Trough Levels Research Articles

Analysis of Nirmatrelvir Entry into Pulmonary Lining Fluid in Patients with COVID-19: A Unique Perspective to Explore and Understand the Target Plasma Concentration of 292 ng/mL in Antiviral Activity.

Currently, the applicant has chosen a target plasma trough concentration for nirmatrelvir, which is adjusted to 292 ng/mL based on the drug's molecular weight (499.54 Daltons), its binding to human plasma proteins (69%), and the in vitro antiviral EC90 value (181 nM). However, the current exposure-effect relationships (ER) analysis of viral load in patients enrolled in the EPIC-HR study has not revealed clinically significant trends in the ER. Given that the lungs are the primary site of COVID-19 infection, we aim to further understand this exposure relationship by exploring and analyzing the penetration characteristics of nirmatrelvir in the lungs. To explore and understand the target plasma concentration of 292 ng/mL in antiviral activity. We identified all critically ill patients with coronavirus disease 2019 who received nirmatrelvir/ritonavir treatment in the respiratory intensive care unit of Changhai hospital between January 2023 and October 2023. Samples of plasma and bronchoalveolar lavage fluid were obtained at pre-dose trough concentrations after administration of nirmatrelvir (NMV). The relationship between NMV levels in plasma and the epithelial lining fluid (ELF) was assessed by determining concentrations of NMV. There was a significant relationship between NMV levels in plasma and ELF (ELF = 0.4976*PLASMA- 204; R = 0.96), with a correlation whose slope (0.4976) suggested that the blood-to-ELF ratio of drug penetration was 2:1. A negative value from the equation indicates that NMV requires to reach baseline concentration to penetrate the ELF. The relationship between NMV levels in plasma and ELF with low permeability and a negative baseline value suggests that the target plasma concentration of 292 ng/mL is insufficient for antiviral activity. This study provides a unique perspective to explore and understand no clinically meaningful trend of exposure-response relationships in patients enrolled in EPIC-HR.

The Loss-of-Function ATP Binding Cassette Subfamily G Member 2 Polymorphism ABCG2 c.421C>A Reduces Lamotrigine Trough Concentrations in Adults with Epilepsy.

The commonly used antiseizure medication lamotrigine is a substrate to ATP binding cassette subfamily G member 2 (ABCG2) transporter. The objective of this study was to evaluate the effect of the common loss-of-function polymorphism ABCG2 c.421C>A (rs2231142) on the lamotrigine trough concentrations at steady state in adults with epilepsy. In two consecutive studies (Study 1, Study 2) in patients on lamotrigine monotherapy, carriers of the variant ABCG2 c.421C>A allele (CA/AA) were considered exposed, and wild-type homozygotes (CC) were considered controls. They were mutually balanced on covariates (age, sex, body weight, several polymorphisms in genes encoding other transporter proteins and lamotrigine-metabolizing enzymes that have been suggested to affect exposure to lamotrigine) to estimate the exposure effect (geometric means ratios, GMRs) in each study separately and overall (individual patient data meta-analysis). The overall estimate was evaluated for sensitivity to residual confounding. In both studies (exposed n = 28 vs. controls n = 103; exposed n = 44 vs. controls n = 153, in Study 1 and Study 2, respectively) and overall (exposed n = 72 vs. controls n = 256), dose-corrected lamotrigine trough concentrations were moderately lower in the exposed patients: frequentist GMR [95% CI] = 0.82 [0.63-1.08]; GMR = 0.69 [0.60-0.81] and GMR = 0.72 [0.63-0.83] in Study 1, Study 2 and overall, respectively; Bayes GMR [95% CrI] = 0.83 [0.68-1.00]; GMR = 0.69 [0.58-0.83] and GMR = 0.75 [0.65-0.86] in Study 1, Study 2 and overall, respectively. Estimates appeared resistant to unmeasured confounding-the E-values for the pooled point estimates were high, and estimates corrected for a strong hypothetical bias were GMR = 0.78 [0.68-0.90] frequentist and GMR = 0.81 [0.70-0.93] Bayes. Polymorphism ABCG2 c.421C>A moderately reduces lamotrigine concentrations in adults with epilepsy.

