Hypoalbuminemia and Pharmacokinetics: When the Misunderstanding of a Fundamental Concept Leads to Repeated Errors over Decades

Association of procalcitonin with voriconazole concentrations: a retrospective cohort study

Inflammation is a potential risk factor of voriconazole (VCZ) overdose, procalcitonin (PCT) is reported to act as a diagnostic marker for bacterial infections. However, the association of PCT with VCZ trough serum concentrations (VCZ-Cmin) is not fully clear. Our study aims to investigate the associations between PCT and VCZ-Cmin. In this retrospective cohort study, we collected the clinical data of 147 patients who received VCZ and monitored the VCZ concentration of them in our hospital from August 2017 to August 2021. All patients underwent routine clinical examinations on the day or the day before VCZ administration. General information and clinical symptoms of these patients were recorded. Multivariate liner analysis showed that PCT was significantly associated with VCZ-Cmin (p < 0.001). Overall, it was shown that VCZ-Cmin was significantly increased by 0.32 µg/mL for each fold increment in PCT in crude model. In the minor adjusted model (Model 1, adjustment for sex, age, albumin, direct bi1irubin, WBC) and fully adjusted model (Model 2, adjustment for sex, age, albumin, direct bilirubin, WBC, AST and ALT), VCZ-Cmin was significantly increased by 0.23 µg/mL and 0.21 µg/mL, respectively, for each fold increment in PCT. In conclusion, this research reveals the correlation between PCT and VCZ-Cmin, indicating that PCT has the potential to serve as a valuable biomarker for drug monitoring in the treatment of VCZ.

Pharmacokinetics of S1P receptor modulators in the treatment of ulcerative colitis

INTRODUCTION

Ulcerative colitis is a chronic inflammatory bowel disease, affecting the colorectal mucosae, with a relapsing-remitting course, characterized by the trafficking and gathering of lymphocytes in the inflammatory intestinal mucosa. Sphingosine-1-phosphate (S1P) receptor modulators preventing lymphocytes egress from lymphoid tissues to the active inflammation site is an alternative therapeutic option in this condition.

AREA COVERED

We carried out a comprehensive review of the literature available on Medline, Scopus and Embase regarding the pharmacokinetics of S1P receptor modulators. For each compound, we reviewed the mechanism of action, pharmacokinetic data and efficacy and safety data from phase 3 studies and real-life studies when available.

EXPERT OPINION

S1P receptor modulators, including ozanimod and etrasimod (both currently on the market) as well as VTX002 (under development), are a new class of drugs for the treatment of moderate to severe ulcerative colitis, inducing and maintaining the remission. Due to its pharmacokinetic features, this class of drugs has certain advantages such as an oral administration, a short half-life, a high volume of distribution, and no immunogenicity. On the other hand, there are risks of cardiological and ophthalmological side-effects, as well as drug-drug interactions risk, that require special attention from the healthcare providers.

Age-Related Changes in Vancomycin Protein Binding: Is It Time to Take It Seriously?

BACKGROUND

Vancomycin (VAN) protein binding in plasma is influenced by illness and age; hence, doses titrated according to total concentrations are fraught. In this study, model-estimated free VAN concentrations (EFVC) were compared with assumed free VAN concentrations (AFVC) in neonates, children, and adults in the intensive care unit and those on dialysis.

METHODS

Patient cohorts were identified from the hospital database. Demographics, clinical characteristics, total VAN concentrations, and laboratory variables were obtained from electronic health records. EFVC was derived from 6 models identified in the literature. For all models, total VAN concentration was the most important predictor; other predictors included albumin, total protein, and dialysis status. The AFVC was calculated as 50% of the total concentration (ie, assumption of 50% bound).

RESULTS

Differences between EFVC and AFVC in adults were insignificant; however, differences in pediatric intensive care unit patients, according to 2 different models, were significant: mean ± SD = 4.1 ± 1.58 mg/L and 4.7 ± 2.46 mg/L ( P < 0.001); the percentages within the free VAN trough range = 30.4% versus 55.1% and 30% versus 55.1%; and the supratherapeutic percentages = 65.2% versus 31.9% and 66.7% versus 31.9%, respectively. In neonates, the difference between EFVC and AFVC was mean ± SD = 6.9 ± 1.95 mg/L ( P < 0.001); the percentages within the free VAN trough range for continuous and intermediate dosing were 0% versus 81.3% and 14.3% versus 71.4%, and the supratherapeutic percentages were 100% versus 6.25% and 71.4% versus 0%, respectively.

