Real-time Therapeutic Drug Monitoring Research Articles

An LC[sbnd]MS/MS method for the simultaneous determination of ten antimicrobials and its application in critically ill patients

Significant pharmacokinetic variation occurs in critically ill patients, leading to underexposure to antibiotics and poor prognosis. In this study, we developed a simple, sensitive, and fast liquid chromatography tandem mass spectrometry (LCMS/MS) platform for the simultaneous quantification of 8 antibacterial and 2 antifungal drugs, which is optimally suited for clinically efficient, real-time therapeutic drug monitoring (TDM). Multiple reaction monitoring (MRM) mass spectrometry was used in this method, and samples were prepared via protein precipitation with methanol. Chromatographic separation was accomplished on a BGIU Column-U02 (2.1ｘ50 mm, 3 µm), with six stable isotopes and one analog as an internal standard. The overall turnaround time of the assay was 5 minutes. All the drugs tested (piperacillin, cefoperazone, meropenem, levofloxacin, moxifloxacin, daptomycin, linezolid, vancomycin, fluconazole and voriconazole) were linear in the test concentration range (r ≥ 0.9900), the accuracy was 95 %-111 %, the precision variation coefficient was greater than or equal to 10 %, the lower limit of quantitation was 0.31–7.51 mg/L, and the coefficient of variation of the matrix factor was less than 10 %. The recovery rates ranged from 85 % to 115 %, and the antibiotics were stable at 4°C and −20°C for 6 days, with an offset of greater than or equal to 15 %. This method was successfully applied to routine TDM in 252 elderly critically ill patients.

High-dose individualized antithymocyte globulin with therapeutic drug monitoring in high-risk cord blood transplant

BackgroundGraft-versus-host disease (GvHD) and rejection are main limitations of cord blood transplantation (CBT), more so in patients with severe inflammation or previous rejections. While rigorous T-cell depletion with antithymocyte globulin (ATG) is needed to prevent GvHD and rejection, overexposure to ATG leads to slow T-cell recovery after transplantation, especially in CBT. ObjectiveTo evaluate high-dose, upfront ATG with individualized dosing and therapeutic drug monitoring (TDM) in pediatric CBT for patients at high risk for GvHD and rejection. Study designHeavily inflamed patients and patients with a recent history of rejection were eligible for individualized high-dose ATG with real-time TDM. The ATG dosing scheme was adjusted to target a post-CBT exposure of <10 AU*day/mL, while achieving a pre-CBT exposure of 60–120 AU*day/mL; exposure levels previously defined for optimal efficacy and safety in terms of reduced GvHD and rejection, respectively. Main outcomes of interest included efficacy (target exposure attainment) and safety (incidence of GvHD and rejection). Other outcomes of interest included T-cell recovery and survival. ResultsTwenty-one patients were included ranging from 2 months to 18 years old, receiving an actual median cumulative dose of ATG of 13.3 mg/kg (range 6–30 mg/kg) starting at a median 15 days (range 12–17) prior to CBT. Dosing was adjusted in 14 patients (increased in 3 and decreased in 11 patients). Eighteen (86%) and 19 (91%) patients reached the target pre-CBT and post-CBT exposure, respectively. Cumulative incidence for acute GvHD was 34% (95% CI 23–45) and 5% (95% CI 0–10%) for grade 2–4 and grade 3–4, respectively; cumulative incidence of rejection was 9% (95% CI 2–16%). Overall survival was 75% (95% CI 65–85%). ConclusionIndividualized high-dose ATG with TDM is feasible and safe for patients with hyperinflammation in a CBT setting. We observe high target ATG exposure attainment, good immune reconstitution (despite very high doses of ATG) and acceptable rates of GvHD and rejection.

Real-Time TDM-Guided Optimal Joint PK/PD Target Attainment of Continuous Infusion Piperacillin-Tazobactam Monotherapy Is an Effective Carbapenem-Sparing Strategy for Treating Non-Severe ESBL-Producing Enterobacterales Secondary Bloodstream Infections: Findings from a Prospective Pilot Study.

