Population Pharmacokinetic Study of Ceftriaxone in Elderly Patients, Using Cystatin C-Based Estimates of Renal Function To Account for Frailty

Acute upper and lower gastrointestinal bleeding management in older people taking or not taking anticoagulants: a literature review

Acute upper and lower gastrointestinal (GI) bleeding may be a potentially life-threatening event that requires prompt recognition and an early effective management, being responsible for a considerable number of hospital admissions. Methods. We perform a clinical review to summarize the recent international guidelines, helping the physician in clinical practice. Older people are a vulnerable subgroup of patients more prone to developing GI bleeding because of several comorbidities and polypharmacy, especially related to an increased use of antiplatelet and anticoagulant drugs. In addition, older patients may have higher peri-procedural risk that should be evaluated. The recent introduction of reversal strategies may help the management of GI bleeding in this subgroup of patients. In this review, we aimed to (1) summarize the epidemiology and risk factors for upper and lower GI bleeding, (2) describe treatment options with a focus on pharmacodynamics and pharmacokinetics of different proton pump inhibitors, and (3) provide an overview of the clinical management with flowcharts for risk stratification and treatment. In conclusion, GI is common in older patients and an early effective management may be helpful in the reduction of several complications.

A Systematic Literature Review on the Use of Dried Biofluid Microsampling in Patients With Kidney Disease

BACKGROUND

Kidney disease is fairly unique due to the lack of symptoms associated with disease activity, and it is therefore dependent on biological monitoring. Dried biofluids, particularly dried capillary blood spots, are an accessible, easy-to-use technology that have seen increased utility in basic science research over the past decade. However, their use is yet to reach the kidney patient population clinically or in large-scale discovery science initiatives. The aim of this study was to systematically evaluate the existing literature surrounding the use of dried biofluids in kidney research.

METHODS

A systematic literature review was conducted using three search engines and a predefined search term strategy. Results were summarised according to the collection method, type of biofluid, application to kidney disease, cost, sample stability and patient acceptability.

RESULTS

In total, 404 studies were identified and 67 were eligible. In total, 34,739 patients were recruited to these studies with a skew towards male participants (> 73%). The majority of samples were blood, which was used either for monitoring anti-rejection immunosuppressive drug concentrations or for kidney function. Dried biofluids offered significant cost savings to the patient and healthcare service. The majority of patients preferred home microsampling when compared to conventional monitoring.

CONCLUSION

There is an unmet need in bringing dried microsampling technology to advance kidney disease despite its advantages. This technology provides an opportunity to upscale patient recruitment and longitudinal sampling, enhance vein preservation and overcome participation bias in research.

Population pharmacokinetics of antibacterial agents in the older population: a literature review

INTRODUCTION

Older individuals face an elevated risk of developing bacterial infections. The optimal use of antibacterial agents in this population is challenging because of age-related physiological alterations, changes in pharmacokinetics (PK) and pharmacodynamics (PD), and the presence of multiple underlying diseases. Therefore, population pharmacokinetics (PPK) studies are of great importance for optimizing individual treatments and prompt identification of potential risk factors.

AREA COVERED

Our search involved keywords such as 'elderly,' 'old people,' and 'geriatric,' combined with 'population pharmacokinetics' and 'antibacterial agents.' This comprehensive search yielded 11 categories encompassing 28 antibacterial drugs, including vancomycin, ceftriaxone, meropenem, and linezolid. Out of 127 studies identified, 26 (20.5%) were associated with vancomycin, 14 (11%) with meropenem, and 14 (11%) with piperacillin. Other antibacterial agents were administered less frequently.

EXPERT OPINION

PPK studies are invaluable for elucidating the characteristics and relevant factors affecting the PK of antibacterial agents in the older population. Further research is warranted to develop and validate PPK models for antibacterial agents in this vulnerable population.