Dosing strategy of tacrolimus when co-administered with Wuzhi tablet in renal transplant recipients.

Tacrolimus (TAC) is a first-line immunosuppressant to prevent allograft rejection. Wuzhi tablet is widely used as a TAC-sparing agent in China that could significantly elevate TAC exposure. However, insufficient data support the dose recommendation of TAC when co-administered with Wuzhi. A total of 305 adult renal transplant patients with 2,541 TAC trough concentrations (C0) were enrolled for population pharmacokinetic (PPK) modeling. CYP3A5 polymorphism was genotyped, and corresponding clinical factors were recorded. Nonlinear mixed-effects modeling and Monte Carlo simulation were used for dose recommendation. PK parameters were calculated based on one-compartment model with first-order absorption and elimination. The estimated total clearance (CL/F) and volume of distribution (Vd/F) of TAC were 23.84 L/h and 1,075.96 L, respectively. Wuzhi, CYP3A5 genotype, hematocrit (HCT), and weight were found to have a significant influence on CL/F. CL/F was significantly lower in the individuals who were CYP3A5 non-expressers and received TAC together with Wuzhi. CYP3A5 genotype (expressers or non-expressers), body weight (40-80 kg), and hematocrit (20 - 40%) were selected as the specific clinical scenarios, and the starting dose of TAC ranged from 1.5 to 4.5 mg when co-administered with Wuzhi. We establish a TAC PPK model comprising Wuzhi as a covariate in renal transplant recipients and recommend an initial dose of TAC when co-administered with Wuzhi, which could provide reference for the individualized regimens of TAC.

Population Pharmacokinetic/Pharmacodynamic Study of Linezolid in Hospital-Acquired Pneumonia Patients with Renal Insufficiency.

The optimal treatment strategy in patients with hospital-acquired pneumonia (HAP) due to Gram-positive bacteria and renal insufficiency remains challenging. The objective of this study was to compare the outcomes of linezolid versus teicoplanin in HAP patients with renal insufficiency and to explore optimal dosage strategy for linezolid. The retrospective study enrolled adult patients treated with intravenous linezolid or teicoplanin at Suzhou Municipal Hospital between July 2018 and August 2023. For the comparative pharmacodynamic study, effectiveness, safety and target attainment of trough concentration (Cmin) for teicoplanin versus linezolid treatment in HAP patients with document Gram-positive bacteria and renal insufficiency were compared. For the population pharmacokinetics (PPK) analyses, linezolid concentrations collected exclusively from HAP patients with renal insufficiency were used and the optimal dosage strategy was investigated using Monte Carlo simulations. Linezolid-treated patients had a higher bacterial eradication rate than teicoplanin-treated patients (88.5% vs 63.4%, P < 0.001). A higher proportion of patients in the linezolid group experienced at least one adverse reaction (42.0% vs 25.0%, P = 0.025). Significantly more supratherapeutic Cmin, less therapeutic Cmin were achieved in the linezolid group (adjusted P < 0.05). A total of 207 linezolid concentrations from 166 patients with renal insufficiency were available for the PPK analysis. Age and creatinine clearance (CrCL) were identified as significant covariates that influenced clearance. Simulations show that 300 mg q12h provide the optimal exposure in patients with a CrCL of 60 or 45 mL/min, and 200 mg q12h was recommended for patients with a CrCL of 30 or 15 mL/min. Linezolid-treated patients with HAP and renal insufficiency had higher bacterial eradication rates, supratherapeutic exposure and adverse reactions than teicoplanin-treated patients. Linezolid dose reduction in patients with renal insufficiency improved the probability of achieving optimal exposure.

Review article: Optimisation of biologic (monoclonal antibody) therapeutic response in inflammatory bowel disease.

