Age-related changes in protein binding of drugs: implications for therapy

Utility of life stage-specific chemical risk assessments based on New Approach Methodologies (NAMs)

The safety assessments for chemicals targeted for use or expected to be exposed to specific life stages, including infancy, childhood, pregnancy and lactation, and geriatrics, need to account for extrapolation of data from healthy adults to these populations to assess their human health risk. However, often adequate and relevant toxicity or pharmacokinetic (PK) data of chemicals in specific life stages are not available. For such chemicals, New Approach Methodologies (NAMs), such as physiologically based pharmacokinetic (PBPK) modeling, biologically based dose response (BBDR) modeling, in vitro to in vivo extrapolation (IVIVE), etc. can be used to understand the variability of exposure and effects of chemicals in specific life stages and assess their associated risk. A life stage specific PBPK model incorporates the physiological and biochemical changes associated with each life stage and simulates their impact on the absorption, distribution, metabolism, and elimination (ADME) of these chemicals. In our review, we summarize the parameterization of life stage models based on New Approach Methodologies (NAMs) and discuss case studies that highlight the utility of a life stage based PBPK modeling for risk assessment. In addition, we discuss the utility of artificial intelligence (AI)/machine learning (ML) and other computational models, such as those based on in vitro data, as tools for estimation of relevant physiological or physicochemical parameters and selection of model. We also discuss existing gaps in the available toxicological datasets and current challenges that need to be overcome to expand the utility of NAMs for life stage-specific chemical risk assessment.

The regional pattern of age-related synaptic loss in the human brain differs from gray matter volume loss: in vivo PET measurement with [11C]UCB-J

PURPOSE

Aging is a major societal concern due to age-related functional losses. Synapses are crucial components of neural circuits, and synaptic density could be a sensitive biomarker to evaluate brain function. [11C]UCB-J is a positron emission tomography (PET) ligand targeting synaptic vesicle glycoprotein 2A (SV2A), which can be used to evaluate brain synaptic density in vivo.

METHODS

We evaluated age-related changes in gray matter synaptic density, volume, and blood flow using [11C]UCB-J PET and magnetic resonance imaging (MRI) in a wide age range of 80 cognitive normal subjects (21-83 years old). Partial volume correction was applied to the PET data.

RESULTS

Significant age-related decreases were found in 13, two, and nine brain regions for volume, synaptic density, and blood flow, respectively. The prefrontal cortex showed the largest volume decline (4.9% reduction per decade: RPD), while the synaptic density loss was largest in the caudate (3.6% RPD) and medial occipital cortex (3.4% RPD). The reductions in caudate are consistent with previous SV2A PET studies and likely reflect that caudate is the site of nerve terminals for multiple major tracts that undergo substantial age-related neurodegeneration. There was a non-significant negative relationship between volume and synaptic density reductions in 16 gray matter regions.

CONCLUSION

MRI and [11]C-UCB-J PET showed age-related decreases of gray matter volume, synaptic density, and blood flow; however, the regional patterns of the reductions in volume and SV2A binding were different. Those patterns suggest that MR-based measures of GM volume may not be directly representative of synaptic density.

Treatment of Bipolar Disorders in Older Adults: A Review

Background

Old age bipolar disorder has been an orphan of psychiatric research for a long time despite the fact that bipolar disorder (BD)-I and II together may affect 0.5-1.0% of the elderly. It is also unclear whether aetiology, course of illness and treatment should differ in patients with a first manifestation in older age and patients suffering from a recurrence of a BD known for decades. This narrative review will summarize the current state of knowledge about the epidemiology, clinical features, and treatment of BD in the elderly.

Methods

We conducted a Medline literature search from 1970 to 2021 using MeSH terms "Bipolar Disorder" × "Aged" or "Geriatric" or "Elderly". Search results were complemented by additional literature retrieved from examining cross references and by hand search in text books.

Summary of findings

Varying cut-off ages have been applied to differentiate old age from adult age BD. Within old age BD, there is a reasonable agreement of distinct entities, early and late-onset BD. They differ to some extent in clinical symptoms, course of illness, and some co-morbidities. Point prevalence of BD in older adults appears slightly lower than in working-age adults, with polarity of episodes shifting towards depression. Psychopharmacological treatment needs to take into account the special aspects of somatic gerontology and the age-related change of pharmacokinetic and pharmacodynamic characteristics. The evidence for commonly used treatments such as lithium, moodstabilizing antiepileptics, antipsychotics, and antidepressants remains sparse. Preliminary results support a role of ECT as well as psychotherapy and psychosocial interventions in old age BD.

Conclusions

There is an obvious need of further research for all treatment modalities of BD in old age. The focus should be pharmacological and psychosocial approaches, as well as their combination, and the role of physical treatment modalities such as ECT.Appeared originally in Ann Gen Psychiatry 2021; 20:1.

Pro-arrhythmic effect of escitalopram and citalopram at serum concentrations commonly observed in older patients - a study based on a cohort of 19,742 patients

BACKGROUND

For a decade, patients have been advised against using high citalopram- and escitalopram-doses due to risk for ventricular arrhythmia and cardiac arrest. Still, these drugs are widely used to treat depression and anxiety especially in older patients. It is unclear why they are cardiotoxic and at what serum concentrations patients are at risk for arrhythmias. Thus, how many patients that are at risk for iatrogenic cardiac arrest is unknown.

METHODS

We studied the arrhythmogenic effects of citalopram, escitalopram and their metabolites on human cardiomyocytes. Concentrations showing pro-arrhythmic activity were compared with observed drug and metabolite serum concentrations in a cohort of 19,742 patients (age 12-105 years) using escitalopram or citalopram in Norway (2010-2019). As arrhythmia-risk is related to maximum serum concentration, this was simulated for different age-groups from the escitalopram patient material.

