Trough Levels Research Articles

Serum concentration threshold and risk factors of tigecycline-induced hypofibrinogenaemia in critically ill patients

Abstract Objectives Hypofibrinogenaemia is a serious adverse reaction associated with tigecycline (TGC) therapy and may lead to the discontinuation of the treatment. This study aimed to explore the relevant factors of TGC-induced hypofibrinogenaemia and determine the thresholds of serum concentration as a predictive indicator of TGC-induced hypofibrinogenaemia. Methods A retrospective single-centre study was conducted on patients with severe infection who were treated with TGC. Clinical data and serum concentration parameters were extracted from the electronic medical records of these patients. Patients were divided into the hypofibrinogenaemia group (< 2.0 g/L) and the normal fibrinogen group (≥ 2.0 g/L) in order to evaluate risk factors associated with TGC-induced hypofibrinogenaemia. Logistic regression analysis and receiver operating characteristic curves were utilized to identify the risk factors associated with TGC-induced hypofibrinogenaemia and to establish plasma concentration thresholds as predictive indicators. Results A total of 114 patients were enrolled in this study, with 59.6% experiencing hypofibrinogenaemia. The multivariate regression analysis indicated that baseline fibrinogen level, trough concentration (Cmin), peak concentration (Cmax), the concentration at 6 h after the dosing (C6h) and the area under the concentration–time curve over a 24-h period (AUC0–24) were significantly associated with hypofibrinogenaemia (P < 0.05). Furthermore, it was found that AUC0–24 is the optimal predictor of TGC-induced hypofibrinogenaemia. The optimal cut-off for the AUC0–24 of TGC in ICU patients was determined to be 17.03 mg h/L. Conclusions TGC exposure is highly predictive of TGC-induced hypofibrinogenaemia. We recommend closely monitoring plasma concentrations of TGC in patients to ensure patient efficacy and safety.

Therapeutic drug monitoring of posaconazole delayed-release tablets and injections in pediatric patients.

This study aimed to investigate the dose and trough concentration (Cmin) of posaconazole delayed-release tablets and injections, and their correlation with efficacy and safety in pediatric patients. Patients younger than 18 years old received posaconazole delayed-release tablets or injections for prophylaxis or treatment of invasive fungal disease (IFD). Blood samples were collected to determine the plasma Cmins, and dose regimen adjustments were made if necessary. Clinical data were collected. A total of 210 Cmins of 113 pediatric patients were detected. The median Cmins were 1.0 and 1.3 mg/L for tablets and injections, respectively (P < 0.05). The median doses required to achieve the target Cmin were about 6.0 mg/kg of body weight/day, and no statistical difference was observed between different age groups, formulations, or indications (P > 0.05). Concomitant treatment of tacrolimus and diarrhea were found to affect Cmins of tablets, while age, gender, and BMI were found to be correlated with Cmins of injections. IFD breakthrough occurred in 9.2% of patients with a median Cmins of 0.74 mg/L for prophylaxis, and infection progression occurred in 43.2% of patients with a median Cmins of 0.97 mg/L for treatment, respectively. Transaminitis was the most common adverse event. Posaconazole delayed-release tablets and injections are safe for prophylaxis and treatment of IFD in pediatric patients. An empirical initial dose of 6.0 mg/kg of body weight/day is appropriate for prophylaxis, while a higher dose should be required for the treatment of IFD. It is necessary to adjust the dose regimen according to the results of therapeutic drug monitoring.This study is registered with chictr.gov.cn under identifier ChiCTR2300070008.

Dose, exposure, and treatment regimen of intravenous immunoglobulin G in multifocal motor neuropathy

IntroductionIntravenous immunoglobulin (IVIG) is the only approved treatment for multifocal motor neuropathy (MMN), a rare, chronic, immune-mediated demyelinating neuropathy. There is a significant gap in understanding of the role of serum immunoglobulin G (IgG) levels in the efficacy of IVIG in affected patients. We aimed to characterize the interplay between dose and exposure of IVIG and the effects of patient factors on individual variabilities.MethodsSerum IgG trough concentration data from a phase 3, randomized, double-blind, placebo-controlled, crossover trial of IVIG 10% in 44 patients with MMN (NCT00666263) were analyzed using fit-for-purpose population PK modeling. Patient factors were tested as covariates, and IgG PK profiles following various dosing regimens were simulated.ResultsSerum IgG levels, with significant inter-patient variability, correlated with dose and treatment interruptions at the individual patient level. Simulated data for various dosing regimens (0.4–2 g/kg once every 1–4 weeks [Q1–4W]) revealed that more frequent dosing provided more stable IgG levels than less frequent dosing, and dose splitting over multiple days had no significant effects on PK.DiscussionIn patients with MMN, stable dosing and consistent serum IgG levels are crucial to avoid negative responses owing to treatment interruptions. Dosing intervals more frequent than Q4W may alleviate periodic symptom deterioration. Dose splitting potentially offers flexibility for patients requiring large volumes of IVIG without negatively affecting serum IgG PK, while maintaining treatment efficacy. Variability in serum IgG levels between patients suggests that individualizing IVIG treatment regimens and target IgG levels may play a key role in managing MMN.

Long-term renal outcomes of children with cancers treated with platinum-based chemotherapy: A retrospective chart analysis.

