Liquid chromatography-tandem mass spectrometry for determination of fingolimod and its active metabolite fingolimod phosphate in whole blood of patients with multiple sclerosis.

Fingolimod is an oral drug for the escalation of treatment of relapsing-remitting multiple sclerosis in patients with persistent disease activity on first-line drugs or in patients with rapidly progressive severe relapsing-remitting multiple sclerosis. An ultra-high-performance liquid chromatography-tandem mass spectrometry method for determining the concentrations of fingolimod and its active metabolite fingolimod phosphate in whole blood has been developed and validated. The advantages of this method are the easy, fast and cheap sample preparation using protein precipitation from blood with a mixture of acetonitrile-methanol (40:60, v/v). Chromatographic separation was performed on a ultra-high performance liquid chromatography BEH C18 1.7 µm (100 × 2.1 mm) column. Two modes of ionization, electrospray ionization and atmospheric pressure chemical ionization, were tested and compared. For validation, the electrospray ionization mode was chosen. As internal standard, isotopically labeled fingolimod-D4 was used to quantify the analytes. The method was validated according to the rules of the European Medicines Agency. The coefficients of variation for fingolimod were in the range of 1.13-11.88%, and the recovery was 98.80-106.00%. The coefficients of variation for fingolimod phosphate were in the range of 2.73-9.31%, and the recovery was 90.08-107.00%. The method is quite easy and fast and can be used for routine analysis.

Was it necessary to change the therapeutic range of topiramate?

AIMS: The Norwegian Association for Clinical Pharmacology in their National Guidelines decreased the therapeutic range (TR) of topiramate (TPM) from 5-20 mg/L to 2-10 mg/L. The objective of this study is to ascertain which TR produces better clinical outcomes. METHODS: The data sources were request forms for routine therapeutic drug monitoring (TDM) of TPM. Concentration dependent adverse drug reactions (ADRs) were evaluated in 1721 samples taken pre-dose. Seizure frequency analysis was performed in 294 samples of monotherapy. Statistical analysis was performed using Prism 5.0, GraphPad Instatt: One-way ANOVA with Bonferroni correction for median plasma level (PL) and χ2 -test with Bonferroni correction for seizure frequency and for distribution of PL according to TR 5-20 mg/L and intervals <2, 2-5, 5-10, 10-20, >20 mg/L. RESULTS: Better seizure control was found in children both in the whole cohort (without seizure 49% vs 37% adults), as well as in monotherapy (56% vs 44%), in children with PL 5-20 mg/L vs <5 mg/L (65% vs 44%) and in children with PL 5-10 mg/L vs <2 mg/L (63 vs 14%). PL in seizure-free patients did not differ from those with seizure. Seizure control was poorer in the period 2003-2005 compared to 2006-2011. ADRs reported in 38 samples (2.8%) were not related to PL. CONCLUSIONS: Change of TR is not recommended.

Comparison of Mw\Pharm 3.30 and Mw\Pharm ++ (Windows version) software for PK/PD monitoring of vancomycin: A priori modeling.

OBJECTIVE: To evaluate the possibility of population-based dose optimization with the aid of MwPharm modeling and to find the best model in the Windows version (WIN). MATERIALS: 25 patients repeatedly examined for vancomycin (mean age 63 ± 14 years, body weight 88 ± 21 kg, median dose 1 g/12 h). METHODS: Trough concentrations predicted by WIN models "vancomycin_adult_k_C2", "#vancomycin_adult_C2", "vancomycin_adult_C2", and "vancomycin adult" DOS model (DOS) were compared with the measured value. STATISTICS: The percentage prediction error (%PE) calculated as (predicted - measured)/measured values, Blandt-Altman plot, root mean square error (RMSE), Pearson's coefficient of rank correlation (R). Data is presented as mean ± SD. Student's t-test was used for prediction precision evaluation. RESULTS: The %PE varied from +44.4 ± 65.2% to +76.5 ± 84.3%, p < 0.001. "#vancomycin_adult_C2" model produced the lowest %PE among WIN models as well as the lowest RMSE (79) and Blandt-Altman bias (-4.01 ± 7.59), but the Pearson's correlation (0.6843, p = 0.0002) was less tight. DOS model produced the second lowest RMSE (81), %PE (+45.9 ± 66.6%), and Blandt-Altman bias (-4.83 ± 6.97) and highest Pearson's R (0.7847, p < 0.0001). "vancomycin_adult_C2" produced the third best prediction: RMSE (113), %PE (62.8 ± 92.6%), Blandt-Altman bias (-6.78 ± 11.2) but Pearson's R was the poorest (0.5773, p = 0.0025). CONCLUSION: The lowest %PE and highest Pearson's R were achieved by the "#vancomycin_adult_C2" model. Due to the poor predictive performance of all MwPharm versions and models, we find all of them unsuitable for a priori vancomycin dosing management. Other software should be evaluated for routine use.

