabolomics, haematology and anatomical pathology. This review will summarise the general principles of mass spectrometry and specifically highlight current and future clinical applications in anatomical pathology.

Levetiracetam

A comprehensive profile of levetiracetam is presented in this chapter which includes its description, formula, elemental analysis, appearance, uses and applications. Different earlier studies included for example methods of synthesis are described with its typical structural schemes. The profile also listed the drug's physical characteristics indicating its solubility, X-ray powder diffraction pattern, thermal methods of analysis as well as its spectroscopic characteristics. Different methods of analysis which includes compendial method of analysis, as well as reported method of analysis which include spectrophotometry, spectrofluorometry, electrochemical method, chromatographic method, and immunoassay method of analysis. The study was include drug stability, clinical pharmacology, e.g., mechanism of action, pharmacokinetic study. Around 70 references are recorded as a proof of this chapter.

Pharmacokinetic and Pharmacodynamic Evaluation of Intravenous Levetiracetam in Children With Epilepsy

This study aimed to evaluate the safety and tolerability of intravenous (IV) levetiracetam (LEV) as a monotherapy in children aged 1 month-16 years and to explore the pharmacokinetics (PK) of IV LEV and the time to seizure after IV then oral administration of LEV in pediatric children with epilepsy. Children diagnosed with acute unprovoked seizures requiring in-hospital IV LEV administration were included. After administration, the clinical seizure outcomes, side effects, and the Korean-Child Behavior Checklist were monitored and the PK and repeated time to seizure were analyzed via modeling using NONMEM software. Overall, 37 children with epilepsy were enrolled and underwent a PK analysis (median age, 4.6 years; median weight, 18.0 kg). Nine children (24.3%) had seizure recurrence during the follow-up period (median, 3.8 months) and 5 children (13.5%) experienced LEV-associated adverse events such as irritability (n = 2; 5.4%) and somnolence (n = 3; 8.1%). The plasma LEV concentrations after IV LEV were best described by a one-compartment linear PK model. Only body weight was associated with both the clearance and volume of distribution of LEV. The Weibull distribution model described the time to seizure recurrence well; no statistically significant predictor for the time to seizure was identified. Therefore, IV LEV was a well-tolerated and effective alternative in children with acute unprovoked seizures, and models for the PK and time to repeated seizure recurrence after LEV were successfully developed. In particular, the current use of a weight-based IV LEV dosing regimen in pediatric children is practical.

Multivariate optimization of mebeverine analysis using molecularly imprinted polymer electrochemical sensor based on silver nanoparticles

Thin film of a moleculary imprinted polymer (MIP) based on electropolymerization method with sensitive and selective binding sites for mebeverine (MEB) was developed. This film was cast on pencil graphite electrode (PGE) by electrochemical polymerization in solution of pyrrole (PY) and template MEB via cyclic voltammetry scans and further electrodeposition of silver nanoparticles (AgNPs). Several parameters controlling the performance of the silver nano particles MIP pencil graphite electrode (AgNPs-MIP-PGE) including concentration of PY(mM) concentration of mebeverine (mM), number of cycles in electropolymerization, scan rate of CV process (mV. s⁻¹), deposition time of AgNPs on to the MIP surface (s), stirring rate of loading solution (rpm), electrode loading time (min), pH of Britton–Robinson Buffer (BRB) solution were examined and optimized using multivariate optimization methods such as Plackett–Burman design (PBD) and central composite design (CCD). Two dynamic linear ranges of concentration for the MIP sensor were obtained as. 1 × 10⁻⁸ to 1 × 10⁻⁶ and 1 × 10⁻⁵ to 1 × 10⁻³ M with the limit of detection (LOD) of 8.6 × 10⁻⁹ M (S/N = 3). The proposed method was successfully intended for the determination of MEB in real samples (serum, capsule). The sensor was showed highly reproducible response (RSD 1.1%) to MEB concentration.

