The influence of circadian rhythms on the kinetics of drugs in humans

Chrono-tailored drug delivery systems: recent advances and future directions

Circadian rhythms influence a range of biological processes within the body, with the central clock or suprachiasmatic nucleus (SCN) in the brain synchronising peripheral clocks around the body. These clocks are regulated by external cues, the most influential being the light/dark cycle, in order to synchronise with the external day. Chrono-tailored or circadian drug delivery systems (DDS) aim to optimise drug delivery by releasing drugs at specific times of day to align with circadian rhythms within the body. Although this approach is still relatively new, it has the potential to enhance drug efficacy, minimise side effects, and improve patient compliance. Chrono-tailored DDS have been explored and implemented in various conditions, including asthma, hypertension, and cancer. This review aims to introduce the biology of circadian rhythms and provide an overview of the current research on chrono-tailored DDS, with a particular focus on immunological applications and vaccination. Finally, we draw on some of the key challenges which need to be overcome for chrono-tailored DDS before they can be translated to more widespread use in clinical practice.

Identifying novel mechanisms of per- and polyfluoroalkyl substance-induced hepatotoxicity using FRG humanized mice

Per- and polyfluoroalkyl substances (PFAS) such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) and perfluoro-2-methyl-3-oxahexanoic acid (GenX), the new replacement PFAS, are major environmental contaminants. In rodents, these PFAS induce several adverse effects on the liver, including increased proliferation, hepatomegaly, steatosis, hypercholesterolemia, nonalcoholic fatty liver disease and liver cancers. Activation of peroxisome proliferator receptor alpha by PFAS is considered the primary mechanism of action in rodent hepatocyte-induced proliferation. However, the human relevance of this mechanism is uncertain. We investigated human-relevant mechanisms of PFAS-induced adverse hepatic effects using FRG liver-chimeric humanized mice with livers repopulated with functional human hepatocytes. Male FRG humanized mice were treated with 0.067 mg/L of PFOA, 0.145 mg/L of PFOS, or 1 mg/L of GenX in drinking water for 28 days. PFOS caused a significant decrease in total serum cholesterol and LDL/VLDL, whereas GenX caused a significant elevation in LDL/VLDL with no change in total cholesterol and HDL. All three PFAS induced significant hepatocyte proliferation. RNA-sequencing with alignment to the human genome showed a total of 240, 162, and 619 differentially expressed genes after PFOA, PFOS, and GenX exposure, respectively. Upstream regulator analysis revealed that all three PFAS induced activation of p53 and inhibition of androgen receptor and NR1D1, a transcriptional repressor important in circadian rhythm. Further biochemical studies confirmed NR1D1 inhibition and in silico modeling indicated potential interaction of all three PFAS with the DNA-binding domain of NR1D1. In conclusion, our studies using FRG humanized mice have revealed new human-relevant molecular mechanisms of PFAS including their previously unknown effect on circadian rhythm.

Dosing-time, feeding, and sex-dependent variations of everolimus pharmacokinetics in mice

BACKGROUND

Everolimus is an oral mammalian target of rapamycin (mTOR) inhibitor used as an immunosuppressant and anticancer. Its pharmacokinetics is highly variable, it has a narrow therapeutic window and shows chronotoxicity with the best time at ZT13 and worst time at ZT1 (ZT; Zeitgeber time, time after light onset) in the preclinical setting.

OBJECTIVES

In the present study, we aimed to investigate whether the pharmacokinetics of everolimus vary according to dosing time and whether sex and feeding status interfere with the chronopharmacokinetics.

METHOD

A single dosage of 5 mg/kg everolimus was administered orally to C57BL/6J male and female mice, in fed or fasted states at ZT1-rest and ZT13-activity times and blood and tissue samples were collected at 0.5, 1, 2, 4, 12, and 24 h following drug administration. Ileum, liver, plasma, and thymus concentrations of everolimus were determined.

RESULTS

Females had a greater ileum AUC0-24h than males when fed (P = 0.043). Everolimus AUC0-24h in the liver was substantially greater at ZT1 than at ZT13 in a fasted state (P = 0.001). Plasma Cmax , AUC0-24h , and AUCtotal were not statistically significant between the groups (P = 0.098). In one of the target organs of everolimus, the thymus, males had considerably higher amounts at ZT1 than females (P = 0.029).

CONCLUSION

Our findings imply that the pharmacokinetics of everolimus in mice may differ according to dosing time, sex, and feeding. Greater tissue distribution of everolimus at ZT1 may be associated with the worst tolerated time of everolimus. Our research suggests that oral chronomodulated everolimus therapy may be more effective and safer for cancer patients.

Chronopharmacology of diuresis via metabolic profiling and key biomarker discovery of the traditional Chinese prescription Ji-Ming-San using tandem mass spectrometry in rat models

BACKGROUND

Ji-Ming-Shan (JMS) is a traditional prescription used for patients with rheumatism, tendons swelling, relief of foot pain, athlete's foot, diuresis, gout. Although many studies have investigated the active compounds in each herb, the functional mechanism behind its therapeutic effect remains unclear.

STUDY DESIGN

Metabolic cages for sample collection. The serum components obtained from the experimental animals were analyzed using LC-MS/MS. Furthermore, cross-analysis using the software MetaboAnalyst and Venn diagrams were used to investigate chronopharmacology of JMS in the animal models.

PURPOSE

The aim of this study is to analyze the diuretic effects of JMS and to explore their chronopharmacology involved in organ regulation through four-quarter periods from serum samples of rat models.

METHODS

Metabolic cages were used for collecting the urine samples and PocketChem UA PU-4010, Fuji DRI-CHEM 800 were used to examine the urine biochemical parameters. The serum components were identified through ultra-performance liquid chromatography-quadrupole time-of-flight (UPLC-Q-TOF) with a new developed method. Cross analysis, Venn diagram, MetaboAnalyst were used to investigate the key biomarker and major metabolism route with the oral administration of the drug.

RESULT

JMS significantly changed the 6 h urine volume with no observed kidney toxicity. Urine pH value ranges from 7.0 to 7.5. The chronopharmacology of JMS diuresis activity were 0-6 and 6-12 groups. UPLC-Q-TOF analyses identified 243 metabolites which were determined in positive mode and negative mode respectively. With cross analysis in the Venn diagram, one key biomarker naringenin-7-O-glucoside has been identified. Major metabolic pathways such as 1: Glycerophospholipid metabolism, 2: Primary bile acid biosynthesis, 3: Sphingolipid metabolism, 4: Riboflavin metabolism, 5: Linoleic acid metabolism, 6: Butanoate metabolism.

CONCLUSION

JMS significantly changed the urine output of animals in the 0-6 and 6-12 groups. No change in urine pH was observed and also kidney toxicity. A new UPLC-Q-TOF method was developed for the detection of the metabolites of JMS after oral administration. The cross analysis with Venn diagram and identified the key biomarker of JMS namely naringenin-7-O-glucoside. The results showed that six major pathways are involved in the gastrointestinal system and the liver. This study demonstrated the capability of JMS prescription in the regulation of diuresis and identified a key biomarker that is responsible for its therapeutic effect.

Clinical trial design for assessing hypertension medications: are critical circadian chronopharmacological principles being taking into account?

INTRODUCTION

Clinical hypertension trials typically rely on homeostatic principles, including single time-of-day office blood pressure (BP) measurements (OBPM), rather than circadian chronopharmacological principles, including ambulatory monitoring (ABPM) done around-the-clock to derive the asleep systolic BP (SBP) mean and sleep-time relative SBP decline - jointly the strongest prognosticators of cardiovascular disease (CVD) risk and true definition of hypertension - to qualify participants and assess outcomes.