(1) Objectives: To assess the impact of optimal joint pharmacokinetic/pharmacodynamic (PK/PD) target attainment of continuous infusion (CI) piperacillin-tazobactam monotherapy on the microbiological outcome of documented ESBL-producing Enterobacterlaes secondary bloodstream infections (BSIs). (2) Methods: Patients hospitalized in the period January 2022-October 2023, having a documented secondary BSI caused by ESBL-producing Enterobacterales, and being eligible for definitive targeted CI piperacillin-tazobactam monotherapy according to specific pre-defined inclusion criteria (i.e., absence of septic shock at onset; favorable clinical evolution in the first 48 h after starting treatment; low-intermediate risk primary infection source) were prospectively enrolled. A real-time therapeutic drug monitoring (TDM)-guided expert clinical pharmacological advice (ECPA) program was adopted for optimizing (PK/PD) target attainment of CI piperacillin-tazobactam monotherapy. Steady-state plasma concentrations (Css) of both piperacillin and tazobactam were measured, and the free fractions (f) were calculated based on theoretical protein binding. The joint PK/PD target attainment was considered optimal whenever the piperacillin fCss/MIC ratio was >4 and the tazobactam fCss/target concentration (CT) ratio was >1 (quasi-optimal or suboptimal if only one or neither of the two thresholds were achieved, respectively). Univariate analysis was carried out for assessing variables potentially associated with failure in achieving the optimal joint PK/PD target of piperacillin-tazobactam and microbiological eradication. (3) Results: Overall, 35 patients (median age 79 years; male 51.4%) were prospectively included. Secondary BSIs resulted from urinary tract infections as a primary source in 77.2% of cases. The joint PK/PD target attainment was optimal in as many as 97.1% of patients (34/35). Microbiological eradication occurred in 91.4% of cases (32/35). Attaining the quasi-optimal/suboptimal joint PK/PD target of CI piperacillin-tazobactam showed a trend toward a higher risk of microbiological failure (33.3% vs. 0.0%; p = 0.08) (4) Conclusions: Real-time TDM-guided optimal joint PK/PD target attainment of CI piperacillin-tazobactam monotherapy may represent a valuable and effective carbapenem-sparing strategy when dealing with non-severe ESBL-producing Enterobacterales secondary BSIs.

Could an Optimized Joint Pharmacokinetic/Pharmacodynamic Target Attainment of Continuous Infusion Piperacillin-Tazobactam Be a Valuable Innovative Approach for Maximizing the Effectiveness of Monotherapy Even in the Treatment of Critically Ill Patients with Documented Extended-Spectrum Beta-Lactamase-Producing Enterobacterales Bloodstream Infections and/or Ventilator-Associated Pneumonia?

(1) Background: Piperacillin-tazobactam represents the first-line option for treating infections caused by full- or multi-susceptible Enterobacterales and/or Pseudomonas aeruginosa in critically ill patients. Several studies reported that attaining aggressive pharmacokinetic/pharmacodynamic (PK/PD) targets with beta-lactams is associated with an improved microbiological/clinical outcome. We aimed to assess the relationship between the joint PK/PD target attainment of continuous infusion (CI) piperacillin-tazobactam and the microbiological/clinical outcome of documented Gram-negative bloodstream infections (BSI) and/or ventilator-associated pneumonia (VAP) of critically ill patients treated with CI piperacillin-tazobactam monotherapy. (2) Methods: Critically ill patients admitted to the general and post-transplant intensive care unit in the period July 2021-September 2023 treated with CI piperacillin-tazobactam monotherapy optimized by means of a real-time therapeutic drug monitoring (TDM)-guided expert clinical pharmacological advice (ECPA) program for documented Gram-negative BSIs and/or VAP were retrospectively retrieved. Steady-state plasma concentrations (Css) of piperacillin and of tazobactam were measured, and the free fractions (f) were calculated according to respective plasma protein binding. The joint PK/PD target was defined as optimal whenever both the piperacillin fCss/MIC ratio was >4 and the tazobactam fCss/target concentration (CT) ratio was > 1 (quasi-optimal or suboptimal whenever only one or none of the two weas achieved, respectively). Multivariate logistic regression analysis was performed for testing variables potentially associated with microbiological outcome. (3) Results: Overall, 43 critically ill patients (median age 69 years; male 58.1%; median SOFA score at baseline 8) treated with CI piperacillin-tazobactam monotherapy were included. Optimal joint PK/PD target was attained in 36 cases (83.7%). At multivariate analysis, optimal attaining of joint PK/PD target was protective against microbiological failure (OR 0.03; 95%CI 0.003-0.27; p = 0.002), whereas quasi-optimal/suboptimal emerged as the only independent predictor of microbiological failure (OR 37.2; 95%CI 3.66-377.86; p = 0.002). (4) Conclusion: Optimized joint PK/PD target attainment of CI piperacillin-tazobactam could represent a valuable strategy for maximizing microbiological outcome in critically ill patients with documented Gram-negative BSI and/or VAP, even when sustained by extended-spectrum beta-lactamase (ESBL)-producing Enterobacterales. In this scenario, implementing a real-time TDM-guided ECPA program may be helpful in preventing failure in attaining optimal joint PK/PD targets among critically ill patients. Larger prospective studies are warranted to confirm our findings.