Ceftriaxone-Related Encephalopathy in a Patient With End-Stage Renal Disease and High Ceftriaxone Concentrations in Cerebrospinal Fluid and Plasma: A Case Report

Ceftriaxone (CTRX) does not require dose adjustment based on the renal function status and is used to treat infections. Recently, several studies reported the incidence of antibiotic-associated encephalopathy due to CTRX in patients with end-stage renal disease (ESRD). We experienced a case of CTRX-related encephalopathy in a patient on hemodialysis. When CTRX-related encephalopathy was discovered, the CTRX concentrations were measured in the blood and cerebrospinal fluid (CSF). The highest blood and CSF CTRX concentrations in this patient were 967 and 100.7 μg/mL, respectively, which were approximately 10 times higher than the CSF concentrations in a previously evaluated patient with CTRX encephalopathy. The concentration of CTRX may be increased in patients with ESRD. Hence, encephalopathy must be suspected in this patient group when CTRX is used.

Pharmacokinetics of Antibacterial Agents in the Elderly: The Body of Evidence

Infections are important factors contributing to the morbidity and mortality among elderly patients. High rates of consumption of antimicrobial agents by the elderly may result in increased risk of toxic reactions, deteriorating functions of various organs and systems and leading to the prolongation of hospital stay, admission to the intensive care unit, disability, and lethal outcome. Both safety and efficacy of antibiotics are determined by the values of their plasma concentrations, widely affected by physiologic and pathologic age-related changes specific for the elderly population. Drug absorption, distribution, metabolism, and excretion are altered in different extents depending on functional and morphological changes in the cardiovascular system, gastrointestinal tract, liver, and kidneys. Water and fat content, skeletal muscle mass, nutritional status, use of concomitant drugs are other determinants of pharmacokinetics changes observed in the elderly. The choice of a proper dosing regimen is essential to provide effective and safe antibiotic therapy in terms of attainment of certain pharmacodynamic targets. The objective of this review is to perform a structure of evidence on the age-related changes contributing to the alteration of pharmacokinetic parameters in the elderly.

Pharmacokinetics and Target Attainment of ß-lactam Antibiotics in Older People: A Systematic Review of Current Literature

BACKGROUND AND OBJECTIVE

(Patho)physiological changes in older people may influence the pharmacokinetics (PK), and consequently the target attainment, of ß-lactam antibiotics using standard dosing regimens. This systematic review compiles the current knowledge on the PK and target attainment of ß-lactam antibiotics in older people, with the aim to identify priorities for dose optimization in this patient population.

METHODS

A systematic literature search of the PubMed and EMBASE databases was conducted. Relevant articles published prior to 1 December 2021 were identified as eligible when they included data on the PK of ß-lactam antibiotics in adults ≥ 65 years of age. Extracted information included reported PK parameters (volume of distribution, clearance [CL], elimination rate constant, intercompartmental CL, elimination half-life, area under the concentration-time curve, maximum and trough concentration), covariates on PK parameters, target attainment rate, and dosing recommendations.

RESULTS

Ninety-one relevant articles were included in this review. Four main ß-lactam subclasses were represented: 59.3% on cephalosporins + cephamycins, 25.3% on penicillins, 15.4% on carbapenems, and 3.3% on monobactams; 65.9% of articles involved intravenous administration, 16.5% mixed administration routes, 12.1% oral administration, and 5.5% intramuscular administration. The majority of studies had a small sample size, often did not include detailed information on the study population and methods, and were fairly old. CL was, on average, decreased, while elimination half-life was prolonged in aged subjects compared with young subjects. Volume of distribution was generally similar between age groups. Most studies identified renal function as the most important contributor to altered drug CL. In only 30.8% of the articles, target attainment was studied, and in 35.7% of these articles, target attainment was found to be suboptimal. Dosing recommendations were incorporated in 87.9% of articles.

CONCLUSION

Studies frequently fail to provide an evidence-based dosing recommendation for this diverse patient population. Model-based PK studies that address both physiological and disease-related changes are urgently needed. This review identified gaps of knowledge to set priorities for further research.