AREAS COVERED

Eight chronopharmacological elements are indispensable for design and conduct of hypertension medication trials, mainly those on ingestion-time differences in effects, and also a means of rating quality of investigations. Accordingly, we highlight the findings and shortcomings of: (i) 155 such ingestion-time trials, 83.9% finding at-bedtime/evening treatment more beneficial than conventional upon-awakening/morning treatment; (ii) HOPE and ONTARGET CVD outcomes investigations assessing in the former add-on ramipril at-bedtime and in the latter telmisartan, ramipril, or both in combination in the morning; and (iii) pragmatic TIME CVD outcomes trial.

EXPERT OPINION

Failure to incorporate chronopharmacological principals - including ABPM to derive asleep SBP and SBP dipping to qualify subjects as hypertensive and assess CVD risk - results in deficient study design, dubious findings, and unnecessary medical controversy at the expense of advances in patient care.

The Physiological and Pharmacological Significance of the Circadian Timing of the HPA Axis: A Mathematical Modeling Approach

As a potent endogenous regulator of homeostasis, the circadian time-keeping system synchronizes internal physiology to periodic changes in the external environment to enhance survival. Adapting endogenous rhythms to the external time is accomplished hierarchically with the central pacemaker located in the suprachiasmatic nucleus (SCN) signaling the hypothalamus-pituitary-adrenal (HPA) axis to release hormones, notably cortisol, which help maintain the body's circadian rhythm. Given the essential role of HPA-releasing hormones in regulating physiological functions, including immune response, cell cycle, and energy metabolism, their daily variation is critical for the proper function of the circadian timing system. In this review, we focus on cortisol and key fundamental properties of the HPA axis and highlight their importance in controlling circadian dynamics. We demonstrate how systems-driven, mathematical modeling of the HPA axis complements experimental findings, enhances our understanding of complex physiological systems, helps predict potential mechanisms of action, and elucidates the consequences of circadian disruption. Finally, we outline the implications of circadian regulation in the context of personalized chronotherapy. Focusing on the chrono-pharmacology of synthetic glucocorticoids, we review the challenges and opportunities associated with moving toward personalized therapies that capitalize on circadian rhythms.

Hypnotic effects of melatonin depend on the environmental lighting conditions in the rat

Acute effects of exogenous melatonin have been widely reported to promote sleep or induce drowsiness in human. However, testing of the hypnotic effects of melatonin in nocturnal rodents has yielded contradictory results. The latter may be associated with differences in concentration, lighting conditions, time of administration of melatonin, and possibly the type of analysis. In this study, electroencephalogram (EEG) and electromyogram were recorded in pigmented male Brown Norway rats under both light-dark (LD) and constant dark (DD) conditions. Melatonin was administered intraperitoneally at a moderate dose of 3 mg/kg, at either 1 h after lights on under LD condition or 1 h after the activity offset under DD condition. The dosage is known to be able to entrain nocturnal rodents in DD conditions, but does not change sleep in rodents in LD. Only the rats under DD conditions showed a significant reduction in nonrapid eye movement (NREM) sleep latency, while the NREM sleep power spectrum remained unaffected. Under LD condition, melatonin did not alter NREM and rapid eye movement (REM) sleep latency, and had only minor effects on the NREM sleep EEG. Regardless of lighting conditions, melatonin administration resulted in less, but longer episodes for all vigilance states suggesting increased vigilance state consolidation. In the discussion, we compare our results with a summary of previously published data concerning the hypnotic effects of melatonin in polysomnographic/EEG-confirmed sleep in humans and nocturnal rodents. In conclusion, the hypnotic effect of exogenous melatonin in nocturnal rodents not only depends on the time of day, and concentration, but is also influenced by the lighting conditions. Regardless of inducing sleep or not, melatonin may consolidate sleep and through that enhance sleep quality.

Population pharmacokinetics of mycophenolic acid and dose optimisation in adult Chinese kidney transplant recipients

1. This study aimed to establish a population pharmacokinetic (PPK) model of mycophenolic acid (MPA), quantify the effect of clinical factors and pharmacogenomics of MPA, and optimise the dosage for adult kidney transplant recipients.2. One-hundred and four adult renal transplant patients were enrolled. The PPK model was established using the Phoenix® NMLE software and the stepwise methods were filtered for significant covariates. Monte Carlo simulations were performed to optimise the dosage regimen.3. A two-compartment model with first-order absorption and elimination (including lag time) provided a more accurate description of MPA pharmacokinetics. Serum albumin (ALB) significantly affected the central apparent clearance (CL/F), whereas post-transplant time and creatinine clearance were associated with a central apparent volume of distribution (V/F). The estimated population values obtained by the final model were 17.5 L/h and 93.97 L for CL/F and V/F, respectively. Simulation results revealed that larger mycophenolate mofetil doses are required as the ALB concentration decreases. This study established a PPK model of MPA and validated it using various methods. ALB significantly affected CL/F and recommended optimal dose strategies were given based on the final model. These results provide a reference for the personalised therapy of MPA for kidney transplant patients.

Chrono-modulated effects of external stressors on oxidative stress and damage in humans: A scoping review on night shift work

BACKGROUND

Oxidative stress and tissue damage (OSD) play a pivotal role as an early-stage process in chronic disease pathogenesis. However, there has been little research to better understand the temporal (χρόνος[chronos]) dimensions of OSD process associated with environmental (non-genetic, including behaviors/lifestyle) and/or occupational stressors, like night shift work. OSD processes have recently attracted attention in relation to time-resolved external stressor trajectories in personalized medicine (prevention) initiatives, as they seem to interact with circadian clock systems towards the improved delineation of the early stages of (chronic) disease process.

OBJECTIVES

This work critically reviewed human studies targeting the temporal dynamics of OSD and circadian clock system's activity in response to environmental/occupational stressors; the case of night shift work was examined.

METHODS

Being a key stressor influencing OSD processes and circadian rhythm, night shift work was evaluated as part of a scoping review of research in OSD, including inflammatory and metabolic processes to determine the extent of OSD research undertaken in human populations, methodologies, tools and biomarkers used and the extent that the temporal dimensions of exposure and biological effect(s) were accounted for. Online databases were searched for papers published from 2000 onwards, resulting in the selection of 53 original publications.

RESULTS AND DISCUSSION

The majority of studies (n = 41) took place in occupational settings, while the rest were conducted in the general population or patient groups. Most occupational studies targeted outcomes of oxidative stress/damage (n = 19), followed by the combination of OSD with inflammatory response (n = 10), and studies focused on metabolic outcomes (n = 12). Only a minor fraction of the studies measured biomarkers related to circadian rhythm, such as, melatonin, its metabolite, or cortisol. Night shift work was associated with select biomarkers of OSD and inflammation, albeit with mixed results. Although much progress in delineating the biological mechanisms of OSD process has been made, an equally thorough investigation on the temporal trajectory of OSD processes as triggered by environmental/occupational stressors in human studies has yet to fully evolve.

Understanding the role of chronopharmacology for drug optimization: what do we know?

INTRODUCTION

Circadian rhythm influences the pharmacokinetics and pharmacodynamics of a number of drugs and affects their therapeutic efficacy and toxicity depending on the time of day they are administered. Chronopharmacology is a method for incorporating knowledge about circadian rhythm into pharmacotherapy. Chronotherapy, which is the clinical application of chronopharmacology, is particularly relevant when the risk and/or severity of symptoms of a disease change in a predictable manner over time. Chronotherapy has potential benefits in the treatment of many diseases.

AREAS COVERED

Although a considerable amount of knowledge about chronopharmacology and chronotherapy has been accumulated, its therapeutic application in clinical practice remains limited in terms of therapy optimization. Resolution of these issues will improve our ability to deliver adequate drug treatment.

EXPERT OPINION

We propose four approaches for promoting chronotherapy-based drug treatment in clinical practice: targeting drug development and regulatory authorities; education about chronotherapy; drug information for both health professionals and consumers; and a chronotherapy network.