Role of a Real-Time TDM-Based Expert Clinical Pharmacological Advice Program in Optimizing the Early Pharmacokinetic/Pharmacodynamic Target Attainment of Continuous Infusion Beta-Lactams among Orthotopic Liver Transplant Recipients with Documented or Suspected Gram-Negative Infections.

(1) Objectives: To describe the attainment of optimal pharmacokinetic/pharmacodynamic (PK/PD) targets in orthotopic liver transplant (OLT) recipients treated with continuous infusion (CI) beta-lactams optimized using a real-time therapeutic drug monitoring (TDM)-guided expert clinical pharmacological advice (ECPA) program during the early post-surgical period. (2) Methods: OLT recipients admitted to the post-transplant intensive care unit over the period of July 2021-September 2023, receiving empirical or targeted therapy with CI meropenem, piperacillin-tazobactam, meropenem-vaborbactam, or ceftazidime-avibactam optimized using a real-time TDM-guided ECPA program, were retrospectively retrieved. Steady-state beta-lactam (BL) and/or beta-lactamase inhibitor (BLI) plasma concentrations (Css) were measured, and the Css/MIC ratio was selected as the best PK/PD target for beta-lactam efficacy. The PK/PD target of meropenem was defined as being optimal when attaining a fCss/MIC ratio > 4. The joint PK/PD target of the BL/BLI combinations (namely piperacillin-tazobactam, ceftazidime-avibactam, and meropenem-vaborbactam) was defined as being optimal when the fCss/MIC ratio > 4 of the BL and the fCss/target concentration (CT) ratio > 1 of tazobactam or avibactam, or the fAUC/CT ratio > 24 of vaborbactam were simultaneously attained. Multivariate logistic regression analysis was performed for testing potential variables that were associated with a failure in attaining early (i.e., at first TDM assessment) optimal PK/PD targets. (3) Results: Overall, 77 critically ill OLT recipients (median age, 57 years; male, 63.6%; median MELD score at transplantation, 17 points) receiving a total of 100 beta-lactam treatment courses, were included. Beta-lactam therapy was targeted in 43% of cases. Beta-lactam dosing adjustments were provided in 76 out of 100 first TDM assessments (76.0%; 69.0% decreases and 7.0% increases), and overall, in 134 out of 245 total ECPAs (54.7%). Optimal PK/PD target was attained early in 88% of treatment courses, and throughout beta-lactam therapy in 89% of cases. Augmented renal clearance (ARC; OR 7.64; 95%CI 1.32-44.13) and MIC values above the EUCAST clinical breakpoint (OR 91.55; 95%CI 7.12-1177.12) emerged as independent predictors of failure in attaining early optimal beta-lactam PK/PD targets. (4) Conclusion: A real-time TDM-guided ECPA program allowed for the attainment of optimal beta-lactam PK/PD targets in approximately 90% of critically ill OLT recipients treated with CI beta-lactams during the early post-transplant period. OLT recipients having ARC or being affected by pathogens with MIC values above the EUCAST clinical breakpoint were at high risk for failure in attaining early optimal beta-lactam PK/PD targets. Larger prospective studies are warranted for confirming our findings.

Real-Time TDM-Based Expert Clinical Pharmacological Advice Program for Attaining Aggressive Pharmacokinetic/Pharmacodynamic Target of Continuous Infusion Meropenem in the Treatment of Critically Ill Patients with Documented Gram-Negative Infections Undergoing Continuous Veno-Venous Hemodiafiltration.

(1) Objectives: to describe the pharmacokinetic/pharmacodynamic (PK/PD) profile of continuous infusion (CI) meropenem in critical patients with documented Gram-negative infections undergoing continuous veno-venous hemodiafiltration (CVVHDF) and to assess the relationship with microbiological outcome. (2) Methods: Data were retrospectively retrieved for patients admitted to the general and the post-transplant intensive care units in the period October 2022-May 2023 who underwent CVVHDF during treatment with CI meropenem optimized by means of a real-time therapeutic drug monitoring (TDM)-based expert clinical pharmacological advice (ECPA) program for documented Gram-negative infections. Steady-state meropenem plasma concentrations were measured, and the free fractions (fCss) were calculated. Meropenem total clearance (CLtot) was calculated at each TDM assessment, and the impact of CVVHDF dose intensity and of residual diuresis on CLtot was investigated by means of linear regression. Optimal meropenem PK/PD target attainment was defined as an fCss/MIC ratio > 4. The relationship between meropenem PK/PD target attainment and microbiological outcome was assessed. (3) Results: A total of 24 critical patients (median age 68 years; male 62.5%) with documented Gram-negative infections were included. Median (IQR) meropenem fCss was 19.9 mg/L (17.4-28.0 mg/L). Median (IQR) CLtot was 3.89 L/h (3.28-5.29 L/h), and median (IQR) CVVHDF dose intensity was 37.4 mL/kg/h (33.8-44.6 mL/kg/h). Meropenem dosing adjustments were provided in 20 out of 24 first TDM assessments (83.3%, all decreases) and overall in 26 out of the 51 total ECPA cases (51.0%). Meropenem PK/PD target attainment was always optimal, and microbiological eradication was achieved in 90.5% of assessable cases. (4) Conclusion: the real-time TDM-guided ECPA program was useful in attaining aggressive PK/PD targeting with CI meropenem in critically ill patients undergoing high-intensity CVVHDF and allowed microbiological eradication in most cases with dosing regimens ranging between 125 and 500 mg q6h over 6 h.