CONCLUSIONS

The fraction of free unbound VAN is higher in sick children and neonates than in adults. Therefore, total VAN concentrations do not correlate with the pharmacologically active free VAN concentrations in the same manner as in adults. Adjusting VAN doses in neonates and children to target the same total VAN concentration as the recommended therapeutic range for adults may result in toxicfree concentrations.

Retrospective analysis of a flucloxacillin oral absorption test in patients requiring flucloxacillin therapy: results and determination of factors associated with adequate absorption

OBJECTIVES

Flucloxacillin has the most narrow spectrum to treat staphylococcal infections, but has a large variability in bioavailability which hampers its intravenous (iv) to oral switch. To identify patients with adequate absorption, the use of an oral absorption test (OAT) measuring total plasma concentrations of flucloxacillin before and after an oral dose of 1 gram flucloxacillin, was previously published. The current pilot study aims to evaluate the fraction of patients with adequate absorption using a similar OAT; to assess the therapeutic consequences and to identify potential factors associated with adequate absorption.

METHODS

Demographic data of adult patients treated with iv flucloxacillin and requiring prolonged therapy were collected retrospectively between May 2020 and November 2021 at Ghent University Hospital. A previously published OAT protocol was used, with addition of a protocol for intermittent dosing of iv flucloxacillin. Adequate absorption was defined as an increase in plasma concentration of at least 10 mg/L.

RESULTS

The flucloxacillin OAT was performed in 99 patients, of which 62% were men, with a median age of 58 years and 95% received intermittent dosing of iv flucloxacillin. Of the 99 patients, 55% had a result indicating an adequate absorption and 49% of all patients were switched to oral flucloxacillin afterwards. Inadequate absorption was found to be associated with higher Body Mass Index and higher flucloxacillin baseline concentration, while co-administration of acetylsalicylic acid was associated with an adequate absorption.

CONCLUSIONS

Based on the OAT, 49% of all patients were switched to oral flucloxacillin instead of broader-spectrum anti-staphylococcal antibiotics. This implicates that an OAT could be a valuable antimicrobial stewardship measure by restricting the use of broad-spectrum antibiotics. For each of the associations found, a hypothesis was formulated about the underlying reason or mechanism; these should be confirmed in future studies with prospective and multicentric design.

Treatment of Acute Kidney Injury: A Review of Current Approaches and Emerging Innovations

Acute kidney injury (AKI) is a complex and life-threatening condition with multifactorial etiologies, ranging from ischemic injury to nephrotoxic exposures. Management is founded on treating the underlying cause of AKI, but supportive care-via fluid management, vasopressor therapy, kidney replacement therapy (KRT), and more-is also crucial. Blood pressure targets are often higher in AKI, and these can be achieved with fluids and vasopressors, some of which may be more kidney-protective than others. Initiation of KRT is controversial, and studies have not consistently demonstrated any benefit to early start dialysis. There are no targeted pharmacotherapies for AKI itself, but some do exist for complications of AKI; additionally, medications become a key aspect of AKI management because changes in renal function and dialysis support can lead to issues with both toxicities and underdosing. This review will cover existing literature on these and other aspects of AKI treatment. Additionally, this review aims to identify gaps and challenges and to offer recommendations for future research and clinical practice.