Expression and 7-day time course of circulating microRNAs in septic patients treated with nephrotoxic antibiotic agents.

BACKGROUND: Through regulation of signaling pathways, microRNAs (miRNAs) can be involved in sepsis and associated organ dysfunction. The aims of this study were to track the 7-day time course of blood miRNAs in patients with sepsis treated with vancomycin, gentamicin, or a non-nephrotoxic antibiotic and miRNA associations with neutrophil gelatinase-associated lipokalin (NGAL), creatinine, procalcitonin, interleukin-6, and acute kidney injury (AKI) stage. METHODS: Of 46 adult patients, 7 were on vancomycin, 20 on gentamicin, and 19 on another antibiotic. Blood samples were collected on days 1, 4, and 7 of treatment, and miRNAs were identified using quantitative reverse transcription PCR. RESULTS: The results showed no relationship between miRNA levels and biochemical variables on day 1. By day 7 of gentamicin treatment miR-15a-5p provided good discrimination between AKI and non-AKI (area under curve, 0.828). In patients taking vancomycin, miR-155-5p and miR-192-5p positively correlated with creatinine and NGAL values, and miR-192-5p and miR-423-5p positively correlated with procalcitonin and interleukin-6 in patients treated with a non-nephrotoxic antibiotic. In patients together we found positive correlation between miR-155-5p and miR-423-5p and all biochemical markers. CONCLUSION: The results suggest that these four miRNAs may serve as diagnostic or therapeutic tool in sepsis, renal injury and nephrotoxic treatment. TRIAL REGISTRATION: ClinicalTrials.gov , ID: NCT04991376 . Registered on 27 July 2021.

Determination of acyclovir and its metabolite 9-carboxymethoxymethylguanide in human serum by ultra-high-performance liquid chromatography-tandem mass spectrometry.

A simple and rapid ultra-high-performance liquid chromatography coupled with mass spectrometry method was developed for acyclovir and its metabolite 9-carboxymethoxymethylguanine in human serum. After precipitation of serum samples with 0.1% formic acid in acetonitrile/methanol (40:60, v/v), components were separated on a Luna Omega C18 column (1.6 µm; 2.1 × 150 mm) at 40°C. Mobile phase A (2 mmol/L ammonium acetate, 0.1% formic acid in 5% acetonitrile, v/v/v) and mobile phase B (2 mmol/L ammonium acetate, 0.1% formic acid in 95% acetonitrile, v/v/v) were used for gradient elution. A linear calibration curve was obtained over the range of 0.05-50 mg/L, and the correlation coefficients were better than 0.999. The limit of quantitation was 0.05 mg/L for both analytes. The intra- and interday accuracy and precision at three concentration levels ranged between 1.6 and 13.3%, and recoveries were achieved with a range between 92.2 and 114.2%. This method was developed and validated for the therapeutic monitoring of acyclovir in patients.

Therapeutic monitoring of amiodarone and desethylamiodarone after surgical ablation of atrial fibrillation-evaluation of the relationship between clinical effect and the serum concentration.