There are a plethora of therapeutic options for the management of inflammatory bowel disease (IBD). Despite this, clinical outcomes with standard dosing often fall short of established targets. While efforts centre on developing novel therapies, there is an ongoing need to optimise the use of existing agents. To focus on strategies to optimise response to biologic (monoclonal antibody) therapies in IBD, including use of therapeutic drug monitoring (TDM). An extensive review of the published literature. TDM is a strategy aimed at enhancing the effectiveness of drugs with variable exposure-response relationships by measuring serum concentrations of biologic therapies and detecting neutralising antibodies. Reactive TDM is performed when therapeutic goals have not been achieved. Tumour necrosis factor alpha (TNF) inhibitors are the treatment class most frequently associated with immunogenicity and loss of response. Immunogenicity can be reduced through avoidance of low serum drug concentrations by dose optimisation or use of concomitant immunomodulator therapy. Subtherapeutic dosing in the absence of antidrug antibodies is best managed by dose escalation or dose interval reduction. Persistent neutralising drug antibodies necessitate switching to an alternative therapy. Proactively ensuring adequate serum trough levels might help sustain treatment durability and prevent loss of response. Newer non-TNF inhibitors demonstrate less robust exposure-response relationships, and TDM may not prove as beneficial. In the treat-to-target paradigm of IBD treatment, optimising treatment effect with dose optimisation, which may involve strategies including TDM, increases the likelihood of achieving clinical remission and may accomplish deeper levels of remission beyond symptom control.

A nomogram incorporating linezolid and metabolite concentrations for predicting linezolid induced thrombocytopenia in patients with renal impairment

A nomogram to estimate the risk of linezolid-induced thrombocytopenia in patients with renal impairment is not available. The aim of the study is to develop a nomogram for predicting linezolid-induced thrombocytopenia in patients with renal impairment and to investigate the incremental value of PNU-142300 concentration beyond clinical factors and linezolid trough concentration (Cmin) for risk prediction. Logistic regression was used to identify independent risk factors for linezolid-induced thrombocytopenia in patients with renal impairment and nomograms were established. The performance of the nomograms was assessed in terms of area under the receiver operating characteristic curve (AUROC), net reclassification improvement (NRI), integrated discrimination improvement (IDI) , decision curve analysis (DCA) and calibration. Internal validation and external validation of the nomograms were also performed. Four nomograms were created: nomogram A including total bilirubin, creatinine clearance and concomitant mannitol use; nomogram B containing linezolid Cmin additionally; nomogram C containing total bilirubin, concomitant mannitol use, linezolid Cmin, and PNU142300 concentration; nomogram D including total bilirubin, concomitant mannitol use, and PNU142300 concentration. Nomogram C improved the prediction performance than nomogram A (AUROC 0.881 vs. 0.749; NRI 0.290; IDI 0.226) and nomogram B (AUROC 0.881 vs. 0.812; NRI 0.152; IDI 0.130) in the training cohort. DCA analysis showed that nomogram C yielded a greater net benefit. Compared with nomogram A and nomogram B, nomogram C also showed superior discriminatory efficacy, good calibration and clinical usefulness in the external validation cohort. The nomogram containing PNU-142300 concentration and linezolid Cmin had better predictive capability than that containing linezolid Cmin for predicting linezolid-induced thrombocytopenia in patients with renal impairment.

Crushed posaconazole delayed-release tablets for antifungal prophylaxis and treatment in children.

Therapeutic drug monitoring (TDM) is recommended for posaconazole to achieve target concentrations of ≥0.7 mg/L and ≥1.0 mg/L for prophylaxis and treatment of invasive fungal infection (IFI), respectively. However, target attainment is challenging with the oral suspension, particularly in children. Here, we describe our experience using crushed delayed-release tablet (DRT) in a paediatric cohort, with a focus on TDM. We undertook a retrospective audit of crushed posaconazole DRT administration via enteral feeding tubes (EFTs) for patients aged ≤18 years over 18 months at The Royal Children's Hospital Melbourne who had at least one trough concentration measured at steady state. Details of patient demographics, posaconazole dosing, monitoring and adverse effects were recorded. Twelve patients with a median age of 9 years (range 2 to 14) received posaconazole DRT via EFT for prophylaxis (n = 8) or treatment (n = 4). All children achieved target concentration, with a median dose of 7 mg/kg/day (range 5 to 11) for prophylaxis and 13 mg/kg/day (range 9 to 20) for treatment. The median time to reach therapeutic levels was 7 days (range 5 to 14) for prophylaxis and 20 days (range 15 to 35) for treatment. One child had blockage of their EFT, which was attributed to posaconazole. No other adverse effects were observed. Crushed posaconazole DRT administered via EFT may be used as a method of attaining therapeutic posaconazole concentrations in children for antifungal prophylaxis and treatment.