Pharmacokinetic/Pharmacodynamic Target Attainment of Continuous Infusion Piperacillin-Tazobactam or Meropenem and Microbiological Outcome among Urologic Patients with Documented Gram-Negative Infections.

(1) Objectives: To describe the relationship between pharmacokinetic/pharmacodynamic (PK/PD) target attainment of continuous infusion (CI) piperacillin-tazobactam or meropenem monotherapy and microbiological outcome in a case series of urological patients with documented Gram-negative infections. (2) Methods: Patients admitted to the urology ward who were treated with CI piperacillin-tazobactam or meropenem monotherapy for documented Gram-negative infections and underwent real-time therapeutic drug monitoring (TDM)-guided expert clinical pharmacological advice (ECPA) program from June 2021 to May 2023 were retrospectively retrieved. Average steady-state (Css) piperacillin-tazobactam and meropenem concentrations were determined, and the free fractions (fCss) were calculated. Optimal PK/PD target attainments were defined as an fCss/MIC ratio >4 for CI meropenem and an fCss/MIC ratio of piperacillin >4 coupled with an fCss/CT ratio for tazobactam >1 for piperacillin-tazobactam (joint PK/PD target). The relationship between beta-lactam PK/PD targets and microbiological outcome was explored. (3) Results: Sixteen urologic patients with documented Gram-negative infections (62.5% complicated urinary tract infections (cUTI)) had 30 TDM-guided ECPAs. At first TDM assessment, beta-lactam dosing adjustments were recommended in 11 out of 16 cases (68.75%, of which 62.5% decreases and 6.25% increases). Overall, beta-lactam dosing adjustments were recommended in 14 out of 30 ECPAs (46.6%). Beta-lactam PK/PD target attainments were optimal in 100.0% of cases. Microbiological failure occurred in two patients, both developing beta-lactam resistance. (4) Conclusion: A TDM-guided ECPA program may allow for optimizing beta-lactam treatment in urologic patients with documented Gram-negative infections, ensuring microbiological eradication in most cases.

Relationship Between Real-time TDM-guided Pharmacodynamic Target Attainment of Continuous Infusion Beta-lactam Monotherapy and Microbiologic Outcome in the Treatment of Critically Ill Children With Severe Documented Gram-negative Infections.

To explore the relationship between real-time therapeutic drug monitoring (TDM)-guided pharmacodynamic target attainment of continuous infusion (CI) beta-lactam monotherapy and microbiological outcome in the treatment of critically ill children with severe documented Gram-negative infections. Observational, monocentric, retrospective study of critically ill patients receiving CI piperacillin-tazobactam, ceftazidime, or meropenem in monotherapy for documented Gram-negative infections optimized by means of a real-time TDM-guided strategy. Average steady-state beta-lactam concentrations (Css) were calculated for each patient, and the beta-lactam Css/minimum inhibitory concentration (MIC) ratio was selected as a pharmacodynamic parameter of efficacy. The Css/MIC ratio was defined as optimal if ≥4, quasi-optimal if between 1 and 4, and suboptimal if <1. The relationship between Css/MIC and microbiological outcome was assessed. Forty-six TDM assessments were carried out in 21 patients [median age 2 (interquartile range: 1-8) years]. Css/MIC ratios were optimal in 76.2% of cases. Patients with optimal Css/MIC ratios had both a significantly higher microbiological eradication rate (75.0% vs. 0.0%; P = 0.006) and lower resistance development rate (25.0% vs. 80.0%; P = 0.047) than those with quasi-optimal or suboptimal Css/MIC ratios. Quasi-optimal/suboptimal Css/MIC ratio occurred more frequently when patients had infections caused by pathogens with MIC values above the European Committee on Antimicrobial Susceptibility Testing clinical breakpoint (100.0% vs. 6.3%; P < 0.001). Real-time TDM-guided pharmacodynamic target attainment of CI beta-lactam monotherapy allowed to maximize treatment efficacy in most critically ill children with severe Gram-negative infections. Attaining early optimal Css/MIC ratios of CI beta-lactams could be a key determinant associated with microbiological eradication during the treatment of Gram-negative infections. Larger prospective studies are warranted for confirming our findings.