FINDINGS

Therapeutic concentrations of both citalopram and escitalopram but not their metabolites showed pro-arrhythmic changes in the human cardiac action potential. Due to age-dependent reduction of drug clearance, the proportion of patients above threshold for arrhythmia-risk increased with age. 20% of patients >65 years were predicted to reach potentially pro-arrhythmic concentrations, following intake of 10 mg escitalopram.

INTERPRETATION

All patients that are using escitalopram or citalopram and have genetic disposition for acquired long-QT syndrome, are >65 years, are using additional pro-arrhythmic drugs or have predisposition for arrhythmias, should be monitored with therapeutic drug monitoring (TDM) to avoid exposure to potentially cardiotoxic concentrations. Serum concentrations should be kept below 100 nM, to reduce arrhythmia-risk.

FUNDING

This study was funded by The Research Council of Norway (project number: 324062).

A Neuroscience Primer for Integrating Geroscience With the Neurobiology of Aging

Neuroscience has a rich history of studies focusing on neurobiology of aging. However, much of the aging studies in neuroscience occur outside of the gerosciences. The goal of this primer is 2-fold: first, to briefly highlight some of the history of aging neurobiology and second, to introduce to geroscientists the broad spectrum of methodological approaches neuroscientists use to study the neurobiology of aging. This primer is accompanied by a corresponding geroscience primer, as well as a perspective on the current challenges and triumphs of the current divide across these 2 fields. This series of manuscripts is intended to foster enhanced collaborations between neuroscientists and geroscientists with the intent of strengthening the field of cognitive aging through inclusion of parameters from both areas of expertise.

The impact of advanced age on anticoagulant therapy for acute venous thromboembolism

INTRODUCTION

Management of venous thromboembolic events (VTE) has been completely changed after the introduction of direct oral anticoagulants (DOAC). VTE is common in the geriatric population, but the management of DOACs remains complex because of the lack of specific data in this polymedicated fragile population.An exhaustive search of anticoagulants in the indication of VTE was performed on PubMed, including data from clinical trials, observational studies, real-world data, drug-drug interaction studies, as well as various guidelines from scientific societies.

AREAS COVERED

The present review aims to summarize our current knowledge on the era of DOACs in the management of VTE in the elderly. This involves learning the pharmacokinetics/pharmacodynamics of drugs specific to geriatrics, the problem of drug-drug interactions, and the main randomized clinical trials validating the use of DOACs.

EXPERT OPINION

DOACs have become an essential part of the management of VTE in the elderly, both for their efficacy and safety. However, we are faced with a list of unmet needs, such as the relevance of DOACs in the very elderly, cancer patients, and those with renal impairment. Clinicians and pharmacists must remain cautious about comedications, as well as about the patient's comorbidities.

Treatment of bipolar disorders in older adults: a review

BACKGROUND

Old age bipolar disorder has been an orphan of psychiatric research for a long time despite the fact that bipolar disorder (BD)-I and II together may affect 0.5-1.0% of the elderly. It is also unclear whether aetiology, course of illness and treatment should differ in patients with a first manifestation in older age and patients suffering from a recurrence of a BD known for decades. This narrative review will summarize the current state of knowledge about the epidemiology, clinical features, and treatment of BD in the elderly.

METHODS

We conducted a Medline literature search from 1970 to 2021 using MeSH terms "Bipolar Disorder" × "Aged" or "Geriatric" or "Elderly". Search results were complemented by additional literature retrieved from examining cross references and by hand search in text books. Varying cut-off ages have been applied to differentiate old age from adult age BD. Within old age BD, there is a reasonable agreement of distinct entities, early and late-onset BD. They differ to some extent in clinical symptoms, course of illness, and some co-morbidities. Point prevalence of BD in older adults appears slightly lower than in working-age adults, with polarity of episodes shifting towards depression. Psychopharmacological treatment needs to take into account the special aspects of somatic gerontology and the age-related change of pharmacokinetic and pharmacodynamic characteristics. The evidence for commonly used treatments such as lithium, mood-stabilizing antiepileptics, antipsychotics, and antidepressants remains sparse. Preliminary results support a role of ECT as well as psychotherapy and psychosocial interventions in old age BD.

CONCLUSIONS

There is an obvious need of further research for all treatment modalities of BD in old age. The focus should be pharmacological and psychosocial approaches, as well as their combination, and the role of physical treatment modalities such as ECT.

Safety, Pharmacokinetics, and Pharmacodynamics of a Single Bolus of the γ-aminobutyric Acid (GABA) Receptor Potentiator HSK3486 in Healthy Chinese Elderly and Non-elderly

Background: The present clinical trial investigated the potential influences of dosage and age on the pharmacokinetic properties and safety profile of HSK3486, and whether any adjustment in dosing regimen is necessary in elderly patients.

Methods: Twenty-four elderly participants (65–73 years) were apportioned to three equal cohorts to receive a single IV bolus of 0.2, 0.3, and 0.4 mg/kg HSK3486, respectively. An additional control group comprised eight non-elderly participants (21–44 years), who each received a single IV bolus dose of 0.4 mg/kg. Safety was assessed throughout the study, and the clinical effects were assessed based on modified observer’s assessment of alertness/sedation and bispectral index (BIS) monitor. Pharmacokinetic parameters were calculated.

Results: The rates of drug-related adverse reactions among the elderly groups were a little higher than that of the non-elderly, and were slightly higher in the elderly receiving 0.4 mg/kg compared with the elderly given lower doses. The pharmacokinetic characteristics of 0.4 mg/kg HSK3486 in the elderly and non-elderly were comparable. The time to recovery was similar in elderly 0.3 mg/kg, elderly 0.4 mg/kg and non-elderly 0.4 mg/kg groups. In the elderly 0.2 mg/kg group, the time to loss of consciousness was a little longer, and the time to recovery was shorter, relative to the other three groups.

Conclusions: Administration of 0.3 mg/kg to the elderly and 0.4 mg/kg to the non-elderly were similarly efficacious. A dose of HSK3486 of 0.3 mg/kg may be chosen for clinical use in elderly patients.