Interspecies variability in protein binding of antibiotics basis for translational PK/PD studies-a case study using cefazolin

For antimicrobial agents in particular, plasma protein binding (PPB) plays a pivotal role in deciphering key properties of drug candidates. Animal models are generally used in the preclinical development of new drugs to predict their effects in humans using translational pharmacokinetics/pharmacodynamics (PK/PD). Thus, we compared the protein binding (PB) of cefazolin as well as bacterial growth under various conditions in vitro. The PB extent of cefazolin was studied in human, bovine, and rat plasmas at different antibiotic concentrations in buffer and media containing 20-70% plasma or pure plasma using ultrafiltration (UF) and equilibrium dialysis (ED). Moreover, bacterial growth and time-kill assays were performed in Mueller Hinton Broth (MHB) containing various plasma percentages. The pattern for cefazolin binding to plasma proteins was found to be similar for both UF and ED. There was a significant decrease in cefazolin binding to bovine plasma compared to human plasma, whereas the pattern in rat plasma was more consistent with that in human plasma. Our growth curve analysis revealed considerable growth inhibition of Escherichia coli at 70% bovine or rat plasma compared with 70% human plasma or pure MHB. As expected, our experiments with cefazolin at low concentrations showed that E. coli grew slightly better in 20% human and rat plasma compared to MHB, most probably due to cefazolin binding to proteins in the plasma. Based on the example of cefazolin, our study highlights the interspecies differences of PB with potential impact on PK/PD. These findings should be considered before preclinical PK/PD data can be extrapolated to human patients.

Impact of hypoalbuminemia on clinical outcomes among patients with obesity treated with ceftriaxone

The use of ceftriaxone, a highly protein-bound drug, in the setting of hypoalbuminemia may result in suboptimal drug exposure. Patients with obesity also exhibit higher absolute drug clearance. We aimed to evaluate the impact of hypoalbuminemia on clinical success among hospitalized adults with obesity who were treated with ceftriaxone. This retrospective review included adult inpatients with weight >100 kg or body mass index >40 kg/m2 who received ceftriaxone 2 g intravenously every 12 hours for at least 72 hours. The primary outcome was clinical success, a composite of clinical cure and microbiologic cure. Secondary outcomes included clinical cure, microbiologic cure, length of stay, ICU length of stay, mortality, 30-day readmission, and adverse events. In all, 137 patients were included, 34 of whom had a serum albumin of ≤2.5 g/dL. In a propensity-score-weighted analysis, clinical success was significantly more common among those without hypoalbuminemia (91.2%) as compared to those with hypoalbuminemia (77.8%) (P = 0.038). Death within 30 days (13.7% vs 0%, P < 0.001) and 30-day readmission (31.6% vs 12.0%, P = 0.008) were more common in the hypoalbuminemia group. In a univariate analysis, serum albumin and indication for ceftriaxone use were found to be predictors of clinical success. Hypoalbuminemia was associated with a lower rate of clinical success among patients with obesity who were treated with ceftriaxone 2 g every 12 hours.

Forgettable in the care of liver cirrhosis: the unseen culprits of progression from bad to worse

Patients with liver cirrhosis constitute a critically ill and unique population, and their stability relies on a well-coordinated multidisciplinary team with a carefully structured plan. Overlooking any aspect of this plan can expedite disease progression, leading to severe complications. The lack of disease-specific nutritional guidance, the prevalent sedentary lifestyle among patients, and insufficient screening for hepatocellular carcinoma, oesophageal varices, sarcopaenia, minimal hepatic encephalopathy, and diabetes mellitus, along with fibrosis progression and cirrhosis decompensation, can add further complexities. Additionally, devaluing the impact of obesity in triggering liver cirrhosis can be disadvantageous. Prolonged and inappropriate use of proton pump inhibitors also poses a significant challenge with a wide range of complications. These often-unheeded aspects in the care of liver cirrhosis patients represents the unseen culprits of progression from bad to worse and warrant serious consideration.

Implementation and validation of a Bayesian method for accurately forecasting duration of optimal pharmacodynamic target attainment with dalbavancin during long-term use for subacute and chronic staphylococcal infections

Dalbavancin is increasingly being used for long-term treatment of subacute and chronic staphylococcal infections. In this study, a new Bayesian model was implemented and validated using MwPharm software for accurately forecasting the duration of pharmacodynamic target attainment above the efficacy thresholds of 4.02 mg/L or 8.04 mg/L against staphylococci. Forecasting accuracy improved substantially with the a posteriori approach compared with the a priori approach, particularly when two measured concentrations were used. This strategy may help clinicians to estimate the duration of optimal exposure with dalbavancin in the context of long-term treatment.