Abnormally high plasma concentrations of M-4, the active metabolite of edoxaban, at the onset of acute kidney injury in a patient receiving rifampin and clarithromycin: a case report

BackgroundEdoxaban, the only factor Xa inhibitor with active metabolites, is metabolized by carboxylesterase-1 to its main active metabolite, M-4, which is a substrate of organic anion transporting polypeptide 1B1 (OATP1B1) and is excreted in bile and urine. Because the area under the plasma concentration–time curve ratio of M-4 to parent compound is typically less than 10% in healthy subjects, M-4 is generally considered to exhibit negligible antithrombotic activity in patients treated with edoxaban. However, we identified a case in which drug interactions and kidney impairment led to a substantive increase in plasma M-4 concentrations.Case presentationThis case report involved a 68-year-old man with pancreatic cancer who was orally administered edoxaban tablets for prevention of thrombus formation in non-valvular atrial fibrillation, in addition to rifampin and clarithromycin (CAM) for treatment of mycobacterium avium complex lung disease. These medications were temporarily discontinued for a pancreaticoduodenectomy but were resumed 8 days post-surgery (POD8). On POD9, the patient developed acute kidney injury, and the trough concentrations of edoxaban and M-4 were 131.1 ng/mL and 115.8 ng/mL, respectively (M-4 ratio: 88.3%). On POD11, the M-4 trough concentration and M-4 ratio increased to 216.2 ng/mL and 186.2%, respectively. The plasma concentration of coproporphyrin-I, an endogenous biomarker of OATP1B1 activity, increased during this period.ConclusionsThis case suggests that in patients with impaired renal function taking edoxaban, co-administration of carboxylesterase-1 inducers such as rifampin and/or OATP1B1 inhibitors such as rifampin or clarithromycin may increase plasma concentrations of M-4 to clinically non-negligible levels.

Plasma apixaban levels and thrombin generation assay in patients with atrial fibrillation with dose reduction criteria of apixaban

Abstract Background Off-label reduced-dose apixaban is commonly prescribed in patients with atrial fibrillation (AF). However, the pharmacokinetic data of apixaban according to the dosage and label is limited especially in those with dose reduction criteria of apixaban. Purpose We investigated the apixaban plasma concentration (PC) and thrombin generation assay (TGA) parameters across different apixaban dose settings. Methods We enrolled 398 non-valvular AF patients with more than single-dose reduction criteria of apixaban and divided them into three groups: (1) on-label standard dose (single dose-reduction criterion with standard-dose of apixaban 5mg twice daily, n=173); (2) off-label reduced-dose (single dose-reduction criterion with apixaban 2.5mg twice daily, n=61); and (3) on-label reduced-dose (two or more dose-reduction criteria with apixaban 2.5mg twice daily, n=164). Apixaban PC by anti-Xa assay and TGA parameters of these three groups were compared at the trough level. Results The on-label standard dose group showed a higher PC than the on-label reduced dose (124.7 vs. 80.3 ng/mL, p&amp;lt;0.001), and the on-label reduced dose exhibited a higher PC than the off-label reduced dose (80.3 vs. 53.2 ng/mL, p=0.031) (Figure). The TGA parameters displayed a similar pattern of differences, with the on-label standard dose group tends to show the least thrombogenic profiles (Figure). Lower creatinine clearance (CrCl), older age, and female sex were statistically significant predictors for a higher apixaban PC by multivariable regression model (p&amp;lt;0.001, p=0.043, and 0.023, respectively), and CrCl was the most influential variable to dichotomize apixaban PC in all three groups (Figure). Conclusions Off-label reduced-dose apixaban group exhibited significantly lower apixaban level than both on-label standard dose and on-label reduced-dose apixaban groups, suggesting the importance of adhering to current dose-reduction criteria for maintaining appropriate apixaban levels. Caution is particularly advised in off-label under-dosing for patients with high creatinine clearance. Further investigation into the impact of off-label under-dosing on clinical outcomes is essential to guide optimal therapeutic strategies.