Rapid and simultaneous quantification of levetiracetam and its carboxylic metabolite in human plasma by liquid chromatography tandem mass spectrometry

A simple liquid chromatography tandem mass spectrometry method was developed and validated according to the guidelines of the US Food and Drug Administration and the European Medicines Agency for a simultaneous quantification of levetiracetam (LEV) and its metabolite, UCB L057 in the plasma of patients. A 0.050 mL plasma sample was prepared by a simple and direct protein precipitation with 0.450 mL acetonitrile (ACN) containing 1 µg/mL of internal standard (IS, diphenhydramine), then vortex mixed and centrifuged. A 0.100 mL of the clear supernatant was diluted with 0.400 mL water and well mixed. A 0.010 mL of the resultant solution was injected into an Agilent Zorbax SB-C18 (2.1 mm×100 mm, 3.5 µm) column with an isocratic elution at 0.5 mL/min using a mixture of 0.1% formic acid in water and ACN (40:60 v/v). Detection was performed using an AB Sciex API 3000 triple quadrupole mass spectrometer, equipped with a Turbo Ion Spray source, operating in a positive mode: LEV at transition 171.1>154.1, UCB L057 at 172.5>126.1, and IS at 256.3>167.3; with an assay run time of 2 minutes. The lower limit of quantification (LLOQ) for both LEV and UCB L057 was validated at 0.5 µg/mL, while their lower limit of detection (LOD) was 0.25 µg/mL. The calibration curves were linear between 0.5 and 100 µg/mL for both analytes. The inaccuracy and imprecision of both intra-assay and inter-assay were less than 10%. Matrix effects were consistent between sources of plasma and the recoveries of all compounds were between 100% and 110%. Stability was established under various storage and processing conditions. The carryovers from both LEV and UCB L057 were less than 6% of the LLOQ and 0.13% of the IS. This assay method has been successfully applied to a population pharmacokinetic study of LEV in patients with epilepsy.

Liquid chromatography tandem mass spectrometry in the clinical laboratory

Clinical laboratory medicine has seen the introduction and evolution of liquid chromatography tandem mass spectrometry in routine clinical laboratories over the last 10–15 years. There still exists a wide diversity of assays from very esoteric and highly specialist manual assays to more simplified kit-based assays. The technology is not static as manufacturers are continually making improvements. Mass spectrometry is now commonly used in several areas of diagnostics including therapeutic drug monitoring, toxicology, endocrinology, paediatrics and microbiology. Some of the most high throughput analyses or common analytes include vitamin D, immunosuppressant monitoring, androgen measurement and newborn screening. It also offers flexibility for the measurement of analytes in a variety of different matrices which would prove difficult with immunoassays. Unlike immunoassays or high-pressure liquid chromatography assays using ultraviolet or fluorescence detection, mass spectrometry offers better specificity and reduced interferences if attention is paid to potential isobaric compounds. Furthermore, multiplexing, which enables multiple analytes to be measured with the same volume of serum is advantageous, and the requirement for large sample volumes is decreasing as instrument sensitivity increases. There are many emerging applications in the literature. Using mass spectrometry to identify novel isoforms or modified peptides is possible as is quantification of proteins and peptides, with or without protein digests. Future developments by the manufacturers may also include mechanisms to improve the throughput of samples and strategies to decrease the level of skill required by the operators.

Precursor ion scan driven fast untargeted screening and semi-determination of caffeoylquinic acid derivatives in Cynara scolymus L

A precursor ion scan (PIS) technique based strategy was developed for rapid screening and semi-determination of caffeoylquinic acid derivatives (CADs) in artichoke (Cynara scolymus L.) using ultra-performance liquid chromatography (UPLC) coupled with tandem mass spectrometry. 1,5-Dicaffeoylquinic acid and 5-caffeoylquinic acid were used for studying the fragmentation behaviour of two classes of CADs, setting m/z 191 as a diagnostic moiety. When it was applied to artichoke sample, ten CADs were detected and elucidated in a single PIS run. Furthermore, method validation was implemented including: specificity (no interference), linearity (≥0.9993), limit of detection (LOD<0.12 ng mL(-1)) and limit of quantification (LOQ<0.25 ng mL(-1)), precision (RSD≤3.6), recovery (91.4-95.9%) and stability (at least 12 h). This approach was proven to be a powerful, selective and sensitive tool for rapid screening and semi-determination of untargeted components in natural products.

