Therapeutic drug monitoring of caffeine and its primary metabolites in plasma using LC-ESI-MS/MS for apnea of prematurity treatment: Evaluation of ultrapure water as a surrogate matrix.

The growing evidence has endorsed the view that therapeutic drug monitoring of caffeine for apnea of prematurity is helpful for dose tailoring when the therapeutic response is lacking or toxicity is suspected. However, plasma without caffeine is difficult to obtain. Therefore, a method was developed and validated to measure caffeine and its three primary metabolites (paraxanthine, theobromine and theophylline) using LC-ESI-MS/MS in human plasma and several surrogate matrices. The chromatographic separation of analytes was finally achieved on a Waters Symmetry C18 (4.6 × 75 mm, 3.5 µm) column. Several strategies were successfully applied to overcome the matrix effects: (a) appropriate dilution for sample cleanup; (b) a starting lower proportion of organic phase; and (c) multiple individual stable-labeled isotopic internal standards. The parallelism between the authentic matrix and surrogate matrices was convincing. The recovery of the analytes in both human plasma and rat plasma was acceptable over the linear range (0.500-50.0 µg/ml for caffeine and 0.0100-1.00 µg/ml for three metabolites). The method was successfully applied in 118 samples from 74 preterm infants with apnea of prematurity. The rat plasma or ultrapure water as a surrogate matrix is worthy of recommendation for routine therapeutic drug monitoring of caffeine.

Severe Vincristine-Induced Neuropathic Pain: A Case Report with Pharmacogenetic Analysis and Literature Review.

Vincristine-induced peripheral neuropathy (VIPN) is a common adverse effect of vincristine (VCR) for which there is no preventative or curative treatment. Here, we report a case of a patient suffering from severe VCR-related neurotoxicity. To explore the possible causes of severe VIPN in this patient, a set of genes involved in VCR metabolism, transport or are related to the cytoskeleton, microtubules, and inherited neurological diseases gene polymorphisms were examined via pharmacogenetic analyses. The genotyping results revealed the presence of a complex pattern of polymorphisms in CYP3A5, ABCC2, SYNE2, BAHD1, NPSR1, MTNR1B, CEP72, miR-4481 and miR-3117. A comprehensive understanding of all the pharmacogenetic risk factors for VIPN may explain the occurrence of severe neurotoxicity in our patient. This case brings to light the potential importance of pharmacogenetic testing in clinical practice. It also exemplifies the importance of developing early-detection strategies to optimize treatment regimens through prior risk stratification while reducing adverse drug reactions and personalizing therapy.

Switching Between LC-ESI-MS/MS and EMIT Methods for Routine TDM of Valproic Acid in Pediatric Patients With Epilepsy: What Clinicians and Researchers Need to Know.

Background: Valproic acid (VPA) is a widely used antiseizure medication and its dosing needs to be tailored individually through therapeutic drug monitoring (TDM) to avoid or prevent toxicity. Currently, immune-enzymatic assays such as Enzyme Multiplied Immunoassay Technique (EMIT), and Liquid Chromatography (LC)-based techniques, particularly coupled to Electrospray Ionization Tandem Mass Spectrometry (LC-ESI-MS/MS), resulting a potential lack of concordance between laboratories. Methods: In this study, plasma VPA concentrations were determined for 711 pediatric patients with epilepsy by a routine EMIT assay and by a validated in-house LC-ESI-MS/MS method on the same group of samples, aimed to address the aforementioned concern. Consistency between two assays was evaluated using linear regression and Bland-Altman analysis. Results: The calibration curve was linear in the range of 5.00-300 µg/ml for LC-ESI-MS/MS method and 1.00-150 µg/ml for EMIT assay, respectively. The two methods were proven to be accurate with quality control samples. As a result, a significant correlation between two methods was obtained with a regression equation described as [ EMIT ] = 1.214 × [ LC - ESI - MS / MS ] + 3.054 (r 2 = 0.9281). Bland-Altman plot showed a mean bias of 14.5 µg/ml (95% confidence interval (CI) (-0.2, 29.2) and a mean increase of 27.8% (95% CI (3.3, 52.4) measured by EMIT assay more than that measured by LC-ESI-MS/MS method. Conclusion: In conclusion, two methods were closely correlated, but EMIT assay overestimate VPA levels in human plasma compared with LC-ESI-MS/MS method. Due to the observed significant discordance between the tested methods, switching from immunoassays to LC-based techniques for TDM of VPA deserves close attention and therapeutic range of 35.0-75.0 µg/ml may be feasible. However, further studies are needed to evaluate the eligibility of this alternative range in the clinical practice. Clinicians should be informed when switching the VPA quantitation methods during the clinical practice.