Transition of patients with familial chylomicronaemia syndrome from volanesorsen to olezarsen: safety and pharmacokinetic results

Abstract Background Familial chylomicronaemia syndrome (FCS) is a rare genetic disorder of lipoprotein lipase deficiency resulting in severe hypertriglyceridaemia and pancreatitis risk. Volanesorsen is a weekly-injected antisense oligonucleotide (ASO) designed to degrade APOC3 mRNA that is approved as an adjunct to diet to treat FCS in the EU, UK, and Brazil. Olezarsen is an investigational monthly-injected ASO-GalNAC3 conjugate also designed to degrade APOC3 mRNA, but directed to hepatocytes, resulting in more potency and less systemic exposure and making it a potential alternative to volanesorsen for FCS. Purpose This interim analysis of an open-label phase 3 trial evaluated olezarsen safety and pharmacokinetics in patients (pts) with FCS previously treated with volanesorsen. Methods Adults with FCS with prior volanesorsen treatment, or actively participating in an expanded access programme (US and Canada), started olezarsen 80 mg by subcutaneous injection every 4 weeks after a minimum washout of 6 weeks. Historical volanesorsen laboratory and safety data were unavailable. The primary objective was to assess safety from changes vs baseline in platelet count, liver enzymes, and renal function; bleeding events; and adverse events. Pharmacokinetic measurements included plasma volanesorsen and olezarsen concentrations. Immunogenicity was assessed by measuring anti-drug antibodies (Abs). Results Of 24 pts enrolled, the majority were female (n=13; 54.2%) and White (n=21; 87.5%), with mean age of 49.1 years; 20 (83.3%) had genetically and 4 (16.7%) clinically validated FCS, all had history of acute pancreatitis (or symptoms suggestive of pancreatitis requiring hospitalisation or emergency room/urgent care visit; mean, 3.4 episodes within 5 years) and 5 (20.8%) of thrombocytopaenia. Time since last volanesorsen dose was 42—1118 days. Baseline fasting triglyceride (median [interquartile range (IQR)], 18.6 [9.6,34.0] mmol/L [1648 (852,3007) mg/dL]; mean [standard deviation (SD)], 25.5 [20.5] mmol/L [2256 (1812) mg/dL]) and apolipoprotein C-III (median [IQR], 0.2 [0.1,0.4] g/L [16.1 (12.4,39.0) mg/dL]; mean [SD], 0.3 [0.2] g/L [25.9 (19.5) mg/dL]) levels were elevated. During a mean (SD) of 329 (95) days of olezarsen 80 mg treatment, no pts experienced hepatic failure, renal impairment, major bleeding events, or platelet count below the prespecified threshold of 50,000 mm³ (Table 1). Olezarsen levels at trough were elevated during the first 3 months, mainly due to residual volanesorsen levels in pts with washout &amp;lt;90 days (Figure 1). Eleven (45.8%) pts had treatment-emergent anti-olezarsen Abs, of whom 5 (20.8%) had anti-volanesorsen Abs, with no impact on safety or efficacy; pts with vs without anti-drug Abs had higher olezarsen trough levels (mean, 4.4–7.8 ng/mL vs 1.1 ng/mL). Conclusions In this interim analysis, olezarsen was safe and well tolerated in pts with FCS previously treated with volanesorsen after a minimum washout of 6 weeks.

Geometric optimization to improve the performance of a new design of concentration‐based solar distiller using particle swarm optimization algorithm

AbstractSolar distillers are one of the oldest and simplest technologies for desalinating salt water using solar energy. The main problem is the low freshwater production compared to the amount of energy input from the sun. To overcome this problem, a solar distiller was developed using a parabolic trough concentrator to increase the freshwater yield. The geometry optimization of various parameters of the developed system was also studied using the particle swarm optimization (PSO) algorithm to obtain the optimal design and give the improved freshwater yield. The simulation is carried out based on the algorithm using the climatic condition data of Rabat City, Morocco. Numerical resolution of the energy balance equations was performed using MATLAB code. In terms of flexibility, speed, and global convergence, this method's final results were satisfactory. The maximum optimized freshwater yield using the PSO approach is 12.83 kg/m2 and the maximum optimized energy and exergy efficiency were about 204.7% and 34.3%, respectively. Furthermore, the results showed that the absorber basin accounts for the highest exergy destruction, 88.7% of the total optimized exergy destruction was found from exergy analysis.