BACKGROUND: Association between clinical effect and serum concentration of amiodarone (AMI) and its active metabolite desethylamidarone (DEA) in patients after surgical ablation (SA) of atrial fibrillation (AF) has not yet been studied. AIMS: We wanted to find a correlation between AMI and DEA serum concentration and maintaining sinus rhythm (SR) after SA of AF. METHODS: Sixty eight patients with AF who had undergone surgical ablation between 2014 and 2017 were included in a single-centre, prospective, observational study. Maintaining of SR was evaluated by standard 12-lead ECG and 24-hour Holter ECG monitoring at months 1, 3, 6 and 12 following surgery. Therapeutic monitoring of AMI and DEA concentrations was done to optimize therapy and adverse effects were followed up. RESULTS: We have noticed a high success rate in maintaining of SR (overall 83%). The median of serum concentration of AMI was 0.81 mg/L (range 0.16-2.35 mg/L) and DEA 0.70 mg/l (range 0.19-2.63 mg/L). No significant differences were found in the serum concentratration of AMI, DEA or DEA/AMI concentratration ratios between patients with SR and persistent supraventricular tachyarrhythmia except on the second outpatient visit. We observed significant correlation between serum concentration of DEA and thyroid-stimulating hormone elevation. CONCLUSION: We confirmed the efficacy of AMI and DEA at the measured serum concentrations. However, analysis of these concentrations alone cannot replace assessment of the clinical response for treatment. Establishment of individual AMI (and DEA) concentrations at which the optimal therapeutic response is achieved seems to be advantageous. Therapeutic monitoring of AMI and DEA is helpful in personalised pharmacotherapy after SA of AF.

Acute Kidney Injury in Septic Patients Treated by Selected Nephrotoxic Antibiotic Agents-Pathophysiology and Biomarkers-A Review.

Acute kidney injury is a common complication in critically ill patients with sepsis and/or septic shock. Further, some essential antimicrobial treatment drugs are themselves nephrotoxic. For this reason, timely diagnosis and adequate therapeutic management are paramount. Of potential acute kidney injury (AKI) biomarkers, non-protein-coding RNAs are a subject of ongoing research. This review covers the pathophysiology of vancomycin and gentamicin nephrotoxicity in particular, septic AKI and the microRNAs involved in the pathophysiology of both syndromes. PubMED, UptoDate, MEDLINE and Cochrane databases were searched, using the terms: biomarkers, acute kidney injury, antibiotic nephrotoxicity, sepsis, miRNA and nephrotoxicity. A comprehensive review describing pathophysiology and potential biomarkers of septic and toxic acute kidney injury in septic patients was conducted. In addition, five miRNAs: miR-15a-5p, miR-192-5p, miR-155-5p, miR-486-5p and miR-423-5p specific to septic and toxic acute kidney injury in septic patients, treated by nephrotoxic antibiotic agents (vancomycin and gentamicin) were identified. However, while these are at the stage of clinical testing, preclinical and clinical trials are needed before they can be considered useful biomarkers or therapeutic targets of AKI in the context of antibiotic nephrotoxicity or septic injury.

Meropenem serum concentrations in intensive care patients: a retrospective analysis.

OBJECTIVES: To determine whether currently used meropenem dosages in our hospital provide adequate serum concentrations. METHODS: Trough blood samples taken during the first meropenem concentration monitoring were included. For the evaluation of achievement of the pharmacokinetic/pharmacodynamic (PK/PD) target, MIC of the pathogens defined by the European Committee on Antimicrobial Susceptibility testing was selected. RESULTS: Eighty three patients were enrolled. A large variability in meropenem trough serum concentrations was observed (median 34.3 mg/L, range < 1.0-146.1 mg/L). The lowest PK/PD target for susceptible pathogens (100% T > MIC) was achieved in 100% of patients on dialysis and continuous renal replacement therapy (CRRT) and in 91% non-RRT patients. For pathogens with intermediate susceptibility, 100% T > MIC was attained in all patients on CRRT and 96% on dialysis, only 74% non-RRT patients achieved this PK/PD target. Patients on RRT were more likely to achieve the highest PK/PD target 100% T > 5 × MIC, P < 0.05. Higher proportion of patients on RRT would also require meropenem dose reduction if upper limit 100% T > 10 × MIC was chosen, P < 0.05. CONCLUSIONS: Administration of a standard meropenem dose to critically ill patients leads to a large concentration variability. Thus, a personalised dosing regimen is crucial for the achievement of adequate meropenem exposure.

A Short Communication: Lamotrigine Levels in Milk, Mothers, and Breastfed Infants During the First Postnatal Month.