Platinum-based chemotherapy is a mainstay of treatment for many childhood cancers but is associated with acute nephrotoxicity and long-term ototoxicity. There is emerging evidence of long-term renal complications. This study aimed to assess the prevalence of chronic kidney disease (CKD) in children treated with platinum chemotherapy (cisplatin and carboplatin) and identify potential risk factors for the development of CKD. We conducted a retrospective review of children diagnosed with hepatoblastoma, osteosarcoma, neuroblastoma, or medulloblastoma who received platinum chemotherapy over a 16 year timeframe. Patients were excluded if they did not have at least 3 years follow up data, died within 3 years of platinum chemotherapy, or if they relapsed. Clinical data were collected at baseline (first dose), 1 year, and at most recent follow up. Of 328 treated patients, 147 met the inclusion criteria and were followed for a mean of 8.1 years (range 3-15.7 years). The median age at first dose was 3.7 years (IQR 1.7-9.6 years). CKD ≥grade 2 was present in 53(36%) at last follow up and 15(10%) had tubular dysfunction. A history of acute kidney injury at any time during treatment was associated with CKD (OR 3.12 CI 1.07-9.12, p =0.04). On multivariable analysis older age at platinum therapy (OR 1.2, CI 1.1-1.4, p = 0.004) and a high aminoglycoside or vancomycin trough level (OR 4.3, CI 1.9-9.7, p<0.001) were risk factors for CKD. The high rate of CKD in children treated with platinum chemotherapy warrants long-term follow-up and screening for progressive disease.

Therapeutic drug monitoring of tenofovir disoproxil and emtricitabine in oral HIV pre-exposure prophylaxis (PrEP) users who have undergone gastrointestinal surgery.

Oral HIV pre-exposure prophylaxis (PrEP) is highly effective in preventing HIV, but its efficacy depends on adequate absorption of drug, which may decrease following gastrointestinal surgery. Clinicians across eight Genito-urinary Medicine clinics in the United Kingdom submitted data on PrEP users with history of gastrointestinal surgery who were referred to a national complex PrEP multi-disciplinary team between June 2021 and April 2023. Anonymised data were submitted on demographics, surgical history, PrEP regimen, and results of therapeutic drug monitoring (TDM) and HIV screening tests. Descriptive analyses were performed in SPSS version 29. Nine cases described cis-gender men-who-have-sex-with-men (MSM) with median age of 47.4 years (IQR = 43 - 56.5) taking tenofovir disoproxil (TDF)/emtricitabine (FTC) daily (n = 8) or event-based (n = 1) as PrEP. Median time between PrEP initiation and TDM was 53 days (IQR = 8.5-1705). The mean (±SD) trough concentration of tenofovir (TFV) and FTC were 90.2 ± 27.7ng/mL and 76.0 ± 45.9ng/mL, respectively. All patients had a negative HIV test at follow-up. Plasma trough concentrations of TFV observed in our cohort taking TDF/FTC were above the expected concentrations associated with PrEP efficacy as previously described in the literature, suggesting that PrEP can be safely given in this population, with TDM used for reassurance.

Steady-State Drug Exposure of Repeated IV Bolus Administration for a One Compartment Pharmacokinetic Model with Sigmoidal Hill Elimination.

Drugs exhibiting nonlinear pharmacokinetics hold significant importance in drug research and development. However, evaluating drug exposure accurately is challenging with the current formulae established for linear pharmacokinetics. This article aims to investigate the steady-state drug exposure for a one-compartment pharmacokinetic (PK) model with sigmoidal Hill elimination, focusing on three key topics: the comparison between steady-state drug exposure of repeated intravenous (IV) bolus ( ) and total drug exposure after a single IV bolus ( ); the evolution of steady-state drug concentration with varying dosing frequencies; and the control of drug pharmacokinetics in multiple-dose therapeutic scenarios. For the first topic, we established conditions for the existence of , derived an explicit formula for its calculation, and compared it with . For the second, we identified the trending properties of steady-state average and trough concentrations concerning dosing frequency. For the third, we developed formulae to compute dose and dosing time for both regular and irregular dosing scenarios. As an example, our findings were applied to a real drug model of progesterone used in lactating dairy cows. In conclusion, these results provide a theoretical foundation for designing rational dosage regimens and conducting therapeutic trials.

Early acute kidney injury after tacrolimus administration in heart transplant recipients receiving basiliximab induction therapy.

In this study, we aimed to analyze the association among the timing of tacrolimus initiation, time required to reach the target blood concentration, and early acute kidney injury (AKI) after tacrolimus administration in heart transplant recipients who received basiliximab induction therapy. 88 patients treated with tacrolimus-based immunosuppressive therapy were retrospectively reviewed. Induction therapy was administered to 52 patients. AKI was evaluated within 7 days of tacrolimus administration. The rate of increase in tacrolimus trough concentration to the target trough concentration of 10 µg/mL early after its administration was set to be similar in the basiliximab induction and non-induction group; 8 and 2 patients developed AKI in the induction and non-induction group, respectively. In the induction group, there was no significant difference in the timing of tacrolimus initiation and the time required to reach the target concentration between patients who developed and did not develop AKI. In contrast, the cumulative incidence of AKI was significantly different between patients with an estimated glomerular filtration rate below and those with an estimated glomerular filtration rate above 43 mL/min/1.73m2 at the start of tacrolimus administration (37.5% and 11.4%, respectively; p=0.045). In patients receiving basiliximab induction therapy, the timing of tacrolimus initiation and the time to reach the target concentration are unlikely to be associated with early AKI after tacrolimus administration. However, the recovery of sufficient renal function after heart transplantation is important for determining the start time of tacrolimus.

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.

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.