Optimizing a High-Throughput Solid-Phase Microextraction System to Determine the Plasma Protein Binding of Drugs in Human Plasma

Plasma protein binding refers to the binding of a drug to plasma proteins after entering the body. The measurement of plasma protein binding is essential during drug development and in clinical practice, as it provides a more detailed understanding of the available free concentration of a drug in the blood, which is in turn critical for pharmacokinetics and pharmacodynamics studies. In addition, the accurate determination of the free concentration of a drug in the blood is also highly important for therapeutic drug monitoring and in personalized medicine. The present study uses C₁₈-coated solid-phase microextraction 96-pin devices to determine the free concentrations of a set of drugs in plasma, as well as the plasma protein binding of drugs with a wide range of physicochemical properties. It should be noted that the extracted amounts used to calculate the binding constants and plasma protein bindings should be measured at respective equilibrium for plasma and phosphate buffer. Therefore, special attention is placed on properly determining the equilibration times required to correctly estimate the free concentrations of drugs in the investigated systems. The plasma protein binding values obtained with the 96-pin devices are consistent with those reported in the literature. The 96-pin device used in this research can be easily coupled with a Concept96 or other automated robotic systems to create an automated plasma protein binding determination protocol that is both more time and labor efficient compared to conventional equilibrium dialysis and ultrafiltration methods.

Antithrombotic therapy in the elderly and senile age: the consensus opinion of experts of the Russian Association of Gerontologists and Geriatricians and the National Society of Preventive Cardiology

В данном документе обсуждаются особенности АТТ у лиц пожилого и старческого возраста в различных клинических ситуациях.

Serious Neurological Adverse Events of Ceftriaxone

We described ceftriaxone-induced CNS adverse events through the largest case series of Adverse Drug Reactions (ADRs) reports, from 1995 to 2017, using the French Pharmacovigilance Database. In total, 152 cases of serious CNS ADRs were analyzed; 112 patients were hospitalized or had a prolonged hospitalization (73.7%), 12 dead (7.9%) and 16 exhibited life-threatening ADRs (10.5%). The median age was 74.5 years, mainly women (55.3%), with a median creatinine clearance of 35 mL/min. Patients mainly exhibited convulsions, status epilepticus, myoclonia (n = 75, 49.3%), encephalopathy (n = 45, 29.6%), confused state (n = 34, 22.4%) and hallucinations (n = 16, 10.5%). The median time of onset was 4 days, and the median duration was 4.5 days. The mean daily dose was 1.7 g mainly through an intravenous route (n = 106, 69.7%), and three patients received doses above maximal dose of Summary of Product Characteristics. Ceftriaxone plasma concentrations were recorded for 19 patients (12.5%), and 8 were above the toxicity threshold. Electroencephalograms (EEG) performed for 32.9% of the patients (n = 50) were abnormal for 74% (n = 37). We described the world's biggest case series of ceftriaxone-induced serious CNS ADRs. Explorations (plasma concentrations, EEG) are contributive to confirm the ceftriaxone toxicity-induced. Clinicians may be cautious with the use of ceftriaxone, especially in the older age or renal impairment population.

Pharmacokinetics and Safety of Chiglitazar, a Peroxisome Proliferator-Activated Receptor Pan-Agonist, in Patients < 65 and ≥ 65 Years With Type 2 Diabetes

The effect of age on the pharmacokinetics and safety of chiglitazar was evaluated in patients < 65 and ≥ 65 years with type 2 diabetes mellitus (T2DM). A total of 20 T2DM patients (<65 vs ≥65 years 1:1) completed the study. Patients received multiple doses of 48 mg chiglitazar once daily for 7 days consecutively. After the first dosing, chiglitazar maximum plasma concentration (C_max ) and area under the plasma concentration-time curve (AUC) in patients ≥ 65 years were similar to those observed in patients < 65 years, with the geometric mean ratio (GMR) for C_max and AUC being 97.22% and 96.83%, respectively. No significant difference was observed in C_max (GMR, 97.23%) in the steady state. Compared with the patients < 65 years, a slight increase (8%-13%) of AUC was observed in the patients ≥ 65 years after multiple doses. Chiglitazar was generally well tolerated following multiple doses in both age groups. In conclusion, there were no significant clinical influences on the pharmacokinetic properties and safety profiles of chiglitazar between patients with T2DM < 65 and ≥ 65 years, indicating that in the future it is not required to adjust the dosing regimen by age for T2DM patients ≥ 65 years.

Alterations in drug disposition in older adults: a focus on geriatric syndromes

INTRODUCTION

Age-associated physiological changes can alter the disposition of drugs, however, pathophysiological changes associated with geriatric syndromes in older adults may lead to even greater heterogeneity in pharmacokinetics. Geriatric syndromes are common health problems in older adults which have multifactorial causes and do not fit into distinct organ-based disease categories. With older adults being the greatest users of medications, understanding both age- and geriatric syndrome-related changes is important clinically to ensure safe and effective medication use.

AREAS COVERED

This review provides an overview of current evidence regarding pharmacokinetic alterations that occur with aging and in common geriatric syndromes, including frailty, sarcopenia, dementia, polypharmacy and enteral feeding. The evidence is presented according to the four primary pharmacokinetic processes (Absorption, Distribution, Metabolism and Excretion).

EXPERT OPINION

There is some evidence to inform our understanding of the impact of chronological aging and various geriatric syndromes on drug disposition. However, many areas require more research, including drug induced inhibition and induction of cytochrome P450 enzymes and the clinical utility of emerging methods for estimating renal function. There is a need to develop tools to predict alterations in drug disposition in subgroups of older adults, particularly where the currently available clinical information is sparse.