Circadian Regulator-Mediated Molecular Subtypes Depict the Features of Tumor Microenvironment and Indicate Prognosis in Head and Neck Squamous Cell Carcinoma

Introduction

Circadian rhythm is involved in multiple biological activities and implicated in cancer development. However, the role of circadian rhythm in head and neck squamous cell carcinoma (HNSCC) has not been fully interpreted yet. Herein, the present study set out to explore the significance of circadian regulator genes (CRGs) in HNSCC.

Materials and Methods

The molecular landscape and clinical significance of 13 CRGs in HNSCC were explored based on The Cancer Genome Atlas (TCGA). The biological functions of PER3, a key CRG, were validated by cellular experiments. The correlation of CRGs with microenvironment, pathway activities, and prognosis was determined by bioinformatic algorithms. A novel circadian score was introduced to evaluate the circadian modification pattern of each patient and further validated in an independent cohort from the Gene Expression Omnibus (GEO) dataset.

Results

CRGs presented high heterogeneity in HNSCC at both genomic and transcriptomic levels. Specifically, PER3 indicated a better prognosis and inhibited HNSCC cell proliferation. Moreover, HNSCC tissues displayed three circadian regulator patterns with distinct clinical outcomes, transcriptomic characteristics, and microenvironment features. Circadian score was an independent risk factor and exhibited excellent predictive efficiency in both the training cohort from the TCGA database and the validation cohort from the GEO database.

Conclusions

CRGs played an indispensable role in HNSCC development. An in-depth exploration of circadian rhythm would improve the understanding of HNSCC carcinogenesis and confer novel insights for future clinical practices.

Identifying Human Specific Adverse Outcome Pathways of Per- and Polyfluoroalkyl Substances Using Liver-Chimeric Humanized Mice

Background

Per- and polyfluoroalkyl substances (PFAS) are persistent organic pollutants with myriad adverse effects. While perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) are the most common contaminants, levels of replacement PFAS, such as perfluoro-2-methyl-3-oxahexanoic acid (GenX), are increasing. In rodents, PFOA, PFOS, and GenX have several adverse effects on the liver, including nonalcoholic fatty liver disease.

Objective

We aimed to determine human-relevant mechanisms of PFAS induced adverse hepatic effects using FRG liver-chimeric humanized mice with livers repopulated with functional human hepatocytes.

Methods

Male humanized mice were treated with 0.067 mg/L of PFOA, 0.145 mg/L of PFOS, or 1 mg/L of GenX in drinking water for 28 days. Liver and serum were collected for pathology and clinical chemistry, respectively. RNA-sequencing coupled with pathway analysis was used to determine molecular mechanisms.

Results

PFOS caused a significant decrease in total serum cholesterol and LDL/VLDL, whereas GenX caused a significant elevation in LDL/VLDL with no change in total cholesterol and HDL. PFOA had no significant changes in serum LDL/VLDL and total cholesterol. All three PFAS induced significant hepatocyte proliferation. RNA-sequencing with alignment to the human genome showed a total of 240, 162, and 619 differentially expressed genes after PFOA, PFOS, and GenX exposure, respectively. Upstream regulator analysis revealed inhibition of NR1D1, a transcriptional repressor important in circadian rhythm, as the major common molecular change in all PFAS treatments. PFAS treated mice had significant nuclear localization of NR1D1. In silico modeling showed PFOA, PFOS, and GenX potentially interact with the DNA-binding domain of NR1D1.

Discussion

These data implicate PFAS in circadian rhythm disruption via inhibition of NR1D1. These studies show that FRG humanized mice are a useful tool for studying the adverse outcome pathways of environmental pollutants on human hepatocytes in situ.

Circadian rhythms of risk factors and management in atherosclerotic and hypertensive vascular disease: Modern chronobiological perspectives of an ancient disease

Atherosclerosis, a chronic inflammatory disease of the arteries that appears to have been as prevalent in ancient as in modern civilizations, is predisposing to life-threatening and life-ending cardiac and vascular complications, such as myocardial and cerebral infarctions. The pathogenesis of atherosclerosis involves intima plaque buildup caused by vascular endothelial dysfunction, cholesterol deposition, smooth muscle proliferation, inflammatory cell infiltration and connective tissue accumulation. Hypertension is an independent and controllable risk factor for atherosclerotic cardiovascular disease (CVD). Conversely, atherosclerosis hardens the arterial wall and raises arterial blood pressure. Many CVD patients experience both atherosclerosis and hypertension and are prescribed medications to concurrently mitigate the two disease conditions. A substantial number of publications document that many pathophysiological changes caused by atherosclerosis and hypertension occur in a manner dependent upon circadian clocks or clock gene products. This article reviews progress in the research of circadian regulation of vascular cell function, inflammation, hemostasis and atherothrombosis. In particular, it delineates the relationship of circadian organization with signal transduction and activation of the renin-angiotensin-aldosterone system as well as disturbance of the sleep/wake circadian rhythm, as exemplified by shift work, metabolic syndromes and obstructive sleep apnea (OSA), as promoters and mechanisms of atherogenesis and risk for non-fatal and fatal CVD outcomes. This article additionally updates advances in the clinical management of key biological processes of atherosclerosis to optimally achieve suppression of atherogenesis through chronotherapeutic control of atherogenic/hypertensive pathological sequelae.

Understanding the dosing-time-dependent antihypertensive effect of valsartan and aspirin through mathematical modeling

Chronopharmacology of arterial hypertension impacts the long-term cardiovascular risk of hypertensive subjects. Therefore, clinical and computational studies have proposed optimizing antihypertensive medications' dosing time (Ta). However, the causes and mechanisms underlying the Ta-dependency antihypertensive effect have not been elucidated. Here we propose using a Ta- dependent effect model to understand and predict the antihypertensive effect of valsartan and aspirin throughout the day in subjects with grade I or II essential hypertension. The model based on physiological regulation mechanisms includes a periodic function for each parameter that changes significantly after treatment. Circadian variations of parameters depending on the dosing time allowed the determination of regulation mechanisms dependent on the circadian rhythm that were most relevant for the action of each drug. In the case of valsartan, it is the regulation of vasodilation and systemic vascular resistance. In the case of aspirin, the antithrombotic effect generates changes in the sensitivity of systemic vascular resistance and heart rate to changes in physical activity. Dosing time-dependent models predict a more significant effect on systemic vascular resistance and blood pressure when administering valsartan or aspirin at bedtime. However, circadian dependence on the regulation mechanisms showed different sensitivity of their circadian parameters and shapes of functions, presenting different phase shifts and amplitude. Therefore, different mechanisms of action and pharmacokinetic properties of each drug can generate different profiles of Ta-dependence of antihypertensive effect and optimal dosing times.

A time differentiated dietary intervention effect on the biomarkers of exposure to pyrethroids and neonicotinoids pesticides

Tailoring medical models to the right person or risk subgroups delivered at the right time is important in personalized medicine/prevention initiatives. The CIRCA-CHEM randomized 2x2 crossover pilot trial investigated whether the consumption of fruits/vegetables within a time-restricted daily window would affect urinary biomarkers of exposure to neonicotinoids (6-chloronicotinic acid, 6-CN) and pyrethroids (3-phenoxybenzoic acid, 3-PBA) pesticides, a biomarker of oxidative damage (4-hydroxynonenal, 4-HNE) and the associated urinary NMR metabolome. A statistically significant difference (p < 0.001) in both creatinine-adjusted 6-CN and 3-PBA levels was observed between the two-time dietary intervention windows (morning vs. evening). In the evening intervention period, pesticides biomarker levels were higher compared to the baseline, whereas in the morning period, pesticide levels remained unchanged. Positive associations were observed between pesticides and 4-HNE suggesting a diurnal chrono-window of pesticide toxicity. The discovery of a chronotoxicity window associated with chrono-disrupted metabolism of food contaminants may find use in personalized medicine initiatives.