BACKGROUND: Lamotrigine has become the most frequently prescribed drug in the treatment of pregnant women with epilepsy. Although some relevant studies have found a wide milk/maternal serum as well as infant/maternal serum concentration ratio, different infant ages at the time of sampling and small number of patients preclude comparison. The aim of this study was to provide a consistent evaluation. METHODS: Data of 43 nursing women treated by lamotrigine were evaluated retrospectively. The authors followed the transport of lamotrigine during the first postnatal month from mothers to breastfed infants through maternal milk between the years 2002 and 2017. RESULTS: Lamotrigine concentrations varied from 1.1 to 14.9 mg/L in the maternal serum, from <0.66 to 9.1 mg/L in the milk and between <0.66 and 6.9 mg/L in the infant serum. The milk/maternal serum concentration ratio ranged from <0.18 to 0.74 and the infant/maternal serum concentration ratio measured between <0.15 and 0.74. Highly significant correlations were found between milk and maternal serum levels and between infant serum levels and milk, maternal serum levels, lamotrigine daily dose, and also maternal dose related to the body weight. CONCLUSIONS: The authors confirmed the wide range of the milk/maternal serum concentration ratio and the infant/maternal serum concentration ratio. Although the degree of lamotrigine exposure to the breastfed infants was smaller than during gestation, 16% of the infant serum levels measured were within the therapeutic range used for the general epileptic population. Lamotrigine concentration monitoring in breastfed infant, in our opinion, is the most relevant aspect for the analysis of actual lamotrigine exposure in infants, especially in those with clinical symptoms.

Valproic acid concentrations in nursing mothers, mature milk, and breastfed infants in monotherapy and combination therapy.

Valproic acid (VPA) is currently one of the four most often prescribed antiepileptic drugs (AEDs) in pregnancy. However, only a small number of studies have measured suckling infant serum levels of the drug. We studied the transport of VPA from breastfeeding mothers to the mature milk and breastfed infants and the influence of comedication with enzyme-inducing AEDs. The data of 30 nursing women treated by VPA were analyzed retrospectively. Mature milk, maternal, and infant serum levels were collected between the 6th and 32nd postnatal day and measured by gas chromatography during the years 1996-2017. Valproic acid levels varied from 5.4 to 69.0 mg/L (mean: 39.0 ±â€¯16.1 mg/L) in the maternal serum, from <1.0 to 16.7 mg/L (mean: 1.6 ±â€¯3.9 mg/L) in the milk, and from <1.0 to 17.5 mg/L (mean: 4.2 ±â€¯4.3 mg/L) in the infant serum. The milk/maternal serum level ratio ranged from <0.03 to 0.25 (mean: 0.03 ±â€¯0.06) and the infant/maternal serum level ratio from <0.03 to 0.61 (mean: 0.11 ±â€¯0.13). Sixty-seven percent of milk and 33% of infant VPA concentrations were below the limit of quantification. No correlations were observed between maternal serum and milk levels or between maternal and infant serum levels. In conclusion, none of the milk or infant serum VPA levels reached the lower limit of the reference range used for the general population with epilepsy, so the degree of VPA exposure in breastfed infants is less than during gestation. Nevertheless, if signs of potential adverse reactions manifest, infant serum concentrations should be measured.

What Does Antidepressant Drug level Monitoring Reveal About Outpatient Treatment and Patient Adherence?

INTRODUCTION: The evaluation of plasma levels of antidepressants may improve the treatment outcome. The aim was to verify adherence and adequacy of administered doses of antidepressants among patients hospitalized for inadequate outpatient therapeutic response. METHODS: Selective serotonin reuptake inhibitors or venlafaxine plasma levels were assessed on the first day of hospitalization and after 3 days of controlled administration. The patients were considered adherent if the plasma level on admission was within the interval of the minimum and maximum plasma level on the fourth day, expanded by 30%. The adequacy of antidepressant doses used during the outpatient treatment was assessed by comparing the plasma level on the fourth day with the therapeutic reference range. RESULTS: Out of 83 patients, 52 (62.7%) were adherent. The plasma levels of antidepressants on the fourth day were found to be within the therapeutic reference range in 35 (43.2%) patients. The same number manifested levels below the therapeutic reference range. In 11 (13.6%) patients, the levels were higher than recommended. No significant difference in rate of adherence was found among individual antidepressants. CONCLUSION: The results show that antidepressant nonresponders are frequently under-dosed or nonadherent.

Lamotrigine Drug Interactions in Combination Therapy and the Influence of Therapeutic Drug Monitoring on Clinical Outcomes of Adult Patients.