Anesthetic management of a "Supercentenarian" (Oldest living person on Earth) posted for an emergency surgery

With the rise in living standards and evolution of science, there is a rise in life expectancy world over. This demographic transition has led to a rise in older persons, increasing the dependency ratios and “demographic burden.” Management of such old patients requires special considerations and understanding as aging is a physiological phenomenon in which the functional capacity of organs decreases due to degenerative changes in the structure. An important aspect to remember in Geriatric Anesthesia is that in spite of adequate compensatory mechanisms for age-related changes, there is a limitation of physiological reserve, especially in stressful circumstances like perioperative period. Geriatric patients are more sensitive to all medications and anesthetic agents. Lesser amount of drug is required to achieve the desired clinical effect, but have a prolonged effect. This elderly but well-preserved patient, possibly a case of small gut obstruction was posted for emergency laparoscopy and proceed. Seeing his age and easy friability, a well-planned preoperative assessment and optimization was done prior to wheeling him into operation theater. Administration of short-acting anesthetic drugs in titrated quantities and awareness about postoperative cognitive dysfunction (POCD) helped us to get better and faster recovery in the patient.

Effectiveness and Safety of Oral Anticoagulants in Older Patients With Atrial Fibrillation: A Systematic Review and Meta-Analysis

Background and Objective

Atrial fibrillation (AF), the most common cardiac arrhythmia, typically increases with age. Oral anticoagulants (OACs) are the cornerstone of treatment to reduce the associated risk for systemic thromboembolism. Four large randomized controlled trials (RCTs) have shown that non-vitamin K antagonist oral anticoagulants (NOACs) are non-inferior to vitamin K antagonists (VKAs) in preventing stroke and systemic embolism, as well as regarding their risk for major bleeding. However, as vulnerable geriatric patients with AF were largely underrepresented in these trials, physicians are faced with the challenge of choosing the right anticoagulant for geriatric patients in real-life clinical practice. In this vulnerable patient group, NOACs tend to be underused or underdosed due to concerns of excessive fall-related intracranial bleeding, cognitive impairment, multiple drug-drug interactions, low body weight or impaired renal function. As life expectancy continues to rise worldwide, the number of geriatric patients substantially increases. Therefore, there is an urgent need for a critical appraisal of the added value of NOACs in geriatric patients with AF at high thromboembolic and bleeding risk.

Methods and Results

This systematic review provides an overview of the literature on the impact of increased age (≥75 years), multimorbidity, polypharmacy, increased falling risk, frailty and dementia on the effectiveness and safety of NOACs as compared to VKAs, after searching the Medline database. Moreover, a meta-analysis on the impact of increased age ≥75 years old was performed after pooling results from 6 post hoc analyses of RCTs and 6 longitudinal observational cohort studies, highlighting the superior effectiveness (hazard ratio (HR) 0.83, 95% confidence interval (CI) [0.74–0.94] for stroke/SE; HR 0.77, 95%CI [0.65–0.92] for mortality) and non-inferior safety (HR 0.93, 95%CI [0.86–1.01] for major bleeding; HR 0.58, 95%CI [0.50–0.67] for intracranial bleeding; HR 1.17, 95%CI [0.99–1.38] for gastrointestinal bleeding) of NOACs versus VKAs in older AF patients.

Conclusion

Across geriatric subgroups, apixaban was consistently associated with the most favourable benefit-risk profile and should therefore be preferred in geriatric patients with AF. However, research gaps on the impact of increased falling risk, frailty and baseline dementia were identified, requiring careful consideration while awaiting more results.

Structural Basis of Drug Recognition by Human Serum Albumin

Background:

Human serum albumin (HSA), the most abundant protein in plasma, is a monomeric multi-domain macromolecule with at least nine binding sites for endogenous and exogenous ligands. HSA displays an extraordinary ligand binding capacity as a depot and carrier for many compounds including most acidic drugs. Consequently, HSA has the potential to influence the pharmacokinetics and pharmacodynamics of drugs.

Objective:

In this review, the structural determinants of drug binding to the multiple sites of HSA are analyzed and discussed in detail. Moreover, insight into the allosteric and competitive mechanisms underpinning drug recognition, delivery, and efficacy are analyzed and discussed.

Conclusion:

As several factors can modulate drug binding to HSA (e.g., concurrent administration of drugs competing for the same binding site, ligand binding to allosteric-coupled clefts, genetic inherited diseases, and post-translational modifications), ligand binding to HSA is relevant not only under physiological conditions, but also in the pharmacological therapy management.

Ruxolitinib binding to human serum albumin: bioinformatics, biochemical and functional characterization in JAK2V617F+ cell models

Ruxolitinib is a type I JAK inhibitor approved by FDA for targeted therapy of Philadelphia-negative myeloproliferative neoplasms (MPNs), all characterized by mutations activating the JAK2/STAT signaling pathway. Treatment with ruxolitinib improves constitutional symptoms and splenomegaly. However, patients can become resistant to treatment and chronic therapy has only a mild effect on molecular/pathologic remissions. Drugs interaction with plasma proteins, i.e. human serum albumin (HSA), is an important factor affecting the intensity and duration of their pharmacological actions. Here, the ruxolitinib recognition by the fatty acid binding sites (FAs) 1, 6, 7, and 9 of HSA has been investigated from the bioinformatics, biochemical and/or biological viewpoints. Docking simulations indicate that ruxolitinib binds to multiple sites of HSA. Ruxolitinib binds to the FA1 and FA7 sites of HSA with high affinity (K_r = 3.1 μM and 4.6 μM, respectively, at pH 7.3 and 37.0 °C). Moreover, HSA selectively blocks, in a dose dependent manner, the cytotoxic activity of ruxolitinib in JAK2V617F⁺ cellular models for MPN, in vitro. Furthermore this event is accompanied by changes in the cell cycle, p27^Kip1 and cyclin D3 levels, and JAK/STAT signaling. Given the high plasma concentration of HSA, ruxolitinib trapping may be relevant in vivo.

Geriatric Pharmacology: An Update

An aging worldwide population demands that anesthesiologists consider geriatrics a unique subset of patients requiring customization of practice. This article reviews the current literature investigating physiologic changes of the elderly that affect pharmacokinetics and pharmacodynamics. Changes in drug absorption, distribution, metabolism, and excretion are discussed as well as the ultimate effects of medications. Implications for practice regarding specific anesthetic and analgesic drugs are addressed. Despite the immense body of research that contributes to understanding of geriatric pharmacology, elderly patients often are excluded from rigorous research trials, and further scientific investigation to inform best practices for this group of patients is needed.