Identification of vancomycin exposure target in neonates: how much is enough?

Vancomycin is commonly used in neonates with the same pharmacokinetics/pharmacodynamics (PK/PD) target as adults. However, no evidence supports this practice, and the association between trough concentrations and treatment outcomes has been widely questioned. This study aimed to identify the optimal PK/PD predictor and assess the correlation between AUC/MIC, trough concentration and the vancomycin efficacy in neonates. This study retrospectively collected neonates who used vancomycin and constructed a population pharmacokinetic (PPK) model to estimate the AUC. Logistic analyses were used to identify the variables related to efficacy. Classification and regression tree analysis was used to explore thresholds. The correlation between trough concentration and AUC/MIC on the first day was analysed using a linear regression model. PPK modelling involved 131 neonates. Postmenstrual age and current weight were included in the covariate analysis. Forty-eight patients were included in the efficacy analysis, 13 of whom were infected with MRSA. The best-performance PK/PD target for efficacy was AUC0-24 h/MIC ≥ 331. The trough concentration was correlated with AUC0-24 h/MIC (r2 = 0.32), but individual differences existed. AUC0-24 h/MIC ranged up to 2.5-fold for a given trough concentration. AUC0-24 h/MIC ≥ 331 was the optimal target of vancomycin efficacy in neonates. The trough concentration was not a reliable predictor of efficacy and AUC0-24 h/MIC. AUC-guided dosage adjustments are more valuable in clinical applications.

Safety of the reduced fixed dose of mycophenolate mofetil confirmed via therapeutic drug monitoring in de novo kidney transplant recipients.

Mycophenolate mofetil (MMF) is usually prescribed with a reduced fixed dose in Asian kidney transplant recipients (KTRs). However, the clinical efficacy and safety of the fixed dose have not yet been investigated via therapeutic drug monitoring. We evaluated whether reduced fixed-dose MMF is an optimal dosing strategy to achieve the therapeutic target of mycophenolic acid (MPA) exposure in Korean KTRs. This open-label, prospective study enrolled 50 de novo KTRs prescribed with tacrolimus, corticosteroid, and fixed-dose MMF (1.0-1.5 g/day). The trough level (C0) and area under the curve (AUC0-12 hr) of MPA were measured at 1 and 24 weeks after kidney transplantation (KT). The relationship of body weight (BW)-adjusted MMF dose with MPA C0 and MPA AUC0-12 hr was assessed using linear regression analysis. The initial fixed dose of MMF of 1.44 ± 0.16 g/day was adjusted in 24 patients (48.0%) and then reduced to a mean dose of 1.19 ± 0.31 g/day at 24 weeks after KT. Most patients (≥84.0%) attained the minimum required MPA C0 of 1.0 μg/mL and MPA AUC0-12 hr of 30 μg × hr/mL at 1 and 24 weeks. The BW-adjusted MMF dose demonstrated significant positive correlations with MPA C0 and MPA AUC0-12 hr at 1 and 24 weeks after KT. Moreover, 14 patients (28.0%) reported MPA-related adverse events that were predictable based on MPA AUC0-12 hr (cutoff level, 46.4 μg × hr/mL). The current reduced fixed-dose MMF strategy can help achieve the therapeutic target of MPA exposure in tacrolimus-treated Korean KTRs during the early posttransplant period.

Gentamicin Pharmacokinetics in Neonates Undergoing Therapeutic Hypothermia for Hypoxic Ischemic Encephalopathy.

The purpose of this study was to review the pharmacokinetic profile of gentamicin among neonates with hypoxic ischemic encephalopathy (HIE) undergoing therapeutic hypothermia (TH) treatment. This was a retrospective study of neonates with HIE undergoing TH in the neonatal intensive care unit who received gentamicin between 2009 and 2014. Demographic information, diagnoses, laboratory test results, and medication administration and monitoring information were collected, and data were analyzed using SciPy. A total of 57 neonates were analyzed. The median birth weight was 3.25 kg (interquartile range [IQR] 2.8-3.68), and median gestational age was 39 weeks (IQR 38-40). An elevated gentamicin trough level (defined as > 2 mg/L) was observed in 61% (35/57) of neonates. Half of the neonates (49%) had multiple gentamicin trough levels obtained, and 4% of the neonates were switched to an alternate agent. There was a significant difference in the number of dosing interval changes in neonates with elevated gentamicin trough levels compared with those with therapeutic gentamicin trough levels (P < 0.001). Of the neonates with elevated gentamicin trough levels, 14% (5/35) failed their hearing screen (P = 0.389). Neonates with HIE undergoing TH may have an altered pharmacokinetic profile, requiring multiple blood draws so medication levels can be monitored and doses adjusted.Traditional gentamicin dosing regimens may not be ideal for this patient population, and further guidance is required for alternative treatment regimens.