BACKGROUND: The aim was to study the impact of therapeutic drug monitoring (TDM) on patients on lamotrigine (LTG) therapy and the evaluation of possible drug interactions, especially in triple antiepileptic drug combinations. METHODS: During the period of 2001-2014, 3118 predose samples were taken from 1137 patients >15 years of age as part of their routine TDM. Drug interactions were evaluated using calculation of LTG clearance (CL). RESULTS: Valproic acid (VPA) decreased LTG CL by 66% in bitherapy, and by 35% and 31% in triple therapy with carbamazepine (CBZ) and phenytoin (PHT), respectively. CBZ and PHT increased LTG CL by 52% and 96% in respective bitherapies but by 88% in triple therapy. Clonazepam, levetiracetam, and topiramate had no effect. The LTG therapeutic range (TR) was exceeded in 1% of cases in monotherapy, and in 4%-5% of cases in combination therapy. Only 54% of results were within the TR during 2001-2005, whereas 60%-62% were within the TR during 2006-2014. Adverse drug reactions (ADRs) were reported in 88 cases and occurred more frequently during TR during 2001-2005. Higher number of supratherapeutic levels in combination therapy led to a 3-fold higher incidence of ADR and poorer seizure control, as seizures occurred more often monthly (2.5%) or a few per year (41%) and fewer patients were seizure free (18%). Seizures occurred more often daily and monthly during the first period and in patients with 3 or 4 drugs in combination. CONCLUSIONS: A significantly higher number of supratherapeutic levels were found in combinations with VPA, despite lower doses of LTG. Hepatic enzyme inducers, such as CBZ and PHT only partially compensated for the inhibitory effect of VPA. Decrease of both the frequency of seizures and the incidence of ADRs after TDM implementation suggests that TDM may have given clinicians the opportunity to achieve more optimal patient treatment.

Fast simultaneous LC/MS/MS determination of 10 active compounds in human serum for therapeutic drug monitoring in psychiatric medication.

A UPLC/MS/MS method with simple protein precipitation has been validated for the fast simultaneous analysis of agomelatine, asenapine, amisulpride, iloperidone, zotepine, melperone, ziprasidone, vilazodone, aripiprazole and its metabolite dehydro-aripiprazole in human serum. Alprenolol was applied as an internal standard. A BEH C18 (2.1 × 50 mm, 1.7 µm) column provided chromatographic separation of analytes using a binary mobile phase gradient (A, 2 mmol/L ammonium acetate, 0.1% formic acid in 5% acetonitrile, v/v/v; B, 2 mmol/L ammonium acetate, 0.1% formic acid in 95% acetonitrile, v/v/v). Mass spectrometric detection was performed in the positive electrospray ionization mode and ion suppression owing to matrix effects was evaluated. The validation criteria were determined: linearity, precision, accuracy, recovery, limit of detection, limit of quantification, reproducibility and matrix effect. The concentration range was as follows: 0.25-1000 ng/mL for agomelatine; 0.25-100 ng/mL for asenapine and iloperidone; 2.5-1000 ng/mL for amisulpride, aripiprazole, vilazodone and zotepine; 2.3-924.6 ng/mL for dehydroaripiprazole; 2.2-878.4 ng/mL for melperone; and 2.2-883.5 ng/mL for ziprasidone. Limits of quantitation below a therapeutic reference range were achieved for all analytes. Intra-run precision of 0.4-5.5 %, inter-run precision of 0.6-8.2% and overall recovery of 87.9-114.1% were obtained. The validated method was successfully implemented into routine practice for therapeutic drug monitoring in our hospital.

[Personalized pharmacotherapy of digoxin]. / Personalizovaná farmakoterapie digoxinem.

INTRODUCTION: Therapeutic and toxic effects of digoxin are related to its serum concentrations, recent evidence suggests that a lower therapeutic range 0.5-0.9 ng/ml is associated with reduced mortality. AIM: To show the advantages of therapeutic drug monitoring for dosing of digoxin. METHOD: Trough serum levels of digoxin were estimated by immunoassay MEIA (AxSym Abbott). The long term serum concentration - time profile of digoxin has been predicted by the Bayesian analysis computer program MW-Pharm 3.30 MediWare. RESULTS: Sex case reports of the patients between 71 to 92 years are presented to show the different doses to receive digoxin levels in the therapeutic range. The doses varies between 0.03-0.25 mg per day. CONCLUSION: Therapeutic drug monitoring is very usefull for prediction of serum level of digoxin. There is no need to wait for a steady-state condition before performing therapeutic drug monitoring.