Pharmacokinetics of enrofloxacin and danofloxacin in premature calves

The aim of this study was to determine the pharmacokinetics/pharmacodynamics of enrofloxacin (ENR) and danofloxacin (DNX) following intravenous (IV) and intramuscular (IM) administrations in premature calves. The study was performed on twenty-four calves that were determined to be premature by anamnesis and general clinical examination. Premature calves were randomly divided into four groups (six premature calves/group) according to a parallel pharmacokinetic (PK) design as follows: ENR-IV (10 mg/kg, IV), ENR-IM (10 mg/kg, IM), DNX-IV (8 mg/kg, IV), and DNX-IM (8 mg/kg, IM). Plasma samples were collected for the determination of tested drugs by high-pressure liquid chromatography with UV detector and analyzed by noncompartmental methods. Mean PK parameters of ENR and DNX following IV administration were as follows: elimination half-life (t_1/2λz ) 11.16 and 17.47 hr, area under the plasma concentration-time curve (AUC_0-48 ) 139.75 and 38.90 hr*µg/ml, and volume of distribution at steady-state 1.06 and 4.45 L/kg, respectively. Total body clearance of ENR and DNX was 0.07 and 0.18 L hr^-1  kg^-1 , respectively. The PK parameters of ENR and DNX following IM injection were t_1/2λz 21.10 and 28.41 hr, AUC_0-48 164.34 and 48.32 hr*µg/ml, respectively. The bioavailability (F) of ENR and DNX was determined to be 118% and 124%, respectively. The mean AUC_0-48CPR /AUC_0-48ENR ratio was 0.20 and 0.16 after IV and IM administration, respectively, in premature calves. The results showed that ENR (10 mg/kg) and DNX (8 mg/kg) following IV and IM administration produced sufficient plasma concentration for AUC_0-24 /minimum inhibitory concentration (MIC) and maximum concentration (C_max )/MIC ratios for susceptible bacteria, with the MIC₉₀ of 0.5 and 0.03 μg/ml, respectively. These findings may be helpful in planning the dosage regimen for ENR and DNX, but there is a need for further study in naturally infected premature calves.

Effect of age on the pharmacokinetics and distribution of tulathromycin in interstitial and pulmonary epithelial lining fluid in healthy calves

OBJECTIVE To compare the plasma pharmacokinetics of tulathromycin between 3-week-old (preweaned) and 6-month-old (weaned) calves and to characterize the distribution of tulathromcyin into pulmonary epithelial lining fluid (PELF) and interstitial fluid (ISF) of preweaned and weaned calves following SC administration of a single dose (2.5 mg/kg). ANIMALS 8 healthy 3-week-old and 8 healthy 6-month-old Holstein steers. PROCEDURES A jugular catheter and SC ultrafiltration probe were aseptically placed in the neck of each calf before tulathromycin administration. Blood, ISF, and bronchoalveolar lavage fluid samples were collected at predetermined times before and after tulathromycin administration for quantification of drug concentration. A urea dilution method was used to estimate tulathromycin concentration in PELF from that in bronchoalveolar lavage fluid. Tulathromycin-plasma protein binding was determined by in vitro methods. Plasma pharmacokinetics were determined by a 2-compartment model. Pharmacokinetic parameters and drug concentrations were compared between preweaned and weaned calves. RESULTS Clearance and volume of distribution per fraction of tulathromycin absorbed were significantly greater for weaned calves than preweaned calves. Tulathromycin-plasma protein binding was significantly greater for weaned calves than preweaned calves. Maximum PELF tulathromycin concentration was significantly greater than the maximum plasma and maximum ISF tulathromycin concentrations in both groups. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that age affected multiple pharmacokinetic parameters of tulathromycin, likely owing to physiologic changes as calves mature from preruminants to ruminants. Knowledge of those changes may be useful in the development of studies to evaluate potential dose adjustments during treatment of calves with respiratory tract disease.

Geriatric pharmacotherapy: Appraising new drugs for neurologic disorders in older patients

New drug development for neurologic disorders has one of the highest attrition rates of all clinical drug developments. This is problematic when, with innovative technology available in so many aspects of life, modern societies expect to have effective treatments for neurodegenerative disorders and mental health conditions that provide something beyond simple symptomatic relief-the expectation is treatment that impacts and mitigates fundamental mechanisms that drive these disorders. The disease burden of neurologic disorders remains extremely high, whereas the proportion of patients receiving effective therapy is relatively low, demonstrating a sizeable unmet medical need. Whether for novel breakthrough therapies or for drugs considered successful, deciding on the basis of clinical trial data whether a particular treatment will be effective for a specific patient is always a leap of faith. However, expertise at reading trial results combined with knowledge of the patient and of his or her disease, together with an understanding of the effect of age on drug pharmacokinetics and pharmacodynamics, the effect of age on the patient's condition, and the effect of age on the patient's life and outlook will ensure the landing is safe. The focus of this article is to provide such knowledge and thereby optimize this expertise.

Challenges and innovations of drug delivery in older age

Both drug delivery performance and various age-related physical, mental and physiological changes can affect drug effectiveness and safety in elderly patients. The many drug delivery systems developed over the years include recent novel transdermal, nasal, pulmonary and orally disintegrating tablets that provide consistent, precise, timely and more targeted drug delivery. Certain drug delivery systems may be associated with suboptimal outcomes in the elderly because of the nature of drug present, a lack of appreciation of the impact of age-related changes in drug absorption, distribution and clearance, the limited availability of pharmacokinetic, safety and clinical data. Polypharmacy, patient morbidity and poor adherence can also contribute to sub-optimal drug delivery systems outcomes in the elderly. The development of drug delivery systems for the elderly is a poorly realised opportunity, with each system having specific advantages and limitations. A key challenge is to provide the innovation that best meets the specific physiological, psychological and multiple drug requirements of individual elderly patients.