A novel method to evaluate ceftazidime/avibactam therapy in patients with carbapenemase-producing Enterobactericeae (CPE)bloodstream infections.

This study reports experience managing eight patients with bloodstream infections treated with a continuous infusion of ceftazidime-avibactam. Patients who were treated for documented CPE BSIs susceptible to CAZ-AVI and who underwent real-time therapeutic drug monitoring were retrospectively assessed. Ceftazidime MICs were assessed in presence of increasing concentrations of avibactam by the broth microdilution method. An inhibitory sigmoid Emax model was used to characterize ceftazidime MIC reduction as a function of avibactam concentration, and the MICi was derived by conditioning the best-fit model using steady-state avibactam concentrations (Css). Ceftazidime fCss/MICi ratio was calculated for each patient and correlated to microbiological outcome. By adopting the innovative concept of effective MIC with an inhibitor (MICi), a trend towards higher microbiological failure and resistance development was found in patients with a lower ceftazidime fCss/MICi ratio (2/3 vs. 0/5). Assessment of changes in the ceftazidime MIC in relation to increasing avibactam concentration could represent a more robust pharmacokinetic/pharmacodynamic method for predicting microbiological failure given beta-lactam/beta-lactamase inhibitor combinations.

Early Target Attainment With Continuous Infusion Meropenem and Piperacillin/Tazobactam and Utilization of Therapeutic Drug Monitoring in Critically Ill Patients: A Retrospective Cohort Study From 2017 to 2020.

We analyzed the attainment of early pharmacological targets of continuous infusion meropenem and piperacillin/tazobactam and the use and effect of a real-time therapeutic drug monitoring (TDM) program on subsequent dosing and target attainment in patients who are critically ill. This was a single-center, retrospective study among patients hospitalized in the intensive care unit in a Swiss tertiary care hospital from 2017 to 2020. The primary outcome was target attainment [100% tT ≥ 4xECOFF (Pseudomonas aeruginosa)] of continuous infusion meropenem and piperacillin/tazobactam within 72 hours after initiation of treatment. A total of 234 patients were included. Median first meropenem (n = 186 of 234) and piperacillin (n = 48 of 234) concentration was 21 mg/L (interquartile range [IQR], 15.6-28.6) and 100.7 mg/L (IQR, 64.0-160.2), respectively. Pharmacological target was attained in 95.7% (95% confidence interval [CI], 91.7-98.1) of patients receiving meropenem and 77.0% (95% CI, 62.7-87.9) treated with piperacillin/tazobactam. In the univariable and multivariable logistic regression, body weight and estimated glomerular filtration rate were negatively associated with target attainment. Subsequently, meropenem dosage was decreased or stopped in 35 of 186 (18.8%) and 89 of 186 (47.9%) patients, respectively, and increased in 2 of 186 (1.1%) patients. Continuous infusion meropenem and piperacillin/tazobactam yielded excellent and moderate early pharmacological target attainment in critically ill patients, respectively. The TDM was mainly used to decrease meropenem dosage.

A Novel Approach for Therapeutic Drug Monitoring of Valproic Acid Using FT-IR Spectroscopy and Nonlinear Support Vector Regression.

Recent technological progress has bolstered efforts to bring personalized medicine from theory into clinical practice. However, progress in areas such as therapeutic drug monitoring (TDM) has remained somewhat stagnant. In drugs with well-known dose-response relationships, TDM can enhance patient outcomes and reduce health care costs. Traditional monitoring methods such as chromatography-based or immunoassay techniques are limited by their higher costs and slow turnaround times, making them unsuitable for real-time or onsite analysis. In this work, we propose the use of a fast, direct, and simple approach using Fourier transform infrared spectroscopy (FT-IR) combined with chemometric techniques for the therapeutic monitoring of valproic acid (VPA). In this context, a database of FT-IR spectra was constructed from human plasma samples containing various concentrations of VPA; these samples were characterized by the reference method (immunoassay technique) to determine the VPA contents. The FT-IR spectra were processed by two chemometric regression methods: partial least-squares regression (PLS) and support vector regression (SVR). The results provide good evidence for the effectiveness of the combination of FT-IR spectroscopy and SVR modeling for estimating VPA in human plasma. SVR models showed better predictive abilities than PLS models in terms of root-mean-square error of calibration and prediction RMSEC, RMSEP, R2Cal, R2Pred, and residual predictive deviation (RPD). This analytical tool offers potential for real-time TDM in the clinical setting. FTIR spectroscopy was evaluated for the first time to predict VPA in human plasma for TDM. Two regressions were evaluated to predict VPA in human plasma, and the best-performing model was obtained using nonlinear SVR.