Voriconazole trough levels after switching from an intravenous to oral formulation in a patient with short bowel syndrome.

Voriconazole trough levels after switching from an intravenous to oral formulation in a patient with short bowel syndrome.

Comparison of Vancomycin AUC24 Calculation Methods for Neonates and Infants.

For neonates and infants receiving intermittent vancomycin infusions, the area under the concentration-timecurve during 24 h (AUC24) is often estimated with Bayesian forecasting using one or more measured vancomycin concentrations. When practical peak and trough concentrations are measured at steady state, AUC24 can also be calculated with first-order steady-state equations for a one-compartment model (Sawchuk-Zaske method), but previously this method has been applied only for adults. The objective of this studywas to compare AUC24 values obtained with the Sawchuk-Zaske method and two Bayesian models. AUC24 values were estimated retrospectively for 18 neonates and infants with steady-state peak and trough concentrations using traditional compartmental analysis with a one-compartment model (reference method), the Sawchuk-Zaske method, and Bayesian forecasting with two previously published models. In Bayesian forecasting, both original and modified residual error models were used. In the modified models, the residual error was reduced by setting the additive residual error to zero and the proportional error to 15%. AUC24 estimates obtained with the Sawchuk-Zaske method differed -2.7 to 0.9% from the reference method. When both peak and trough concentrations were used in Bayesian forecasting, 61% and 33% of AUC24 estimates obtained with two original models differed less than 15% from the reference method, and these fractions increased to 83% and 72% with the modified models, respectively. When practical peak and trough concentrations are measured at steady state, the simple Sawchuk-Zaske method is very useful for AUC24 estimation in neonates and infants. In Bayesian forecasting, the reduced residual error model can be used to improve the model fit.

Therapeutic drug monitoring and safety of voriconazole in patients with liver dysfunction.

This study aims to describe the distribution characteristics of voriconazole (VRC) plasma trough concentrations (Ctrough) in patients with liver dysfunction, identify factors influencing VRC Ctrough, and provide recommendations for the use of VRC in this population. We retrospectively collected medical records of hospitalized patients with liver dysfunction who used VRC and underwent therapeutic drug monitoring (TDM) at the First Hospital of Changsha. The severity of liver dysfunction was assessed by the Child-Pugh (CP) score. Multiple linear regression was employed to explore factors affecting VRC Ctrough in these patients. A total of 147 Ctrough from 102 patients with liver dysfunction were analyzed. Patients were categorized into a control group (n = 40), CP-A (n = 39), CP-B (n = 11), and CP-C group (n = 12). The initial probability of target attainment of Ctrough was 70.6%, with 6.9% of patients obtaining subtherapeutic Ctrough and 22.5% obtaining supertherapeutic Ctrough. The initial Ctrough in CP-A and B were 5.05 (0.64-9.57) mg/L and 5.37 (0.26-10.01) mg/L, respectively, significantly higher than the control group (P = 0.021 and P = 0.010). The proportion of VRC Ctrough of >5.5 mg/L in CP-A and B was 33.3% and 45.5%, respectively. Multiple linear regression analysis revealed that factors such as age ≥70 years, CP class, C-reactive protein (CRP), and direct bilirubin were significantly related to the initial VRC Ctrough. Among all measurements, patients with severe inflammation (CRP >100 mg/L), aged ≥70 years, and albumin levels of <30 or <25 g/L had significantly higher VRC Ctrough. The treatment success rate of VRC was 69.6% (71 of 102), and the rate of VRC-related adverse drug reactions was 29.4% (30 of 102). The recommended half-maintenance dose may lead to elevated VRC Ctrough in patients with CP-A and CP-B. TDM is essential for patients with advanced age, severe infections, or hypoalbuminemia to prevent excessive VRC trough levels.