Total flucloxacillin plasma concentrations poorly reflect unbound concentrations in hospitalized patients with Staphylococcus aureus bacteraemia

AIMS

Flucloxacillin dosing may be guided by measurement of its total plasma concentrations. Flucloxacillin is highly protein bound with fraction unbound in plasma (f_u ) of around 0.04 in healthy individuals. The utility of measuring unbound flucloxacillin concentrations for patients outside the intensive care unit (ICU) is not established. We aimed to compare flucloxacillin f_u in non-ICU hospitalised patients against healthy volunteers, and to examine the performance of a published model for predicting unbound concentrations, using total flucloxacillin and plasma albumin concentrations.

METHODS

Data from 12 healthy volunteers (248 samples) and 47 hospitalized patients (61 samples) were examined. Plasma flucloxacillin concentrations were measured using a validated liquid chromatography-tandem mass spectrometry method. Flucloxacillin f_u for the two groups was compared using a generalized estimating equation model to account for clustered observations. The performance of the single protein binding site prediction model in hospitalized patients was compared with measured unbound concentrations using Bland-Altman plots.

RESULTS

The median (range) flucloxacillin f_u for healthy (median albumin 45 g l^-1 ) and hospitalized individuals (median albumin 30 g l^-1 ) were 0.04 (0.02-0.07) and 0.10 (0.05-0.37), respectively (P < 0.0001). The prediction model underpredicted unbound flucloxacillin concentrations with a mean bias (95% limits of agreement) of -54% (-137%, +30%).

CONCLUSIONS

The flucloxacillin f_u values observed in our cohort of hospitalized patients had a wide range and were greater than those of healthy individuals. Unbound flucloxacillin plasma concentrations were predicted poorly by the model. Instead, unbound concentrations should be measured to guide dosing.

Therapeutic challenges in the mature patient

With the tremendous increase in the proportion of seniors in the global population, geriatric health care has become of greater interest and concern. Increased emphasis on geriatric medicine, along with the growth in the development of age-related skin disorders, has led to particular attention for geriatric, dermatology and dermatopharmacology. An aging population has brought many therapeutic challenges that we need to recognize and overcome by applying geropharmacologic principles. The purpose of this paper is to inform dermatologists of the age-related changes in the pharmacokinetics of common dermatologic drugs, their various interactions potentially occurring in the elderly, and the principles and evidence-based strategies for detection, management, and prevention to improve medication adherence. By implementing these principles and strategies, we can ensure the best and the safest treatment to promote the desired therapeutic outcome and improved quality of life for this fragile subpopulation.

Factors predictive of the onset and duration of action of local anesthesia in mandibular third-molar surgery: a prospective study

The aim of this study was to assess the influence of patients' and surgical variables on the onset and duration of action of local anesthesia (LA) in mandibular third-molar (M3) surgery. Patients scheduled for mandibular M3 surgery were considered for inclusion in this prospective cohort study. Patients' and surgical variables were recorded. Two per cent (2%) lidocaine with 1:100,000 epinephrine was used to block the nerves for extraction of mandibular M3. Then, the onset of action and duration of LA were monitored. Univariate analysis and multivariate regression analysis were used to analyze the data. The final cohort included 88 subjects (32 men and 56 women; mean age ± SD = 29.3 ± 12.3 yr). With univariate analysis, age, gender, body mass index (BMI), smoking quantity and duration, operation time, and 'volume of local anesthetic needed' significantly influenced the onset of action and duration of LA. Multivariate regression revealed that age and smoking quantity were the only statistically significant predictors of the onset of action of LA, whereas age, smoking quantity, and 'volume of local anesthetic needed' were the only statistically significant predictors of duration of LA. Further studies are recommended to uncover other predictors of the onset of action and duration of LA.

The effects of advanced age and serum α1 -acid glycoprotein on docetaxel unbound exposure and dose-limiting toxicity in cancer patients

AIM

α₁ -Acid glycoprotein (AAG), which is a major binding protein of docetaxel, is considered to be a determinant for docetaxel pharmacokinetics. However, there are no reports about the impact of serum AAG on pharmacokinetics and pharmacodynamics in elderly patients treated with docetaxel. The aim of this prospective study was to elucidate the effects of advanced age and serum AAG on docetaxel unbound exposure and neutropenia, dose-limiting toxicity, in cancer patients.

METHODS

Docetaxel was administered at 60 mg m^-2 to 51 patients with non-small cell lung cancer, 17 of whom were ≥75 years of age. Pharmacokinetics, unbound fraction (fu), neutropenia, serum protein levels of AAG and albumin, as well as baseline absolute neutrophil count (ANC) were assessed during the first course. Population pharmacokinetic and pharmacodynamic analyses were performed to evaluate the influence of clinically relevant factors on docetaxel pharmacokinetics and neutropenia.

RESULTS

Clearance of docetaxel and degree of fu were significantly associated with serum AAG level, but not with age. Area under the concentration-time curve of unbound docetaxel (fu·AUC) was significantly higher in patients aged ≥75 years (0.389 μg·h ml^-1 , 95% CI; 0.329-0.448 μg·h ml^-1 ) compared with patients aged <75 years (0.310 μg·h ml^-1 , 95% CI; 0.268-0.352 μg·h ml^-1 ). Percent decrease in ANC at nadir related to fu·AUC, and was dependent on baseline ANC.

CONCLUSION

Regardless of ageing, serum level of AAG determines docetaxel unbound exposure and related dose-limiting toxicity. Serum AAG level and ANC at baseline appear to be predictive of neutropenia for patients of all ages following the administration of docetaxel.