Neurodegenerative diseases and blood pressure variability: A comprehensive review from HOPE Asia

Asia has an enormous number of older people and is the primary contributor to the rise in neurodegenerative diseases such as Alzheimer's and Parkinson's disease. The therapy of many neurodegenerative diseases has not yet progressed to the point where it is possible to alter the course of the disease. Mid-life hypertension is an important predictor of later-life cognitive impairment and brain neurodegenerative conditions. These findings highlight the pivotal role of preventing and managing hypertension as a risk factor for neurodegenerative disease. Autonomic dysfunction, neuropsychiatric and sleep disturbances can arise in neurodegenerative diseases, resulting in blood pressure variability (BPV). The BPV itself can worsen the progression of the disease. In older people with neurodegenerative disease and hypertension, it is critical to consider 24-h blood pressure monitoring and personalized blood pressure therapy.

Recent advances in circadian-regulated pharmacokinetics and its implications for chronotherapy

Dependence of pharmacokinetics and drug effects (efficacy and toxicity) on dosing time has long been recognized. However, significant progress has only recently been made in our understanding of circadian rhythms and their regulation on drug pharmacokinetics, efficacy and toxicity. This review will cover the relevant literature and a series of publications from our work summarizing the effects of circadian rhythms on drug pharmacokinetics, and propose that the influence of circadian rhythms on pharmacokinetics are ultimately translated into therapeutic effects and side effects of drugs. Evidence suggests that daily rhythmicity in expression of drug-metabolizing enzymes and transporters necessary for drug ADME (absorption, distribution, metabolism and excretion) are key factors determining circadian pharmacokinetics. Newly discovered mechanisms for circadian control of the enzymes and transporters are covered. We also discuss how the rhythms of drug-processing proteins are translated into circadian pharmacokinetics and drug chronoefficacy/chronotoxicity, which has direct implications for chronotherapy. More importantly, we will present perspectives on the challenges that are still needed for a breakthrough in translational research. In addition, knowledge of the circadian influence on drug disposition has provided new possibilities for novel pharmacological strategies. Careful application of pharmacokinetics-based chronotherapy strategies can improve efficacy and reduce toxicity. Circadian rhythm-mediated metabolic and transport strategies can also be implemented to design drugs.

A Phase 1, Open-Label Study to Evaluate the Effects of Food and Evening Dosing on the Pharmacokinetics of Oral Trofinetide in Healthy Adult Subjects

Background and Objective

Trofinetide, a synthetic analog of tripeptide glycine-proline-glutamate, is an investigational agent for the treatment of Rett syndrome, a neurodevelopmental disorder with affected individuals requiring lifelong support. Food can affect the pharmacokinetic profile of a drug, and this phase 1 study assessed the potential effect of food on the pharmacokinetics of trofinetide. The study also evaluated the potential effect of evening dosing on trofinetide bioavailability and characterized the pharmacokinetic profile of trofinetide in urine.

Methods

A 60 mL oral solution of trofinetide (12 g) was administered in three dosing periods: morning fasted (A; reference), morning fed (B), and evening fasted (C). Healthy adult subjects (18−45 years) were randomized to sequence ABC (n = 19) or BAC (n = 22). Blood and urine samples were collected at scheduled timepoints for trofinetide pharmacokinetic analysis. Bioequivalence was confirmed if 90% confidence intervals for geometric mean ratio between B/A or C/A fell within 80–125% equivalence limits for area under the concentration-time curve (AUC) and maximum concentration (C_max) in whole blood.

Results

Bioequivalence criteria were met for all conditions (i.e., morning fed vs. morning fasted and evening fasted vs. morning fasted) except C_max in the fed versus fasted condition, which was just below the bioequivalence limit (75.49%), suggesting a negligible food effect and lack of diurnal variation on bioavailability. Trofinetide was primarily excreted unchanged in urine. Trofinetide was well tolerated, and there were no significant changes in vital signs or laboratory parameters.

Conclusion

This study supports dosing of trofinetide without regard to food.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40261-022-01156-4.

The circadian rhythm of viruses and its implications on susceptibility to infection

INTRODUCTION

Circadian genes have an impact on multiple hormonal, metabolic, and immunological pathways and have recently been implicated in some infectious diseases.

AREAS COVERED

We review aspects related to the current knowledge about circadian rhythm and viral infections, their consequences, and the potential therapeutic options.

EXPERT OPINION

Expert opinion: In order to address a problem, it is necessary to know the topic in depth. Although in recent years there has been a growing interest in the role of circadian rhythms, many relevant questions remain to be resolved. Thus, the mechanisms linking the circadian machinery against viral infections are poorly understood. In a clear approach to personalized precision medicine, in order to treat a disease in the most appropriate phase of the circadian rhythm, and in order to achieve the optimal efficacy, it is highly recommended to carry out studies that improve the knowledge about the circadian rhythm.

The Daily Expression of ABCC4 at the BCSFB Affects the Transport of Its Substrate Methotrexate

The choroid plexuses (CPs), located in the brain ventricles, form an interface between the blood and the cerebrospinal fluid named the blood-cerebrospinal barrier, which, by the presence of tight junctions, detoxification enzymes, and membrane transporters, limits the traffic of molecules into the central nervous system. It has already been shown that sex hormones regulate several CP functions, including the oscillations of its clock genes. However, it is less explored how the circadian rhythm regulates CP functions. This study aimed to evaluate the impact of sex hormones and circadian rhythms on the function of CP membrane transporters. The 24 h transcription profiles of the membrane transporters rAbca1, rAbcb1, rAbcc1, rAbcc4, rAbcg2, rAbcg4, and rOat3 were characterized in the CPs of intact male, intact female, sham-operated female, and gonadectomized rats. We found that rAbcc1 is expressed in a circadian way in the CPs of intact male rats, rAbcg2 in the CPs of intact female rats, and both rAbcc4 and rOat3 mRNA levels were expressed in a circadian way in the CPs of intact male and female rats. Next, using an in vitro model of the human blood–cerebrospinal fluid barrier, we also found that methotrexate (MTX) is transported in a circadian way across this barrier. The circadian pattern of Abcc4 found in the human CP epithelial papilloma cells might be partially responsible for MTX circadian transport across the basal membrane of CP epithelial cells.

Pharmacogenomics and circadian rhythms as mediators of cardiovascular drug-drug interactions

This article summarizes the current literature and documents new evidence concerning drug-drug interactions (DDI) stemming from pharmacogenomic and circadian rhythm determinants of therapies used to treat common cardiovascular diseases (CVD), such as atherosclerosis and hypertension. Patients with CVD often have more than one pathophysiologic condition, namely metabolic syndromes, hypertension, hyperlipidemia, and hyperglycemia, among others, which necessitate polytherapeutic or polypharmaceutic management. Interactions between drugs, drugs and food/food supplements, or drugs and genetic/epigenetic factors may have adverse impacts on the cardiovascular and other systems of the body. The mechanisms underlying cardiovascular DDI may involve the formation of a complex pharmacointeractome, including the absorption, distribution, metabolism, and elimination of drugs, which affect their respective bioavailability, efficacy, and/or harmful metabolites. The pharmacointeractome of cardiovascular drugs is likely operated with endogenous rhythms controlled by circadian clock genes. Basic and clinical investigations have improved the knowledge and understanding of cardiovascular pharmacogenomics and pharmacointeractomes, and additionally they have presented new evidence that the staging of deterministic circadian rhythms, according to the dosing time of drugs, e.g., upon awakening vs. at bedtime, cannot only differentially impact their pharmacokinetics and pharmacodynamics but also mediate agonistic/synergetic or antagonistic DDI. To properly manage CVD patients and avoid DDI, it is important that clinicians have sufficient knowledge of their multiple risk factors, i.e., age, gender, and life style elements (like diet, smoking, psychological stress, and alcohol consumption), and comorbidities, such as diabetes, hypertension, dyslipidemia, and depression, and the potential interactions between genetic or epigenetic background of their prescribed therapeutics.