[Therapeutic monitoring of amikacin and gentamicin in routine clinical practice]. / Terapeutické monitorování amikacinu a gentamicinu v rutinní klinické praxi.

Aminoglycosides constitute one of the oldest classes of antimicrobials. Despite their relative toxicity, mainly nephrotoxicity and ototoxicity, aminoglycosides are valuable in current clinical practice. They are bactericidal agents with activity against aerobic gram-negative infections and against gram-positive cocci when added to a cell wall active antimicrobial-based regimen (e.g. betalactams). Aminoglycosides have a concentration-dependent bactericidal effect and a long post antibiotic effect. There is accumulating evidence to show that large, single, daily doses (or more correctly, extended interval dosing) of aminoglycosides is associated with less nephrotoxicity and ototoxicity and comparable, if not superior clinical outcomes than the same total dose administered in small, multiple doses. The efficacy and toxicity of aminoglycosides show a strong direct positive relationship with blood drug concentrations. A key strategy in minimizing toxicity and optimizing therapy is therapeutic drug monitoring. Key words: aminoglycosides - amikacin - gentamicin - therapeutic monitoring.

[Therapeutic monitoring of vancomycin in routine clinical practice]. / Terapeutické monitorování vankomycinu v rutinní klinické praxi.

Therapeutic drug monitoring (TDM) is specific method of clinical pharmacology for monitoring of the therapy using measurement of drug serum concentrations followed interpretation and good cooperation with clinician. TDM help clinicians to quickly optimize vancomycin dosing regimens to maximize the clinical effect and minimize the toxicity of the drugs. Minimum serum vancomycin trough concentrations should always be maintained above 10 mg/L to avoid development of resistance, neverthelles trough concentrations > 20 mg/L are not recommended because of the risk of nephrotoxicity. For serious infections vancomycin trough concentrations of 15-20 mg/L are recommended and for a pathogen with an MIC of 1 mg/L, the minimum trough concentration would have to be at least 15 mg/L to generate the target AUC24/MIC 400 (area under the curve/minimal inhibitory concentration). In non-complicated infections trough concentrations of 10-15 mg/L should be sufficient. For continuous infusions of vancomycin target steady-state concentration values of 15-25 mg/L have been advocated for critically ill patients.Key words: therapeutic monitoring - trough concentration - vancomycin.

Therapeutic monitoring of lacosamide, perampanel, and zonisamide during breastfeeding.

OBJECTIVE: To provide additional information on the transport of the new anti-seizure medications lacosamide, perampanel, and zonisamide in breast milk and breastfed infants. METHODS: Between 2013 and 2022, concentrations of anti-seizure medications were measured in six women with epilepsy (each drug in two patients) using high-performance liquid chromatography. Additionally, concentrations were determined after two consecutive pregnancies in women receiving lacosamide and one woman receiving zonisamide. In all cases, anti-seizure medication concentrations were measured in the maternal serum and breast milk, and five cases, in the infant serum. RESULTS: For lacosamide, the ratios of breast milk/maternal serum concentration varied between 0.77 and 0.93, the ratios of infant/maternal serum concentrations were 0.16 and 0.35, and the ratios of infant serum/milk concentrations were 0.21 and 0.38. For perampanel, the ratios of breast milk/maternal serum concentration were 0.01 and 0.10 and the ratio of infant/maternal serum concentration was 0.36. For zonisamide, the ratios of breast milk/maternal serum concentration varied between 0.76 and 1.26, the ratios of infant/maternal serum concentrations between 0.44 and 0.85, and the ratios of infant serum/milk concentrations between 0.55 and 1.05. CONCLUSIONS: Breastfeeding is recommended for women using lacosamide, perampanel, and zonisamide. However, the actual exposure can only be accurately evaluated by determining the serum concentration of anti-seizure medication in breastfed infants.

Liquid chromatography-tandem mass spectrometry methods for quantification of total and free antibiotic concentrations in serum and exudate from patients with post-sternotomy deep sternal wound infection receiving negative pressure wound therapy.