Effect of lipid emulsion infusion on paliperidone pharmacokinetics in the acute overdose rat model: A potential emergency treatment for paliperidone intoxication

Paliperidone prolongs cardiac repolarization in a concentration-dependent manner. Meanwhile, continuous infusion of intravenous lipid emulsion (ILE) has been established as a detoxification therapy for lipophilic drugs. However, this change in pharmacokinetics of various drugs following ILE administration remains to be clarified. Our objective is to clarify the effect of continuous infusion of ILE on the pharmacokinetics of overdosed paliperidone in rats. Paliperidone (20mg/kg) was administered orally to free-moving male Wistar rats. Continuous infusion (initial loading dose: 4ml/kg for 10min, followed by 4ml/kg/h for 12h) of ILE or acetated Ringer's solution (AR) was initiated 30min after paliperidone administration. Plasma concentration profile of paliperidone was monitored for 12h after administration. The plasma concentration and tissue/plasma concentration ratios of paliperidone were compared between ILE and AR groups. The rat group infused with ILE showed a higher area under the concentration-time curve (mean [S.D.]: 6102 [900.9] vs. 3407 [992.1]nghml^-1, p=0.02) and longer elimination half-time (t_1/2) (4.1 [0.9] vs. 2.2 [0.4]h, p=0.02) compared with the AR group. Tissue/plasma concentration ratios of paliperidone were lower in ILE rats than in AR rats (1.98 [0.70] vs. 3.82 [1.47] in the heart, p=0.04; 0.28 [0.29] vs. 1.27 [0.58] in the brain, p<0.001). In conclusion, continuous infusion of ILE would reduce tissue distribution and prolonged the t_1/2 of paliperidone in rats. These results suggest that continuous infusion of ILE has potential as an emergency treatment for acute paliperidone intoxication.

Perioperative Management of Elderly Patients with Gastrointestinal Malignancies: The Contribution of Anesthesia

INTRODUCTION

Elderly patients suffering from gastrointestinal malignancies are particularly prone to perioperative complications. Elderly patients often present with reduced physiological reserves, and comorbidities can limit treatment options and promote complications. Surgeons and anesthesiologists must be aware of strategies required to deal with this vulnerable subgroup.

METHODS

We provide a brief review of current and emerging perioperative strategies for the treatment of elderly patients with gastrointestinal malignancies and frequent comorbidities.

RESULTS

Especially in combination with advanced age, the effects of malignancies can be devastating, bringing new health challenges, exacerbating preexisting conditions, and exerting severe psychological strain. An interdisciplinary assessment and process planning provide an ideal setting to identify and prevent potential complications, especially in regards to frailty and cardiovascular risk. In addition, important perioperative considerations are presented, such as malnutrition, fasting, intraoperative neuromonitoring, and hemodynamic control, as well as postoperative early mobilization, pain, and delirium management.

CONCLUSION

The decisions and interventions made in the perioperative stage can positively influence many intra- and postoperative factors, significantly improving the chances of successful treatment of elderly cancer patients. Appropriate management can help prevent or mitigate complications, secure a quick recovery, and improve short- and long-term outcomes.

Age and sex in drug development and testing for adults

Individualization of drug therapy requires that the right drug be administered at the correct dose to patients who are likely to achieve the highest benefit and lowest risk. Female sex and age comprise two important risk factors for altered drug exposure and response. This review summarizes the current state of science for considering age and sex-related factors along the drug development pipeline, from cell culture and animal research through all phases of clinical trials in humans. A set of recommendations is provided to improve standards for integrating age and sex into the study design, analysis, and reporting of pre-clinical and clinical assessment of new molecular entities and biologics in adults.

Safety of Antithrombotic Agents in Elderly Patients with Acute Coronary Syndromes

There are unique challenges in the treatment and prevention of acute coronary syndromes (ACS) with antithrombotics in elderly patients: elderly patients usually require multiple drugs due to comorbidities, are highly susceptible to adverse drug reactions and drug-drug interactions, may have cognitive problems affecting compliance and complications, are especially exposed to the risk of falls and, most importantly, ageing is an independent risk factor for bleeding. Antithrombotic drugs, alone or in association, further and variously amplify age-related bleeding risk. Moreover, age-related changes in primary haemostasis may potentially affect the pharmacodynamics of some antiplatelet drugs. Thus, elderly subjects might be more or less sensitive to standard antiplatelet regimens depending on individual characteristics affecting antiplatelet drug response. Importantly, elderly patients are a rapidly growing population worldwide, have the highest incidence of ACS, but are poorly represented in clinical trials. As a consequence, evidence on antithrombotic drug benefits and risks is limited. Thus, in the real-world setting, older people are often denied antithrombotic drugs because of unjustified concerns, or might be over-treated and exposed to excessive bleeding risk. Personalized antithrombotic therapy in elderly patients is particularly critical, to minimize risks without affecting efficacy.

Antibiothérapie du sujet âgé : On peut toujours mieux faire

Antimicrobials are among the most prescribed drugs and their prescription increases with age, due to frailty and accrued risk factors for acquiring infections. Antimicrobial prescription in elderly patients must not only account for the risk of toxicity due to drug overexposure, but also of treatment failure or promotion of antimicrobial resistance due to under-dosage. This paper reviews the main antimicrobial, pharmacokinetic and pharmacodynamic variations induced by aging, comorbidities and polypharmacy, and how to take them into account to optimize antimicrobial prescription in elders.

Rifapentine for the treatment of latent tuberculosis

INTRODUCTION

The goal of this article is to review the use of rifapentine in the treatment of latent tuberculosis infection (LTBI). Controlling LTBI is an important part of the global strategy to end the spread of tuberculosis. Rifapentine's potent sterilizing effect against Mycobacterium tuberculosis combined with its long half-life make it an attractive LTBI treatment option. Areas covered: A systematic literature search of Pubmed using the terms 'rifapentine' and 'tuberculosis' was performed. Articles identified were cross-referenced for other relevant publications. The mechanisms of action and resistance, pharmacokinetic and pharmacodynamics, potential drug interactions and side effects are discussed. Expert commentary: Rifapentine in combination with isoniazid for twelve weeks is the best available option for treating latent TB in the majority of patients in the United States due to its favorable safety profile and the increased likelihood of completing therapy. Currently, rifapentine is not registered or available in other countries.