The Influence of High Body Mass Index (BMI > 35 kg/m2) on Apixaban Plasma Concentration in Patients with Atrial Fibrillation.

Apixaban, a direct oral anticoagulant is administered for stroke prevention in atrial fibrillation patients. Dosing adjustment is guided by renal function, age, and body weight. However, no data exist on its pharmacokinetics in patients with a body mass index (BMI) ≥ 35 kg/m2. The aim was to investigate the effects of BMI ≥35 kg/m2 on trough plasma concentrations of apixaban in patients with atrial fibrillation. This prospective study compared steady-state trough concentrations of apixaban in patients with a BMI ≥35 kg/m2 and patients with a BMI <35 kg/m2. Sixty patients were included. In patients receiving 5 mg apixaban twice daily, the median trough plasma concentration was 29% lower in patients with a BMI ≥35 kg/m2 than in those with a BMI <35 kg/m2 (148.9 ng/ml, interquartile range [IQR] 94.5-205.6, compared to 209.1 ng/ml, IQR 167-266.8 ng/ml, respectively; P = 0.044). However, median trough concentrations fell within the manufacturer's predicted range for effective steady-state apixaban exposure. A similar trend was observed with 2.5 mg apixaban twice daily, although statistical significance was not reached. Multivariate analysis revealed no correlation between BMI values and trough concentrations. BMI ≥35 kg/m2 patients exhibited lower apixaban trough concentrations, while remaining within the manufacturer's established range for effective steady-state apixaban, suggesting that dose adjustment is unnecessary for this specific patient group.

Effectiveness of switching to subcutaneous infliximab in inflammatory bowel disease patients with inadequate biochemical response during intravenous administration

Infliximab (IFX) has transformed the management of inflammatory bowel diseases (IBD). While intravenous (IV) IFX has been effective, a subcutaneous (SC) formulation offers advantages in convenience and cost. However, there is lack of evidence regarding the transition from IV to SC-IFX, especially for patients with inadequate responses. This study investigates the effectiveness of switching from IV to SC-IFX in patients with inadequate responses during IV maintenance therapy. A retrospective study enrolled IBD patients who transitioned to SC-IFX after demonstrating inadequate responses during IV maintenance therapy. The study collected data of demographics of patients and dose and therapies administered prior to the IV-IFX. Primary outcomes included improvements in C-reactive protein (CRP) or fecal calprotectin (FC) levels. This study evaluated the trough levels and its differences between pre- and post-switching. Among 44 patients included, 10 exhibited CRP elevation before the switch, with 6 showing normalization post-switch. Similarly, 42 patients had elevated FC levels pre-switch, with 26 experiencing reductions post-switch. Trough levels increased after the switch. However, there were no significant differences between responders and non-responders. This study is the first study to investigate the transition therapy of IV to SC-IFX in patients with inadequate response. This suggests that SC-IFX could be a viable alternative in the management of IBD. However, further research is necessary to evaluate its efficacy in a larger population of patients who exhibit inadequate responses during IV-IFX maintenance therapy.

Advanced optimization of elastic sheets for solar parabolic trough concentrators: integrating particle swarm optimization and genetic algorithms

Abstract The fabrication of solar parabolic trough concentrators using flat elastic sheets presents a straightforward and cost-effective method. This paper introduces an optimization technique centered on stiffness adjustment, harnessing elastic buckling to attain precise parabolic shapes in these concentrators. Through an enhanced Particle Swarm Optimization-Genetic Algorithm (PSO-GA), strategically punched holes are optimized on the flat sheet, allowing for the attainment of perfect parabolic shapes by controlling the chord length with a positional rod or cable. The efficacy of this approach is showcased not only through interactive finite element analysis and ray tracing software simulations but also via experimental sunlight concentration. A geometric concentration ratio of up to 145.16 is achieved, underscoring the effectiveness of this innovative concept. This approach facilitates the simple fabrication and transportation of flat mirror elements to field sites, where they can be assembled into parabolic trough concentrators, offering potential cost reductions and highly efficient solar energy solutions.