Real-World Comparison of Isavuconazole and Voriconazole in Terms of the Need for Dosage Adjustments Guided by Clinical Pharmacological Advice During Primary Prophylaxis of Invasive Fungal Infections in Pediatric Patients with Hemato-Oncological Malignancies.

Limited evidence concerning optimal azole dosing regimens currently exists for antifungal prophylaxis in hemato-oncological pediatric patients. Hemato-oncological children receiving intravenous or oral isavuconazole or voriconazole for primary antifungal prophylaxis at IRCCS Azienda Ospedaliero-Universitaria of Bologna during November 2020 to October 2021 and undergoing CPA programs based on real-time therapeutic drug monitoring (TDM) were retrospectively analyzed. CPAs for isavuconazole and voriconazole and the number of dosage adjustments were collected. Normalized trough concentrations [(C min )/dose/kg] were calculated for both drugs at each TDM assessment, and the coefficient of variation was determined. The efficacy and safety of the drugs were evaluated. Sixteen hemato-oncological pediatric patients received azole prophylaxis (mean age and weight: 9.1 ± 4.9 years and 32.6 ± 16.0 kg; 6 isavuconazole and 10 voriconazole). Sixty and 89 CPAs were delivered as isavuconazole and voriconazole, respectively. Dosage adjustments were needed in 3.3% of cases for isavuconazole and 53.9% of cases for voriconazole ( P < 0.001). At first TDM, achievement of the desired target during standard dosing regimens was higher for isavuconazole (83.3%) than for voriconazole (10.0%; P = 0.008). Dispersion of normalized concentrations was higher for voriconazole (CV = 139.1% vs. CV = 79.4%). Elevation of ALT and aspartate aminotransferase levels between baseline and the third month was higher in patients receiving voriconazole (median, 28 vs. 90 U/L; P = 0.038, and 19 vs. 65.5 U/L; P = 0.002). Our findings suggest that there is limited variability in isavuconazole exposure in hemato-oncological pediatric patients receiving azole prophylaxis , resulting in a low need for CPA-guided dosage adjustments.

A Proof of Concept of the Usefulness of a TDM-Guided Strategy for Optimizing Pharmacokinetic/Pharmacodynamic Target of Continuous Infusion Ampicillin-Based Regimens in a Case Series of Patients with Enterococcal Bloodstream Infections and/or Endocarditis.

(1) Objective: To describe the usefulness of a real-time therapeutic drug monitoring (TDM)-based strategy for optimizing pharmacokinetic/pharmacodynamic (PK/PD) target attainment of continuous infusion (CI) ampicillin-based regimens in a case series of patients affected by suspected or documented enterococcal bloodstream infections (BSIs) and/or infective endocarditis (IE). (2) Methods: Patients treated with CI ampicillin-based regimens for documented or suspected enterococcal BSI/IE who underwent real-time therapeutic drug monitoring (TDM)-based expert clinical pharmacological advice (ECPA) between June 2021 and May 2022 were retrospectively assessed. Ampicillin concentrations were determined at steady state, and the free fraction (fCss) was calculated according to a plasma protein binding of 20%. The fCss/MIC ratio was selected as the PD parameter for ampicillin efficacy and was defined as optimal for values between 4 and 8. The requirement for TDM-guided ampicillin dosing adjustments was assessed. (3) Results: Data for 12 patients with documented (n = 10) or suspected (n = 2) enterococcal infections (7 with BSIs and 5 with IE) were retrieved. The ampicillin PK/PD target was optimal over time in all of the 10 documented infections. None of the enterococcal BSIs persisted. Following the first real-time TDM-based ECPA, ampicillin dosage was decreased by >50% in 11 out of 12 patients (91.7%). (4) Conclusions: CI may be helpful in attaining aggressive ampicillin PK/PD targets in patients affected by enterococcal BSIs and/or IE. Administration of CI ampicillin after loading coupled with real-time TDM-based ECPA could be a valuable strategy for managing enterococcal infections.

Microneedle Aptamer-Based Sensors for Continuous, Real-Time Therapeutic Drug Monitoring.