Changes in Pharmacokinetics and Pharmacodynamics in the Elderly Patient

The use of pharmacologic agents in elderly patients is one of the most difficult aspects of patient care. An understanding of the common physiologic changes expected with aging is helpful to anticipate changes expected in pharmacokinetic parameters. Distribution, metabolism, and excretion are significantly altered for many drugs. In addition, pharmacodynamic variations in elderly patients may increase or decrease sensitivity to a medication independent of pharmacokinetic changes. These alterations are particularly noteworthy with cardiovascular and central nervous system agents. Current controversies regarding the application of estimation of renal function to drug dosing and use of the Beers criteria of medications potentially inappropriate in the elderly are discussed.

Ontogeny of plasma proteins, albumin and binding of diazepam, cyclosporine, and deltamethrin

BACKGROUND

To characterize the ontogeny of plasma albumin and total proteins, due to the lack of a comprehensive pediatric database. Secondly, to establish the magnitude and duration of maturational changes in binding of highly-bound drugs/chemicals.

METHODS

Anonymized plasma samples from 296 donors were pooled in 6 age brackets from birth to adolescence. Total protein and albumin levels were measured in each age group, as was the age-dependency of plasma binding of diazepam (DZP), cyclosporine (CYC), and deltamethrin (DLM), a pyrethroid insecticide.

RESULTS

Plasma levels of albumin and total proteins steadily increased for the first 1-3 y of life. Unbound DZP and CYC fractions were elevated three- to fourfold in neonates, but decreased to adult levels after 1 and 3 y, respectively. Unbound DLM levels exceeded those in adults for just 1 mo.

CONCLUSION

Neonates and infants under 1-3 y may be at risk from increased amounts of free drug, when given standard doses of some highly-bound drugs. Pyrethroid insecticides might be anticipated to pose increased risk for 1 mo.

Elderly patients' participation in clinical trials

The elderly population is a large and the fastest-growing portion of the population worldwide. The elderly make up the lion's share of patients for certain health conditions including cancer, cardiovascular disease, arthritis, and Parkinson's disease, among others in most parts of the world. Furthermore, elderly make up the majority of patients for many medications treating chronic conditions. Typically, clinical trials conducted in adult population include patients between the ages of 18 and 64 years. However, drugs should be studied in all age groups and trial participants should be representative of the patient population receiving the therapy in daily medical practice. Elderly patients are poorly represented in clinical trials. Hence, there is inadequate evidence and knowledge about responses of geriatric patients to medications. Regulatory authorities in developed countries urge to avoid arbitrary upper age limits and advise researchers and industry not to exclude elderly people from clinical trials without a valid reason. Since last few years Indian regulatory authority has been stipulating upper age limit for studies conducted in India. The Central Drugs Standard Control Organization (CDSCO) will be doing a great contribution to the researchers if it changes its view on stipulating upper age restrictions in clinical studies. This article describes the need for including elderly patients in the clinical trials in order to garner data from geriatric patients who form major medication users in most of the chronic diseases.

Normalized vitamin D metabolite concentrations are better correlated to pharmacological effects than measured concentrations

Background:

Vitamin D deficiency has been associated with a multitude of diseases, ranging from fractures to cancer. Nearly 99% of vitamin D metabolites are bound to proteins, altering the relationship between concentration and activity.

Methods & results:

Normalized concentrations were calculated and validated using published data regarding the correlation of 25-hydroxyvitamin D with bone mineral density. In addition, healthy and kidney disease subjects were recruited for preliminary investigations. Use of the normalizing equations resulted in statistically significant improvements in the relationship between vitamin D metabolites and several markers of health status.

Conclusion:

Normalized concentrations are similar to clinically reported values and are easier to interpret than free or bioavailable concentrations, since their values match the range of measured total concentrations.

Lay abstract: Vitamin D deficiency has been associated with a multitude of diseases, ranging from fractures to cancer. Most vitamin D metabolites are bound to various body components, altering the relationship between reported concentration and biological effects. To compensate for differences in binding between individuals, normalized concentrations were calculated. Use of the normalizing equations resulted in significant improvements in the relationship between the concentration of vitamin D metabolites and health status. The newly developed normalized concentrations are therefore better indicators of vitamin D status and are easier to interpret than free or bioavailable concentrations, since their values match the range of measured total concentrations.

Artocarpin Induces Apoptosis in Human Cutaneous Squamous Cell Carcinoma HSC-1 Cells and Its Cytotoxic Activity Is Dependent on Protein-Nutrient Concentration

Artocarpin, a natural prenylated flavonoid, has been shown to have various biological properties. However, its effects on human cutaneous squamous cell carcinoma (SCC) have not been previously investigated. We set out to determine whether artocarpin has cytotoxic effects on SCC cells and whether its pharmacological activity is dependent on protein-nutrient concentration. Our results showed that treatment of HSC-1 cells (a human cutaneous SCC cell line) with artocarpin decreased cell viability and induced cell apoptosis by increasing caspase 3/7 activity. These effects were more pronounced at low fetal bovine serum (FBS) concentrations. Artocarpin induced an increase in the level of phospho-p38 and a decrease in the levels of phospho-ERK, phospho-JNK, phospho-Akt, phospho-mTOR, and phospho-S6K. High FBS concentrations in the culture media inhibited and delayed the uptake of artocarpin from the extracellular compartment (culture media) into the intracellular compartment, as determined by high performance liquid chromatography (HPLC) analysis. In conclusion, artocarpin induces apoptosis in HSC-1 cells through modulation of MAPK and Akt/mTOR pathways. Binding of artocarpin to proteins in the FBS may inhibit cellular uptake and reduce the cytotoxic activity of artocarpin on HSC-1 cells. Therefore, artocarpin may have potential use in the future as a form of treatment for cutaneous SCC.