New Horizons in the impact of frailty on pharmacokinetics: latest developments

Frail older people have a high prevalence of drug use and are susceptible to adverse drug reactions. The physiological changes of frailty are likely to affect pharmacokinetics and pharmacodynamics. We reviewed the methods and findings of published studies of pharmacokinetics in frailty. Nine studies describing pharmacokinetics and an additional three of pharmacokinetic pathways in frail older people were identified. Most pharmacokinetic studies investigated a single administration of a medication, dose or formulation, in small populations, often with limited representation of males or females, and applied variable definitions of frailty. Pharmacokinetic sampling designs generally utilised saturated sampling followed by analysis based on the trapezoidal rule for area under the curve, with more recent studies using sparser sampling and more sophisticated modelling to obtain individual and population values of all pharmacokinetic parameters. Overall, the pharmacokinetic studies reported only small changes in some parameters for some drugs with frailty, with the most consistent change reduced hepatic clearance in frail older people. Recommendations for future studies of pharmacokinetics in frailty include (i) standard objective definitions of frailty; (ii) larger studies including people with mild, moderate and severe frailty; (iii) population pharmacokinetic modelling to allow sparser sampling and consideration of multiple influences on pharmacokinetics; (iv) physiologically based modelling as the physiology of frailty emerges and (v) longitudinal pharmacokinetic studies of chronic drug therapy from middle to old age and from robust to pre-frail to frail, including pre-clinical studies. These data, accompanied by pharmacodynamics data in frailty, will inform safe, effective prescribing for frail older people.

Population Pharmacokinetic Analysis and Dosing Optimization Based on Unbound Daptomycin Concentration and Cystatin C in Nonobese Elderly Patients with Hypoalbuminemia and Chronic Kidney Disease

PURPOSE

This study evaluated the population pharmacokinetics of daptomycin in nonobese elderly patients with hypoalbuminemia and chronic kidney disease (CKD) using the glomerular filtration rate estimated from cystatin C (eGFRcys) and estimated its optimal dose.

METHODS

We performed population pharmacokinetic analysis of the unbound concentrations of daptomycin. The probability of target attainment of 90% for achieving an area under the concentration-time curve of unbound daptomycin at steady state/ minimum inhibitory concentration ratio of ≥66.6 was stochastically simulated.

RESULTS

In the population pharmacokinetic analysis of 25 patients aged ≥65 years, the two-compartment model using eGFRcys and age as covariates of clearance in central compartment of unbound daptomycin were optimal. The unbound fraction rate (fu) was 0.05-0.14. According to the Monte Carlo simulation, the optimal doses for patients with eGFRcys of 20-60 mL/min and aged 65-95 years were calculated as 200-500 mg q24h.

CONCLUSION

These results suggest that establishing the dose using total concentrations may result in under- or overestimation caused by alterations in fu. The optimal dose for nonobese elderly patients with hypoalbuminemia and CKD depends on eGFRcys and age, and a standard dose may be insufficient for some patients.

Antimicrobial Dosing in Specific Populations and Novel Clinical Methodologies: Kidney Function

Kidney function is a common parameter used to define antimicrobial drug dosage and frequency of administration. Several methods exist to measure kidney function but for pragmatic reasons rely on estimated kidney function equations based on the endogenous biomarker serum creatinine and common clinical variables. Current regulatory guidance on the design of studies in patients with abnormal kidney function in the United States also recommend consideration of estimated kidney function for this reason. Over the past few decades, alternate endogenous biomarkers, administration of exogenous biomarkers for noninvasive measurement, use of probe substrates to characterize individual kidney drug clearance pathways, modifications to conventional equations to account for time-varying clearance, and improved clinical trial modeling and simulation to factor in these uncertainties have occurred. Furthermore, major changes to kidney replacement therapy delivery in the outpatient, inpatient, and at-home setting are occurring. Antimicrobial drug dose adjustment in this diverse population is complex and in a state of flux due to technical innovations. Over-reliance on kidney function estimates to guide drug dosing in patients with infectious diseases can bias underdosing especially among the acutely ill. A holistic approach to drug dose adjustment in patients with abnormal kidney function is necessary to optimize clinical outcomes.