The ability to continuously monitor the concentration of specific molecules in the body is a long-sought goal of biomedical research. For this purpose, interstitial fluid (ISF) was proposed as the ideal target biofluid because its composition can rapidly equilibrate with that of systemic blood, allowing the assessment of molecular concentrations that reflect full-body physiology. In the past, continuous monitoring in ISF was enabled by microneedle sensor arrays. Yet, benchmark microneedle sensors can only detect molecules that undergo redox reactions, which limits the ability to sense metabolites, biomarkers, and therapeutics that are not redox-active. To overcome this barrier, here, we expand the scope of these devices by demonstrating the first use of microneedle-supported electrochemical, aptamer-based (E-AB) sensors. This platform achieves molecular recognition based on affinity interactions, vastly expanding the scope of molecules that can be sensed. We report the fabrication of microneedle E-AB sensor arrays and a method to regenerate them for multiple uses. In addition, we demonstrate continuous molecular measurements using these sensors in flow systems in vitro using single and multiplexed microneedle array configurations. Translation of the platform to in vivo measurements is possible as we demonstrate with a first E-AB measurement in the ISF of a rodent. The encouraging results reported in this work should serve as the basis for future translation of microneedle E-AB sensor arrays to biomedical research in preclinical animal models.

Successful Treatment of Bacteremia and Ventilator-Associated Pneumonia Caused by KPC/OXA-48-like Klebsiella pneumoniae Co-Producer with a Continuous Infusion of High-Dose Meropenem Plus Fosfomycin Guided by Real-Time Therapeutic Drug Monitoring.

Bacteremia and ventilator-associated pneumonia due to a pan-resistant Klebsiella pneumoniae strain co-producing KPC and OXA-48 carbapenemases was successfully treated in a COVID-19 critically ill patient with a combination therapy of a high-dose continuous infusion of meropenem (up to 3 g every 6 h, daily) plus fosfomycin (up to 24 g/daily) that was guided by real-time therapeutic drug monitoring. Clinical pharmacological advice was helpful in maximizing, over time, the pharmacodynamic target attainment of both antibiotics.

Optimizing antimicrobial use: challenges, advances and opportunities.

An optimal antimicrobial dose provides enough drug to achieve a clinical response while minimizing toxicity and development of drug resistance. There can be considerable variability in pharmacokinetics, for example, owing to comorbidities or other medications, which affects antimicrobial pharmacodynamics and, thus, treatment success. Although current approaches to antimicrobial dose optimization address fixed variability, better methods to monitor and rapidly adjust antimicrobial dosing are required to understand and react to residual variability that occurs within and between individuals. We review current challenges to the wider implementation of antimicrobial dose optimization and highlight novel solutions, including biosensor-based, real-time therapeutic drug monitoring and computer-controlled, closed-loop control systems. Precision antimicrobial dosing promises to improve patient outcome and is important for antimicrobial stewardship and the prevention of antimicrobial resistance.

Molecularly Imprinted Carbon-Paste for Theophylline Sensing on a Disposable Paper Chip Sensor

Introduction Molecularly imprinted polymers (MIPs) are recognition elements with specific cavities designed for a particular target molecule. Recently, MIPs have been used in various applications explicitly requiring molecular recognition. In MIPs, the crosslinking monomers and functional monomers, having an affinity with a target molecule, are copolymerized in the presence of the target or the template molecule. Upon selective removal of the template molecule, imprinted cavities are formed. MIPs provide a wide range of benefits, including mechanical reliability, cost-effectiveness, and rapid mass production, and have recently been used for various applications, especially in biosensing areas [1]–[3].Theophylline (THO) is a drug commonly used for the therapy of respiratory diseases. However, owing to its highly toxic nature, an overdose can induce paralysis, seizures, and even death.[4] Additionally, the therapeutic window of THO is relatively small (5-15 mgmL-1) [4],[5], and therefore, the therapeutic drug monitoring (TDM) of theophylline is highly significant [5]. In this study, molecularly imprinted polymers grafted carbon pastes were prepared for THO sensing. The commonly used functional monomer, methacrylic acid, crosslinking monomers, N, N’-methylenebisacrylamide (MBAA), and ethylene glycol dimethacrylate (EDMA) were used, and the MIPs thus formed were evaluated using differential pulse voltammetry on a paper chip. Methods Fig. 1 shows the scheme of the paper chip along with the sensing response of theophylline MIP. The paper chip composed of a photo-paper base with electrodes printed using conductive ink through an inkjet printer. The holes for electrodes (working electrode, a reference electrode, and counter electrode) and reservoir are cut on laminating sheets using a laser cutter. The three parts are then attached using the laminator. The reference electrode is packed with Ag/AgCl ink and dried overnight at 60 ℃. The counter electrode with the printed conductive ink is used as it is. The MIP-grafted carbon paste is packed in the working electrode with the help of a glass tube. The theophylline imprinted poly(methylene bisacrylamide-co-ethylene dimethacrylate-co-methacrylic acid) was grafted on the graphite particle surface by a procedure similar to our previous work [3], [6]. This grafted graphite was mixed with ferrocene containing silicone oil to make a paste used as the sensing material. We performed the differential pulse voltammetry with theophylline sample solution (in saline buffer with pH 7.4, 0-40 mgmL-1 and whole bovine blood) filled in the sample-reservoir. Results and Conclusions The execution time of each voltammetry was 2 min only. The plot in Fig. 1 shows the influence of the theophylline concentration on the redox current at 0.8 V at the MIP-carbon paste electrode in both buffer saline and whole bovine blood. It is quite evident from the figure that MIP is sensitive towards theophylline in both buffer and whole blood. It indicates that MIP activates the electrocatalytic behavior of the carbon-paste electrode. The dynamic range at the MIP electrode versus the concentration of theophylline is seen in the range of 0-40 mgmL-1, which covers the therapeutically effective theophylline concentration level in plasma varying from 5 to 15 mgmL-1. The DPV measurements at each concentration has been done using a new chip every time, i.e. ‘single-use’ of the chip. Additionally, no reagents have been added during the analysis, thus making the procedure of drug level measurement simple. From the results of this study, it can be concluded that the proposed method is useful for quick and straightforward real-time TDM to prevent the toxic side effects of an overdose.