BACKGROUND: Systemically administered antibiotics are thought to penetrate the wounds more effectively during negative pressure wound therapy (NPWT).To test this hypothesis total and free antibiotic concentrations were quantified in serum and wound exudate. METHODS: UHPLC-MS/MS methods were developed and validated for the determination of ceftazidime, cefepime, cefotaxime, cefuroxime, cefazolin, meropenem, oxacillin, piperacillin with tazobactam, clindamycin, ciprofloxacin, sulfamethoxazole/trimethoprim (cotrimoxazole), gentamicin, vancomycin, and linezolid. The unbound antibiotic fraction was obtained by ultrafiltration using a Millipore Microcon-30kda Centrifugal Filter Unit. Analysis was performed on a 1.7-µm Acquity UPLC BEH C18 2.1 × 100-mm column with a gradient elution. RESULTS: The validation was performed for serum, exudates and free fractions. For all matrices, requirements were met regarding linearity, precision, accuracy, limit of quantitation, and matrix effect. The coefficient of variation was in the range of 1.2-13.6%.and the recovery 87.6-115.6%, respectively. Among the 29 applications of antibiotics thus far, including vancomycin, clindamycin, ciprofloxacin, oxacillin, cefepime, cefotaxime, cotrimoxazole, and gentamicin, total and free antibiotic concentrations in serum and exudate were correlated. CONCLUSION: This method can accurately quantify the total and free concentrations of 16 antibiotics. Comparison of concentration ratios between serum and exudates allows for monitoring individual antibiotics' penetration capacity in patients receiving NPWT.

Serum teriflunomide concentrations in routine multiple sclerosis therapy: A cross-sectional pilot study.

BACKGROUND: Teriflunomide is administered orally to treat relapsing-remitting multiple sclerosis. In this prospective pilot study, the free and total serum concentrations of teriflunomide obtained during routine health care were measured and their relationship with disease activity was evaluated. METHODS: Eighty-nine patients were included in this study. Blood samples were collected from April 2021 to February 2022, and free and total teriflunomide serum concentrations were measured. Patient assessment involved monitoring of blood counts and potential adverse effects of teriflunomide. RESULTS: In the steady-state group, total teriflunomide concentrations ranged from 14.7 to 144.2 mg/L, while free concentrations from 31.1 to 389.7 µg/L. In the non-steady-state group, the total concentration ranged from 2.2 to 59.3 mg/L, with free concentrations ranging from 6.8 to 143.5 µg/L. In the steady-state group, a significant inverse correlation was found between absolute peripheral blood lymphocyte count and both total and free teriflunomide serum concentrations. CONCLUSION: Although all patients were treated with the same dose, up to a 10-fold difference in total and free teriflunomide serum concentrations, and up to a 5-fold difference in steady-state trough concentrations were observed. This vast interindividual variability can potentially lead to toxicity or, conversely, to suboptimal therapeutic concentrations of teriflunomide, with the risk of further worsening of multiple sclerosis compensation.

Analysis of Concentrations of Monomethyl Fumarate in Patients with Multiple Sclerosis: Result from Routine Health Care.

BACKGROUND: Dimethyl fumarate is used to treat patients with relapsing-remitting multiple sclerosis. After ingestion, it is rapidly hydrolyzed to the active primary metabolite monomethyl fumarate. OBJECTIVE: The main objective of our study was to analyze serum concentrations of monomethyl fumarate during routine health care in patients with multiple sclerosis treated with a fixed dose of dimethyl fumarate. METHODS: In the pilot cross-sectional study, data from 42 patients treated with dimethyl fumarate at a dose of 240 mg twice daily were collected. Concentrations of the active metabolite monomethyl fumarate were determined at 1-8 h (median, 3 h) or 10-14 h (median, 13 h) after taking the dose. The relationship between monomethyl fumarate concentrations and absolute lymphocyte count was evaluated. RESULTS: Concentrations of monomethyl fumarate ranged from 2.5-3177.9 µg/L, with most concentrations being undetectable approximately 10 hours after administration. In the 1-8 h (median, 3 h) post-dose subgroup, the concentration/dose ratio ranged widely from 0.04-6.62. The median concentration of monomethyl fumarate in the group with the absolute lymphocyte count <0.8 x 10^9/l was more than four times higher than in the group with the absolute lymphocyte count ≥0.8 x 10^9/l (median 440.1 µg/L versus 98.4 µg/L). CONCLUSION: The wide interindividual variability in monomethyl fumarate pharmacokinetics could contribute to the differential response to dimethyl fumarate in multiple sclerosis patients. A nonsignificant but noticeable trend was observed in the relationship of higher serum monomethyl fumarate concentrations to absolute lymphocyte counts.