Ingestion-time differences in the pharmacodynamics of dual-combination hypertension therapies: Systematic review and meta-analysis of published human trials

The pharmacodynamics of hypertension medications can be significantly affected by circadian rhythms in the biological mechanisms of the 24 h blood pressure (BP) pattern. Hypertension guidelines fail to recommend the time of day when patients, including those who require treatment with multiple medications, are to ingest BP-lowering therapy. We conducted a systematic review of published prospective trials that investigated hypertension medications for ingestion-time differences in BP-lowering, safety, patient adherence, and markers of target organ pathology. Among the search-retried 155 trials, 17 published between 1991 and 2020 totaling 1,508 hypertensive participants concerned the differential ingestion-time dependent effects of 14 unique dual-combination therapies. All but one (94.1%) of the trials, involving 98.5% of the total number of investigated individuals, reported clinically and statistically significant benefits - including enhanced reduction of asleep BP without induction of sleep-time hypotension, reduced prevalence of BP non-dipping, decreased adverse effects, improved kidney function, and reduced cardiac pathology - when dual-combination hypertension medications were ingested at-bedtime/evening rather than upon-waking/morning. A systematic and comprehensive review of the literature published in the past three decades reveals no single dual-combination hypertension trial reported significantly better benefit of the still conventional, yet unjustified by medical evidence, upon-waking/morning hypertension treatment scheme.

Chronopharmacology in Therapeutic Drug Monitoring-Dependencies between the Rhythmics of Pharmacokinetic Processes and Drug Concentration in Blood

The objective of the optimization of pharmacotherapy compliant with the basic rules of clinical pharmacology is its maximum individualization, ensuring paramount effectiveness and security of the patient's therapy. Thus, multiple factors that are decisive in terms of uniqueness of treatment of the given patient must be taken into consideration, including, but not limited to, the patient's age, sex, concomitant diseases, special physiological conditions (e.g., pregnancy, lactation, extreme age groups), polypharmacotherapy and polypragmasia (particularly related to increased risk of drug interactions), and patient's phenotypic response to the administered drug with possible genotyping. Conducting therapy while monitoring the concentration of certain drugs in blood (Therapeutic Drug Monitoring; TDM procedure) is also one of the factors enabling treatment individualization. Furthermore, another material, and yet still a marginalized pharmacotherapeutic factor, is chronopharmacology, which indirectly determines the values of drug concentrations evaluated in the TDM procedure. This paper is a brief overview of chronopharmacology, especially chronopharmacokinetics, and its connection with the clinical interpretation of the meaning of the drug concentrations determined in the TDM procedure.

Desynchronized circadian clock and exposures to xenobiotics are associated with differentiated disease phenotypes: The interface of desynchronized circadian clock and exposures to xenobiotics would lead to adverse response and recovery

A paradigm shift in the human chronotoxicity of xenobiotics would study two-sided desynchronized phenomena of interfacial interactions between cyclic or periodic environmental insults and the endogenous response and recovery profile. These systems-based networks are under the influence of well-synchronized biological clocks and their metabolic regulators. This perspective argues in favor of addressing the concept of synchronization in studies involving critical life windows of susceptibility, or circadian rhythms, or 24-hour (periodic) diurnal rhythms and answering whether these disruptions in synchronization would affect response and recovery or disease phenotypes associated with environmental insults, e.g., xenobiotics. Synchronization or synchrony is defined as the totality of elements that appear during the same time period within a system, including the network of interactions between the system's elements. Desynchronized interfaces during critical life windows or in time-repeated exposure events would likely lead to initiating a cascade of adverse health effects associated with differentiated disease phenotypes.

Exploring the link between chronobiology and drug delivery: effects on cancer therapy

Circadian clock is an impressive timing system responsible for the control of several metabolic, physiological and behavioural processes. Nowadays, the connection between the circadian clock and cancer occurrence and development is consensual. Therefore, the inclusion of circadian timing into cancer therapy may potentially offer a more effective and less toxic approach. This way, chronotherapy has been shown to improve cancer treatment efficacy. Despite this relevant finding, its clinical application is poorly exploited. The conception of novel anticancer drug delivery systems and the combination of chronobiology with nanotechnology may provide a powerful tool to optimize cancer therapy, instigating the incorporation of the circadian timing into clinical practice towards a more personalized drug delivery. This review focuses on the recent advances in the field of cancer chronobiology, on the link between cancer and the disruption of circadian rhythms and on the promising targeted drug nanodelivery approaches aiming the clinical application of cancer chronotherapy.

Elevated asleep blood pressure and non-dipper 24h patterning best predict risk for heart failure that can be averted by bedtime hypertension chronotherapy: A review of the published literature

Several prospective studies consistently report elevated asleep blood pressure (BP) and blunted sleep-time relative systolic BP (SBP) decline (non-dipping) are jointly the most significant prognostic markers of cardiovascular disease (CVD) risk, including heart failure (HF); therefore, they, rather than office BP measurements (OBPM) and ambulatory awake and 24 h BP means, seemingly are the most worthy therapeutic targets for prevention. Published studies of the 24 h BP pattern in HF are sparse in number and of limited sample size. They report high prevalence of the abnormal non-dipper/riser 24 h SBP patterning. Despite the established clinical relevance of the asleep BP, past as do present hypertension guidelines recommend the diagnosis of hypertension rely on OBPM and, when around-the-clock ambulatory BP monitoring (ABPM) is conducted to confirm the elevated OBPM, either on the derived 24 h or "daytime" BP means. Additionally, hypertension guidelines do not advise the time-of-day when BP-lowering medications should be ingested, in spite of known ingestion-time differences in their pharmacokinetics and pharmacodynamics. Between 1976 and 2020, 155 unique trials of ingestion-time differences in the effects of 37 different single and 14 dual-combination hypertension medications, collectively involving 23,972 patients, were published. The vast majority (83.9%) of them found the at-bedtime/evening in comparison to upon-waking/morning treatment schedule resulted in more greatly enhanced: (i) reduction of asleep BP mean without induced sleep-time hypotension; (ii) reduction of the prevalence of the higher CVD risk non-dipper/riser 24 h BP phenotypes; (iii) improvement of kidney function, reduction of cardiac pathology, and with lower incidence of adverse effects. Most notably, no single published randomized trial found significantly better BP-lowering, particularly during sleep, or medical benefits of the most popular upon-waking/morning hypertension treatment-time scheme. Additionally, prospective outcome trials have substantiated that the bedtime relative to the upon-waking, ingestion of BP-lowering medications not only significantly reduces risk of HF but also improves overall CVD event-free survival time.

Systematic review and quality evaluation of published human ingestion-time trials of blood pressure-lowering medications and their combinations

The pharmacokinetics (PK) - absorption, distribution, metabolism, and elimination - and pharmacodynamics (PD) of hypertension medications can be significantly affected by circadian rhythms. As a consequence, the time when blood pressure (BP) lowering medications are ingested, with reference to the staging of all involved circadian rhythms modulating PK and PD, can affect their duration of action, magnitude of effect on features of the 24 h BP profile, and safety. We conducted a systematic and comprehensive review of published prospective human trials that investigated individual hypertension medications of all classes and their combinations for ingestion-time differences in BP-lowering, safety, patient adherence, and markers of hypertension-associated target organ pathology of the kidney and heart. The systematic review yielded 155 trials published between 1976 and 2020 - totaling 23,972 hypertensive individuals - that evaluated 37 different single and 14 dual-combination therapies. The vast (83.9%) majority of them reported clinically and statistically significant benefits - including enhanced reduction of asleep BP mean without induced sleep-time hypotension, reduced prevalence of the higher cardiovascular risk non-dipper 24 h BP profile, decreased incidence of adverse effects, improved kidney function, and reduced cardiac pathology - when hypertension medications are ingested at-bedtime/evening rather than upon-waking/morning. Nonetheless, the findings and conclusions of some past conducted trials are inconsistent, often due to disparities and deficiencies of the investigative protocols. Accordingly, we developed a quality assessment method based upon the eight items identified as crucial according to the recently published guidelines of the International Society for Chronobiology and the American Association for Medical Chronobiology and Chronotherapeutics for the design and conduct of human clinical trials on ingestion-time differences of hypertension medications. Among the most frequent deficiencies are: absence or miscalculation of minimum required sample size (83.2%), incorrect choice of primary BP endpoint (53.6%), and inappropriate arbitrary and unrepresentative clock hours chosen for tested treatment times (53.6%). The inability of the very small proportion (16.1%) of trials to verify the advantages of the at-bedtime/evening treatment strategy is likely explained by deficiencies of their study design and conduct. Nonetheless, regardless of the quality score of the 155 trials retrieved by our systematic review, it is most noteworthy that no single published prospective randomized trial reported significantly enhanced BP-lowering, safety, compliance, or other benefits of the unjustified by medical evidence, yet still most recommended, upon-waking/morning hypertension treatment-time scheme.