Pharmacokinetic/pharmacodynamic target attainment in critically ill renal patients on antimicrobial usage: focus on novel beta-lactams and beta lactams/beta-lactamase inhibitors

ABSTRACT Introduction Several novel beta-lactams (BLs) and/or beta lactams/beta-lactamase inhibitors (BL/BLIs) have been recently developed for the management of multidrug-resistant bacterial infections. Data concerning dose optimization in critically ill patients with altered renal function are scanty. Areas covered This article provides a critical reappraisal of pharmacokinetic and clinical issues emerged with novel BLs and/or BL/BLIs in renal critically ill patients. Clinical and pharmacokinetic studies published in English until December 2020 were searched on the PubMed-MEDLINE database. Expert opinion Several issues emerged with the use of novel BLs and/or BL/BLIs in critically ill renal patients. Suboptimal clinical response rate with ceftazidime-avibactam and ceftolozane-tazobactam was reported in phase II–III trials in patients with moderate kidney injury; data on patients undergoing renal replacement therapy are limited to some case reports; dose adjustment in augmented renal clearance is provided only for cefiderocol. Implementation of altered dosing strategies (prolonged infusion and/or higher dosage) coupled with adaptive real-time therapeutic drug monitoring could represent the most effective approach in warranting optimal pharmacokinetic/pharmacodynamic targets with novel BLs and/or BL/BLIs in challenging scenarios, thus minimizing the risk of clinical failure and/or of resistance selection.

Cure of Limb-Threatening XDR Pseudomonas aeruginosa Infection: Combining Genome Sequencing, Therapeutic Drug Level Monitoring, and Surgical Debridement

We describe a case of limb-threatening osteomyelitis and metalware infection with carbapenemase-producing extensively drug-resistant Pseudomonas aeruginosa successfully cured with aggressive surgical debridement and combined intravenous fosfomycin and colistin. Real-time therapeutic drug monitoring was used to maximize probability of efficacy and minimize potential for toxicity.

(Invited) Extending the Stability of Electrochemical, Aptamer-Based Sensors In Vivo

Electrochemical aptamer-based (E-AB) sensors are a technology that enables precise measurements of specific molecular targets in the body. They have been demonstrated to support real-time therapeutic drug monitoring and feedback-controlled drug dosing in living animals. However, one drawback of E-AB sensors is the rapid degradation of their sensing interface upon continuous interrogation via, for example, voltammetry. Over time, the faradaic current from their aptamer-attached redox reporter decreases, and the currents from charging the electrical double-layer increase beyond the faradaic current, thus preventing signaling. The latter effect is due to progressive desorption of the electrode-passivating alkyl thiol monolayers employed in these sensors. This progressive degradation limits their in-vivo operational life to hours, a period too short for monitoring the vast majority of drugs in humans. Attempting to address this problem, my laboratory is investigating novel monolayer chemistries that extend the operational life of E-AB sensors without compromising their sensing performance or biocompatibility. In this presentation, I will discuss the effects that different monolayer chemistries have on E-AB sensing performance and how they extend the in-vitro operational life of E-AB sensors for days in undiluted biological fluids.