Biogenic volatile organic compounds from 14 landscape woody species: Tree species selection in the construction of urban greenspace with forest healthcare effects.

Biogenic volatile organic compound (BVOC) is an important part of forest healthcare effect, while it has not received enough attention in urban greenspace construction. Consequently, the aim of this study was to analyze BVOC emission rates and compositions released from leaves and flowers of landscape species in urban greenspace and to make suggestions for species selection and planting configuration in urban greenspace construction. BVOC emissions were collected and analyzed using dynamic flow enclosure technique with GC-MS in summer months (for leaf) and spring months (for flower) from 14 woody landscape species in northern China, which are 2 coniferous species (Pinus tabuliformis and Sabina vulgaris) and 12 broad-leaved species (Viburnum opulus, Kolkwitzia amabilis, Philadelphus pekinensis, Lonicera maackii, Cercis chinensis, Deutzia parviflora, Berberis thunbergia, Kerria japonica, Rosa xanthina, Syringa oblata, Syringa reticulata, and Cerasus serrulata). We found leaf emission rates of coniferous species were more than 20 µg∙g-1Dw∙h-1 and mainly consisted of monoterpenes, while that of sampled broad-leaved species were less than 10 µg∙g-1Dw∙h-1 and mainly consisted of fatty acid derivatives. Most broad-leaved species had relatively high emission rates of flowers, ranging from 15 to 115 µg∙g-1Dw∙h-1. Flower emissions of Syringa oblata and Syringa reticulata contained large amounts of aldehydes, and that of other broad-leaved species mainly contained terpenes, alcohols, and esters. We suggest the species with leaves that release large amounts of monoterpenes, and species with flowers that release large amounts of fragrant compounds are classified as healthcare species, while species with a dense crown and low emission rates of pungent compounds are classified as space-creation species. Based on this, planners could design urban greenspace with healthcare effects, and develop multi-functional, innovative, and sustainable urban greenspaces.

Caffeine for the Pharmacological Treatment of Apnea of Prematurity in the NICU: Dose Selection Conundrum, Therapeutic Drug Monitoring and Genetic Factors.

Caffeine citrate is the drug of choice for the pharmacological treatment of apnea of prematurity. Factors such as maturity and genetic variation contribute to the interindividual variability in the clinical response to caffeine therapy in preterm infants, making the optimal dose administered controversial. Moreover, the necessity for therapeutic drug monitoring (TDM) of caffeine is still worth discussing due to the need to achieve the desired target concentrations as well as concerns about the safety of higher doses. Therefore, we reviewed the pharmacokinetic profile of caffeine in preterm infants, evidence of the safety and efficacy of different doses of caffeine, therapeutic concentration ranges of caffeine and impact of genetic variability on caffeine therapy. Whereas the safety and efficacy of standard-dose caffeine have been demonstrated, evidence for the safety of higher administered doses is insufficient. Thus, preterm infants who lack clinical response to standard-dose caffeine therapy are of interest for TDM when dose optimization is performed. Polymorphisms in pharmacodynamics-related genes, but not in pharmacokinetics-related genes, have a significant impact on the interindividual variability in clinical response to caffeine therapy. For preterm infants lacking clinical response, how to develop individualized medication regimens for caffeine remains to be explored.