The circadian clock and metabolic homeostasis: entangled networks

The circadian clock exerts an important role in systemic homeostasis as it acts a keeper of time for the organism. The synchrony between the daily challenges imposed by the environment needs to be aligned with biological processes and with the internal circadian clock. In this review, it is provided an in-depth view of the molecular functioning of the circadian molecular clock, how this system is organized, and how central and peripheral clocks communicate with each other. In this sense, we provide an overview of the neuro-hormonal factors controlled by the central clock and how they affect peripheral tissues. We also evaluate signals released by peripheral organs and their effects in the central clock and other brain areas. Additionally, we evaluate a possible communication between peripheral tissues as a novel layer of circadian organization by reviewing recent studies in the literature. In the last section, we analyze how the circadian clock can modulate intracellular and tissue-dependent processes of metabolic organs. Taken altogether, the goal of this review is to provide a systemic and integrative view of the molecular clock function and organization with an emphasis in metabolic tissues.

Daily rhythms of both host and parasite affect antimalarial drug efficacy

BACKGROUND AND OBJECTIVES

Circadian rhythms contribute to treatment efficacy in several non-communicable diseases. However, chronotherapy (administering drugs at a particular time-of-day) against infectious diseases has been overlooked. Yet, the daily rhythms of both hosts and disease-causing agents can impact the efficacy of drug treatment. We use the rodent malaria parasite Plasmodium chabaudi, to test whether the daily rhythms of hosts, parasites and their interactions affect sensitivity to the key antimalarial, artemisinin.

METHODOLOGY

Asexual malaria parasites develop rhythmically in the host's blood, in a manner timed to coordinate with host daily rhythms. Our experiments coupled or decoupled the timing of parasite and host rhythms, and we administered artemisinin at different times of day to coincide with when parasites were either at an early (ring) or later (trophozoite) developmental stage. We quantified the impacts of parasite developmental stage, and alignment of parasite and host rhythms, on drug sensitivity.

RESULTS

We find that rings were less sensitive to artemisinin than trophozoites, and this difference was exacerbated when parasite and host rhythms were misaligned, with little direct contribution of host time-of-day on its own. Furthermore, the blood concentration of haem at the point of treatment correlated positively with artemisinin efficacy but only when parasite and host rhythms were aligned.

CONCLUSIONS AND IMPLICATIONS

Parasite rhythms influence drug sensitivity in vivo. The hitherto unknown modulation by alignment between parasite and host daily rhythms suggests that disrupting the timing of parasite development could be a novel chronotherapeutic approach.

LAY SUMMARY

We reveal that chronotherapy (providing medicines at a particular time-of-day) could improve treatment for malaria infections. Specifically, parasites' developmental stage at the time of treatment and the coordination of timing between parasite and host both affect how well antimalarial drug treatment works.

Translating around the clock: Multi-level regulation of post-transcriptional processes by the circadian clock

The endogenous circadian clock functions to maintain optimal physiological health through the tissue specific coordination of gene expression and synchronization between tissues of metabolic processes throughout the 24 hour day. Individuals face numerous challenges to circadian function on a daily basis resulting in significant incidences of circadian disorders in the United States and worldwide. Dysfunction of the circadian clock has been implicated in numerous diseases including cancer, diabetes, obesity, cardiovascular and hepatic abnormalities, mood disorders and neurodegenerative diseases. The circadian clock regulates molecular, metabolic and physiological processes through rhythmic gene expression via transcriptional and post-transcriptional processes. Mounting evidence indicates that post-transcriptional regulation by the circadian clock plays a crucial role in maintaining tissue specific biological rhythms. Circadian regulation affecting RNA stability and localization through RNA processing, mRNA degradation, and RNA availability for translation can result in rhythmic protein synthesis, even when the mRNA transcripts themselves do not exhibit rhythms in abundance. The circadian clock also targets the initiation and elongation steps of translation through multiple pathways. In this review, the influence of the circadian clock across the levels of post-transcriptional, translation, and post-translational modifications are examined using examples from humans to cyanobacteria demonstrating the phylogenetic conservation of circadian regulation. Lastly, we briefly discuss chronotherapies and pharmacological treatments that target circadian function. Understanding the complexity and levels through which the circadian clock regulates molecular and physiological processes is important for future advancement of therapeutic outcomes.

Circadian rhythms: influence on physiology, pharmacology, and therapeutic interventions

Circadian rhythms are ubiquitous phenomena that recur daily in a self-sustaining, entrainable, and oscillatory manner, and orchestrate a wide range of molecular, physiological, and behavioral processes. Circadian clocks are comprised of a hierarchical network of central and peripheral clocks that generate, sustain, and synchronize the circadian rhythms. The functioning of the peripheral clock is regulated by signals from autonomic innervation (from the central clock), endocrine networks, feeding, and other external cues. The critical role played by circadian rhythms in maintaining both systemic and tissue-level homeostasis is well established, and disruption of the rhythm has direct consequence for human health, disorders, and diseases. Circadian oscillations in both pharmacokinetics and pharmacodynamic processes are known to affect efficacy and toxicity of several therapeutic agents. A variety of modeling approaches ranging from empirical to more complex systems modeling approaches have been applied to characterize circadian biology and its influence on drug actions, optimize time of dosing, and identify opportunities for pharmacological modulation of the clock mechanisms and their downstream effects. In this review, we summarize current understanding of circadian rhythms and its influence on physiology, pharmacology, and therapeutic interventions, and discuss the role of chronopharmacometrics in gaining new insights into circadian rhythms and its applications in chronopharmacology.

Circadian Effects of Drug Responses

Circadian rhythms describe physiological systems that repeat themselves with a cycle of approximately 24 h. Our understanding of the cellular and molecular origins of these oscillations has improved dramatically, allowing us to appreciate the significant role these oscillations play in maintaining physiological homeostasis. Circadian rhythms allow living organisms to predict and efficiently respond to a dynamically changing environment, set by repetitive day/night cycles. Since circadian rhythms underlie almost every aspect of human physiology, it is unsurprising that they also influence the response of a living organism to disease, stress, and therapeutics. Therefore, not only do the mechanisms that maintain health and disrupt homeostasis depend on our internal circadian clock, but also the way drugs are perceived and function depends on these physiological rhythms. We present a holistic view of the therapeutic process, discussing components such as disease state, pharmacokinetics, and pharmacodynamics, as well as adverse reactions that are critically affected by circadian rhythms. We outline challenges and opportunities in moving toward personalized medicine approaches that explore and capitalize on circadian rhythms for the benefit of the patient.