A simple assay for determination of levetiracetam in rat dried blood spots by LC-MS/MS

BACKGROUND

A simple LC-MS/MS method was developed and validated for the quantification of levetiracetam (LEV, Keppra®), a broad-spectrum antiepileptic drug (AED) in rat dried blood spots (DBS). LEV was simply extracted with methanol spiked with adenosine (ADE) as IS before LC-MS/MS analysis. The correlation between the DBS and plasma concentrations of LEV was also determined.

RESULTS

Linearity was from 0.067-60 µg/ml for LEV in DBS samples. The intra- and inter-day accuracy and precision of the assay met validation acceptance criteria. The developed assay was applied to monitor levetiracetam DBS levels in Sprague-Dawley rats after intravenous administration. DBS concentrations were well correlated to the plasma concentrations (R² = 0.9399), as fraction of LEV bound to blood cells remains very constant (0.466 ± 0.041) over a wide concentration range.

CONCLUSION

The study illustrated that DBS could be used as alternative matrix for monitoring LEV in preclinical studies.

Graphene based pipette tip solid phase extraction of marine toxins in shellfish muscle followed by UPLC-MS/MS analysis

Graphene is a novel carbonic material with great potentials for the use as sorbent due to its ultrahigh surface area. Herein, we report the use of graphene as sorbent in solid-phase extraction (SPE) using pipette tip as cartridge namely GPT-SPE, together with ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS), for the analysis of lipophilic marine toxins (LMTs), including yessotoxins (YTX), okadaic acid (OA), dinophysistoxin-1 (DTX1), gymnodimine (GYM), spirolides-1 (SPX1), pectenotoxin-2 (PTX2) and azaspiracid-1 (AZA1) in shellfish. The GPT-SPE procedure was optimized and the performance of graphene was fully validated. Results with high-sensitivity and good reproducibility was obtained and compared with that of other sorbents like C18 silica, multi-walled carbon nanotubes (MWCNTs), commercial Oasis HLB, and Strata-X for the extraction of LMTs, which showed superiority and advantages of graphene, such as good recoveries, stability and compatibility with various solvents. In order to exhibit the potentials of graphene as an excellent sorbent material, 67 mussel samples from six coastal cities of China were analyzed. OA was found to be the dominant contaminant, while YTX was also detected with low level.

A systematic review of the pharmacokinetics of antiepileptic drugs in neonates with refractory seizures

BACKGROUND

Neonatal seizures are associated with neurological sequelae and an increased risk of epilepsy later in life. Phenobarbital and phenytoin remain the antiepileptic drugs (AEDs) most commonly used to treat neonatal seizures, despite their suboptimal effectiveness and safety. As a result, other AEDs, such as levetiracetam and topiramate, are often used in neonates with refractory seizures, despite limited data and off-label use.

OBJECTIVES

To systematically review published pharmacokinetic data for second-line AEDs used in neonates with seizures and to provide dosing recommendations for these agents in the neonatal population.

METHODS

A literature search was conducted in PubMed (1949-May 2012), Medline (1950-May 2012), and Embase (1980-May 2012). Each study was ranked according to the quality of evidence it provided, based on the classification system developed by the US Preventive Services Task Force. Information extracted from each study included study design, number of subjects, gestational and postnatal age, AED dosage regimen, pharmacokinetic parameters, pharmacokinetic model, AED serum concentrations, and sampling times.