Determination of atomoxetine levels in human plasma using LC-MS/MS and clinical application to Chinese children with ADHD based on CPIC guidelines.

The Clinical Pharmacogenetic Implementation Consortium (CPIC) guidelines for personalized atomoxetine therapy are based on the CYP2D6 genotype information and the peak plasma concentrations of atomoxetine. Therefore, a highly rapid, sensitive, and reproducible method is critical for the clinical implementation of the guidelines. In this study, an LC-MS/MS approach was developed and validated for the determination of atomoxetine levels in human plasma using atomoxetine-d3 as the internal standard. Samples were prepared by simple protein precipitation method with MeOH. The analyte was separated using a Kinetex C18 column (2.1 mm × 50 mm, 2.6 µm, Phenomenex) with a flow rate of 0.25 mL min-1, using a gradient elution. A MeOH and water solution containing 5 mM ammonium acetate and 0.1 mM formic acid (pH 6.26) was used as the mobile phase and successfully solved the problem of inconsistent retention time between the plasma samples and the solution samples of atomoxetine. Detection was performed under positive-electrospray-ion multiple reaction-monitoring mode using the 256.4 → 43.8 and 259.3 → 47.0 transitions for atomoxetine and atomoxetine-d3, respectively. Linearity was achieved using an extremely wide range, from 0.500 to 2000 ng mL-1 in plasma. The intra- and inter-batch precision and accuracy, dilution accuracy, recovery, and stability of the method were all within the acceptable limits and no matrix effect was observed. With a complex needle wash solution containing ACN : MeOH : isopropanol : H2O (4 : 4:1 : 1, v/v/v/v), carryover contamination was eliminated successfully. This method was successfully implemented on pediatric patients with attention-deficit/hyperactivity disorder and provided valuable information to enable clinicians to do dose selection and titration.

Caffeine Therapy for Apnea of Prematurity: Role of the Circadian CLOCK Gene Polymorphism.

Standard-dose caffeine citrate has been routinely prescribed for apnea of prematurity (AOP) management; however, some preterm infants respond well to the therapy while others do not. The AOP phenotype has been attributed solely to the immature control of the respiratory system consequent to preterm birth, but there are also important genetic influences. Based on our previous report, we tested the hypothesis that the human circadian locomotor output cycles kaput (CLOCK) gene polymorphisms play a role in the response to caffeine citrate therapy in preterm infants. We also studied the interactions of the circadian clock with aryl hydrocarbon receptor (AHR) signaling pathways in preterm babies who received caffeine citrate. This single-center study collected data from 112 preterm infants (<35 weeks gestational age) between July 2017 and July 2018, including apnea-free (n = 48) and apneic (n = 64) groups. Eighty-eight candidate single nucleotide polymorphisms (SNPs) were tested using the MassARRAY system. Association analysis was performed using the PLINK Whole Genome Data Analysis Toolset and SNPStats software. Linkage disequilibrium (LD) and haplotype analyses were performed using Hapview software. No significant intergroup differences in allele distributions or genotype frequencies of CYP1A2, CYP3A4, CYP3A5, and CYP3A7 were detected in our study on preterm babies. Two more SNPs in AHR were found to be associated with determining the response to caffeine citrate therapy in our pediatric patients. Of the 46 candidate SNPs in the CLOCK gene, 26 were found to be associated with determining the response to caffeine treatment in these babies. Interestingly, a significant association was retained for 18 SNPs in the CLOCK gene after false discovery rate correction. Moreover, strong LD formed in those variants in AHR, ADORA2A, and CLOCK genes was confirmed to be significantly associated with a better response to standard-dose caffeine therapy. In summary, CLOCK gene polymorphisms play a role in determining the response to caffeine therapy in premature neonates with AOP. However, whether the AHR and CLOCK signaling pathways crosstalk with each other during caffeine treatment remains largely unclear. Future clinical studies including more immature babies and basic research are needed to explore the mechanism by which circadian rhythms affect the response to caffeine therapy.