Ingestion-time differences in the pharmacodynamics of hypertension medications: Systematic review of human chronopharmacology trials

Pharmacokinetics of hypertension medications is significantly affected by circadian rhythms that influence absorption, distribution, metabolism and elimination. Furthermore, their pharmacodynamics is affected by ingestion-time differences in kinetics and circadian rhythms comprising the biological mechanism of the 24 h blood pressure (BP) pattern. However, hypertension guidelines do not recommend the time to treat patients with medications. We conducted a systematic review of published evidence regarding ingestion-time differences of hypertension medications and their combinations on ambulatory BP-lowering, safety, and markers of target organ pathology. Some 153 trials published between 1976 and 2020, totaling 23,869 hypertensive individuals, evaluated 37 different single and 14 dual-fixed combination therapies. The vast (83.7%) majority of the trials report clinically and statistically significant benefits - including enhanced reduction of asleep BP without inducing sleep-time hypotension, reduced prevalence of the higher cardiovascular disease risk BP non-dipping 24 h profile, decreased incidence of adverse effects, improved renal function, and reduced cardiac pathology - when hypertension medications are ingested at-bedtime/evening rather than upon-waking/morning. Non-substantiated treatment-time difference in effects by the small proportion (16.3%) of published trials is likely explained by deficiencies of study design and conduct. Systematic and comprehensive review of the literature published the past 45 years reveals no single study reported significantly better benefit of the still conventional, yet unjustified by medical evidence, upon-waking/morning hypertension treatment schedule.

Extent of asleep blood pressure reduction by hypertension medications is ingestion-time dependent: Systematic review and meta-analysis of published human trials

Combined evidence of published prospective outcome trials and meta-analyses substantiate elevated asleep blood pressure (BP) and blunted sleep-time relative BP decline (non-dipping), regardless of wake-time office BP and awake or 24 h BP means, are jointly the most highly significant independent prognostic markers of cardiovascular disease (CVD) risk and worthy therapeutic targets for prevention. Nonetheless, current guidelines continue to recommend the diagnosis of hypertension, when based on ambulatory BP monitoring (ABPM), rely, solely, on either the 24 h or "daytime" BP means. They also fail to recommend the time to treat patients. We conducted a systematic review of published human trials regarding ingestion-time differences in the effects of hypertension medications on asleep BP and sleep-time relative BP decline. Some 62 such trials published between 1992 and 2020, totaling 6120 hypertensive persons, evaluated 21 different single and 8 dual-fixed combination therapies. The vast (82.3%) majority of the trials substantiate the bedtime/evening vs. upon-waking/morning treatment schedule produces statistically significant better clinical benefits, including enhanced reduction of asleep systolic BP by an average 5.17 mmHg (95%CI [4.04, 6.31], P < 0.001 between treatment-time groups) without inducing sleep-time hypotension, reduced prevalence of the high CVD risk non-dipper 24 h BP pattern, improved kidney function, and reduced cardiac pathology. Furthermore, systematic and comprehensive review of the ABPM-based literature published the past 29 years reveals no single study that reported significantly better benefits of the most recommended, yet unjustified by medical evidence, morning hypertension treatment-time scheme.

Are patients with cognitive impairment fit to fly? Current evidence and practical recommendations

BACKGROUND

The worldwide prevalence of dementia is increasing and represents a major public health concern. In the last decades, air travel services have undergone an impressive expansion and one of ten passengers is aged 65 years and older. While air travel can be stressful at all ages and health conditions, older individuals with cognitive impairment carry a greater risk for air-travel-related complications. Consequently, demands to general practitioners for assessing their older patient's fitness to fly are increasing.

METHODS

We conducted a search of the literature in PubMed on the impact of in-flight environmental changes on passengers with cognitive impairment and possible resulting complications. This set the base for a discussion on pharmacological and non-pharmacological interventions aimed at preventing in-flight complications in this vulnerable population.

RESULTS

While our research strategy identified a total of 11 articles related to older age and air travel, only three focused on passengers with cognitive impairment. Our literature review showed that the airplane environment may lead to a large spectrum of symptoms in passengers of all age groups. However, passengers with cognitive impairment due to neurodegenerative diseases are at increased risk for experiencing the most extreme symptoms such as acute confusional state. Non-pharmacological and pharmacological interventions at different stages of the travel process (before, during and after) can help prevent complications in this vulnerable population.

CONCLUSION

The decision to let a patient with cognitive impairment fly requires a solid understanding of the in-flight environmental changes and their impact on older patients with cognitive impairment. Moreover, a sound weighing of the risks and benefits while considering different aspects of the patient's history is demanded. In this regard, the role of the treating physicians and caregivers is essential along with the support of the medical department of the airline.

Circadian regulation of transporter expression and implications for drug disposition

Introduction: Solute Carrier (SLC) and ATP-binding cassette (ABC) transporters expressed in the intestine, liver, and kidney determine the absorption, distribution, and excretion of drugs. In addition, most molecular and cellular processes show circadian rhythmicity controlled by circadian clocks that leads to diurnal variations in the pharmacokinetics and pharmacodynamics of many drugs and affects their therapeutic efficacy and toxicity.Area covered: This review provides an overview of the current knowledge on the circadian rhythmicity of drug transporters and the molecular mechanisms of their circadian control. Evidence for coupling drug transporters to circadian oscillators and the plausible candidates conveying circadian clock signals to target drug transporters, particularly transcription factors operating as the output of clock genes, is discussed.Expert opinion: The circadian machinery has been demonstrated to interact with the uptake and efflux of various drug transporters. The evidence supports the concept that diurnal changes that affect drug transporters may influence the pharmacokinetics of the drugs. However, more systematic studies are required to better define the timing of pharmacologically important drug transporter regulation and determine tissue- and sex-dependent differences. Finally, the transfer of knowledge based on the results and conclusions obtained primarily from animal models will require careful validation before it is applied to humans.

Guidelines for the design and conduct of human clinical trials on ingestion-time differences - chronopharmacology and chronotherapy - of hypertension medications

Current hypertension guidelines fail to provide a recommendation on when-to-treat, thus disregarding relevant circadian rhythms that regulate blood pressure (BP) level and 24 h patterning and medication pharmacokinetics and pharmacodynamics. The ideal purpose of ingestion-time (chronopharmacology, i.e. biological rhythm-dependent effects on the kinetics and dynamics of medications, and chronotherapy, i.e. the timing of pharmaceutical and other treatments to optimize efficacy and safety) trials should be to explore the potential impact of endogenous circadian rhythms on the effects of medications. Such investigations and outcome trials mandate adherence to the basic standards of human chronobiology research. In-depth review of the more than 150 human hypertension pharmacology and therapeutic trials published since 1974 that address the differential impact of upon-waking/morning versus at-bedtime/evening schedule of treatment reveals diverse protocols of sometimes suboptimal or defective design and conduct. Many have been "time-of-day," i.e. morning versus evening, rather than circadian-time-based, and some relied on wake-time office BP rather than around-the-clock ambulatory BP measurements (ABPM). Additionally, most past studies have been of too small sample size and thus statistically underpowered. As of yet, there has been no consensual agreement on the proper design, methods and conduct of such trials. This Position Statement recommends ingestion-time hypertension trials to follow minimum guidelines: (i) Recruitment of participants should be restricted to hypertensive individuals diagnosed according to ABPM diagnostic thresholds and of a comparable activity/sleep routine. (ii) Tested treatment-times should be selected according to internal biological time, expressed by the awakening and bed times of the sleep/wake cycle. (iii) ABPM should be the primary or sole method of BP assessment. (iv) The minimum-required features for analysis of the ABPM-determined 24 h BP pattern ought to be the asleep (not "nighttime") BP mean and sleep-time relative BP decline, calculated in reference to the activity/rest cycle per individual. (v) ABPM-obtained BP means should be derived by the so-called adjusted calculation procedure, not by inaccurate arithmetic averages. (vi) ABPM should be performed with validated and calibrated devices at least hourly throughout two or more consecutive 24 h periods (48 h in total) to achieve the highest reproducibility of mean wake-time, sleep-time and 48 h BP values plus the reliable classification of dipping status. (vii) Calculation of minimum required sample size in adherence with proper statistical methods must be provided. (viii) Hypertension chronopharmacology and chronotherapy trials should preferably be randomized double-blind, randomized open-label with blinded-endpoint, or crossover in design, the latter with sufficient washout period between tested treatment-time regimens.