RESULTS

Nineteen relevant pharmacokinetic studies involving a total of 8 different drugs were identified. No prospective, randomized, controlled studies (level I evidence) or nonrandomized controlled studies (level II-I evidence) were identified; 2 studies were prospective, nonrandomized, uncontrolled (cohort) studies (level II-2 evidence), 11 studies obtained evidence from multiple time series (level II-3 evidence), and 6 studies were case reports or descriptive studies (level III evidence).

CONCLUSIONS

There are limited pharmacokinetic data for the use of carbamazepine, levetiracetam, lidocaine, paraldehyde, topiramate, valproic acid, and vigabatrin for neonates with seizures refractory to treatment with first-line antiepileptic agents. Further research is needed to elucidate target AED serum concentrations (if any) required to optimize effectiveness and minimize dose-related adverse effects in neonates.

Simultaneous quantification of levetiracetam and gabapentin in plasma by ultra-pressure liquid chromatography coupled with tandem mass spectrometry detection

INTRODUCTION

Gabapentin (Neurontin) and levetiracetam (Keppra) are anticonvulsants with novel structures and suggested therapeutic ranges of 2-10 mg/L and 6-20 mg/L, respectively. Gabapentin is also used extensively to manage neuropathic pain, and for this indication, wherein higher doses are prescribed, plasma concentrations of 15-30 mg/L are typical.

OBJECTIVE

Here, we describe a simple rapid assay to support therapeutic drug monitoring of gabapentin and levetiracetam in plasma by ultra-pressure liquid chromatography couples to tandem mass spectrometry (UPLC-MS/MS) detection.

METHODS

After the addition of internal standard and protein precipitation of patient plasma with methanol:acetonitrile in a 50:50 ratio, 1 μL of supernatant sample is injected onto an Acquity UPLC HSS T3, 1.8 μm, 2.1 × 50 mm (Waters) column. Elution occurs using a linear gradient of acetonitrile and water, each having 0.1% formic acid added. The column is eluted into a Waters Acquity UPLC TQD, operating in a positive mode to detect gabapentin at transition 172.18 > 154.11, levetiracetam at 171.11 > 126, and internal standard (3-amino-2-naphthoic acid) at 188.06 > 170. Secondary transitions for each analyte are also monitored for gabapentin at 172.18 > 137.06, levetiracetam at 171.11 > 154, and internal standard at 188.06 > 115. Runtime is 1.5 minutes per injection with baseline resolved chromatographic separation.

RESULTS

The analytical measurement ranges were 1-150 mg/L for gabapentin and for levetiracetam. Intra-assay imprecision by the coefficient of variance (CV) was less than 8% and interassay CV was less than 5% for both analytes, at 4 different concentrations. Results obtained from patient samples were compared with results generated by established high-performance liquid chromatography-UV methods with the following regression statistics: y = 1.12x - 0.77, r = 0.996, Sy, x = 0.89, and n = 29 for gabapentin and y = 0.991x + 0.70, r = 0.997, Sy, x = 2.24, and n = 30 for levetiracetam. No analytical interferences were identified.

CONCLUSION

: In summary, a simple reliable UPLC-MS/MS method was developed and validated for routine clinical monitoring of gabapentin and levetiracetam.

Fast liquid chromatography combined with mass spectrometry for the analysis of metabolites and proteins in human body fluids

In the last decade various analytical strategies have been established to enhance separation speed and efficiency in high performance liquid chromatography applications. Chromatographic supports based on monolithic material, small porous particles, and porous layer beads have been developed and commercialized to improve throughput and separation efficiency. This paper provides an overview of current developments in fast chromatography combined with mass spectrometry for the analysis of metabolites and proteins in clinical applications. Advances and limitations of fast chromatography for the combination with mass spectrometry are discussed. Practical aspects of, recent developments in, and the present status of high-throughput analysis of human body fluids for therapeutic drug monitoring, toxicology, clinical metabolomics, and proteomics are presented.