The impact of acetylsalicylic acid dosed at bedtime on circadian rhythms of blood pressure in the high-risk group of cardiovascular patients-a randomized, controlled trial

Purpose

Time of drug administration may significantly influence its effect. The aim of the present study was to investigate the effect of ASA (administrated in the morning or in the evening) on the anti-hypertensive effect and diurnal blood pressure profile in the high-risk group of cardiovascular patients.

Methods

All patients (n = 114) had been diagnosed with coronary heart disease and arterial hypertension prior to the enrolment and had been treated with 75 mg per day of ASA in the morning. The patients were randomly assigned to one of the two study groups receiving 75 mg of ASA per day in a single antiplatelet therapy for 3 months in the morning (n = 58) or in the evening (n = 56). The control group (n = 61) consisted of patients with arterial hypertension but without coronary heart disease, not receiving ASA. In all the patients, during each visit, clinical blood pressure (BP) and ambulatory blood pressure measurements (ABPM) were performed.

Results

There was a significant reduction in 24-h BP and blood pressure at night in the ASA group evening group compared with the ASA morning group and the control group.

Conclusions

The present study demonstrated that compared with the use of ASA in the morning, its administration in the evening may lead to favourable drop in the ABPM and an improvement of the diurnal profile in the high-risk group of cardiovascular patients who are not naïve to ASA.

Electronic supplementary material

The online version of this article (10.1007/s00228-020-02997-8) contains supplementary material, which is available to authorized users.

Circadian Clock-Controlled Drug Metabolism: Implications for Chronotherapeutics

Dependence of drug metabolism on dosing time has long been recognized. However, only recently are the underlying mechanisms for circadian drug metabolism being clarified. Diurnal rhythmicity in expression of drug-metabolizing enzymes is believed to be a key factor determining circadian metabolism. Supporting the notion that biological rhythms are generated and maintained by the circadian clock, a number of diurnal enzymes are under the control of the circadian clock. In general, circadian clock genes generate and regulate diurnal rhythmicity in drug-metabolizing enzymes via transcriptional actions on one or two of three cis-elements (i.e., E-box, D-box, and Rev-erb response element or RAR-related orphan receptor response element). Additionally, cycling or clock-controlled nuclear receptors such as hepatocyte nuclear factor 4α and peroxisome proliferator-activated receptor γ are contributors to diurnal enzyme expression. These newly discovered mechanisms for each of the rhythmic enzymes are reviewed in this article. We also discuss how the rhythms of enzymes are translated to circadian pharmacokinetics and drug chronotoxicity, which has direct implications for chronotherapeutics. Our discussion is also extended to two diurnal transporters (P-glycoprotein and multidrug resistance-associated protein 2) that have an important role in drug absorption. Although the experimental evidence is lacking in metabolism-based chronoefficacy, circadian genes (e.g., Rev-erbα) as drug targets are shown to account for diurnal variability in drug efficacy. SIGNIFICANCE STATEMENT: Significant progress has been made in understanding the molecular mechanisms for generation of diurnal rhythmicity in drug-metabolizing enzymes. In this article, we review the newly discovered mechanisms for each of the rhythmic enzymes and discuss how the rhythms of enzymes are translated to circadian pharmacokinetics and drug chronotoxicity, which has direct implications for chronotherapeutics.

The Circadian Clock, the Immune System, and Viral Infections: The Intricate Relationship Between Biological Time and Host-Virus Interaction

Living beings spend their lives and carry out their daily activities interacting with environmental situations that present space-time variations and that involve contact with other life forms, which may behave as commensals or as invaders and/or parasites. The characteristics of the environment, as well as the processes that support the maintenance of life and that characterize the execution of activities of daily life generally present periodic variations, which are mostly synchronized with the light–dark cycle determined by Earth’s rotation on its axis. These rhythms with 24-h periodicity, defined as circadian, influence events linked to the interaction between hosts and hosted microorganisms and can dramatically determine the outcome of this interplay. As for the various pathological conditions resulting from host–microorganism interactions, a particularly interesting scenario concerns infections by viruses. When a viral agent enters the body, it alters the biological processes of the infected cells in order to favour its replication and to spread to various tissues. Though our knowledge concerning the mutual influence between the biological clock and viruses is still limited, recent studies start to unravel interesting aspects of the clock–virus molecular interplay. Three different aspects of this interplay are addressed in this mini-review and include the circadian regulation of both innate and adaptive immune systems, the impact of the biological clock on viral infection itself, and finally the putative perturbations that the virus may confer to the clock leading to its deregulation.

Chronopharmacology of glucocorticoids

Glucocorticoids influence a wide array of metabolic, anti-inflammatory, immunosuppressive, and cognitive signaling processes, playing an important role in homeostasis and preservation of normal organ function. Synthesis is regulated by the hypothalamic-pituitary-adrenal (HPA) axis of which cortisol is the primary glucocorticoid in humans. Synthetic glucocorticoids are important pharmacological agents that augment the anti-inflammatory and immunosuppressive properties of endogenous cortisol and are widely used for the treatment of asthma, Crohn's disease, and rheumatoid arthritis, amongst other chronic conditions. The homeostatic activity of cortisol is disrupted by the administration of synthetic glucocorticoids and so there is interest in developing treatment options that minimize HPA axis disturbance while maintaining the pharmacological effects. Studies suggest that optimizing drug administration time can achieve this goal. The present review provides an overview of endogenous glucocorticoid activity and recent advances in treatment options that have further improved patient safety and efficacy with an emphasis on chronopharmacology.

Chronotherapeutics: Recognizing the Importance of Timing Factors in the Treatment of Disease and Sleep Disorders

This review describes the characteristics of a number of pathologies, which are considered from the point of view of chronobiology, that is, the way in which biological processes are expressed throughout the 24-hour day. This perspective is a relatively new way of thinking about disease and additionally about how to treat diseases. It has called attention to the importance of not only the quantity of a drug that is administered but also when it is administered. In addition, the review presents an overview of the emerging clinical strategies known as chronotherapeutics, that is, the effects of the daily scheduling of drug administration and the consequences of the activity and efficacy of therapies that are applied in this manner. This article also reviews innovative ways in which physicians are applying time-specified drug treatment (chronopharmacology) for sleep disorders. Here, we present a systematic description of chronopharmacology as well as definitions of key terms that, we believe, will be helpful for newcomers to the field. It is hoped that greater awareness of this new perspective on pharmacology will promote its adoption by researchers and clinicians.

The importance of determining circadian parameters in pharmacological studies

In mammals, most molecular and cellular processes show circadian changes, leading to daily variations in physiology and ultimately in behaviour. Such daily variations induce a temporal coordination of processes that is essential to ensure homeostasis and health. Thus, it is of no surprise that pharmacokinetics (PK) and pharmacodynamics (PD) of many drugs are also subject to circadian variations, profoundly affecting their efficacy and tolerability. Understanding how circadian rhythms influence drug PK, PD, and toxicity might significantly improve treatment efficacy and decrease related side effects. Therefore, it is essential to take circadian variations into account and to determine circadian parameters in pharmacological studies, especially when drugs have a short half-life or target rhythmic processes. This review provides an overview of the current knowledge on circadian rhythms and their relevance to the field of pharmacology. Methodologies to evaluate circadian rhythms in vitro, in rodent models and in humans, from experimental to computational approaches, are described and discussed. Lastly, we aim at alerting the scientific, medical, and regulatory communities to the relevance of the physiological time, as a key parameter to be considered when designing pharmacological studies. This will eventually lead to more successful preclinical and clinical trials and pave the way to a more personalized treatment to the benefit of the patients.