Time-Dependent Effects of Low-Dose Aspirin on Plasma Renin Activity, Aldosterone, Cortisol, and Catecholamines

Effect of aspirin on blood pressure in hypertensive patients: a systematic review and meta-analysis

INTRODUCTION

Aspirin is widely used for secondary prevention in patients with hypertension. However, previous studies mainly focused on the preventive effects of aspirin, and there has been a lack of reliable evidence on whether taking aspirin affects blood pressure This study aimed to investigate whether aspirin would affect the blood pressure in patients with hypertension.

METHODS

PubMed, Cochrane database, Embase, Scopus and Medline databases were searched until September 2023. For continuous variables (e.g., blood pressure reduction), the mean difference (MD) was selected as the effect magnitude indices. We used the Cochrane Collaboration's Risk of Bias tool to assess the risk of bias.

RESULT

A total of five studies were included, comprising 20,312 patients. We found that aspirin did not affect SBP (MD = -0.78, 95% CI: - 2.41, 0.84). A similar result was found for DBP (MD = -0.86, 95% CI: - 2.14, 0.42).

CONCLUSION

This study showed no significant difference in blood pressure between the aspirin and control groups, suggesting that aspirin does not affect blood pressure.

Aspirin in Pregnancy

Preeclampsia is associated with significant perinatal morbidity and mortality. Aspirin has been long purported and extensively studied for prevention of preeclampsia. For this reason, the U.S. Preventive Services Task Force, the American College of Obstetricians and Gynecologists, and the Society for Maternal-Fetal Medicine recommend its use in pregnancy for preeclampsia prevention in those at high risk. Yet, much controversy exists regarding optimal use in pregnancy with guidelines across global organizations varying. In this narrative review, we summarize the published literature related to the safety, optimal dose, and timing and duration of use of aspirin, as well as other indications for which aspirin has been studied in pregnancy.

Circadian Factors in Stroke: A Clinician's Perspective

Stroke remains one of the leading causes of mortality and long-term and permanent disability worldwide despite technological innovations and developments in pharmacotherapy. In the last few decades, the growing data have evidenced the role of the circadian system in brain vulnerability to damage, the development and evolution of stroke, and short-term and long-term recovery. On the other hand, the stroke itself can affect the circadian system via direct injury of specific brain structures involved in circadian regulation (i.e., hypothalamus, retinohypothalamic tracts, etc.) and impairment of endogenous regulatory mechanisms, metabolic derangement, and a neurogenic inflammatory response in acute stroke. Moreover, the disruption of circadian rhythms can occur or exacerbate as a result of exogenous factors related to hospitalization itself, the conditions in the intensive care unit and the ward (light, noise, etc.), medication (sedatives and hypnotics), and loss of external factors entraining the circadian rhythms. In the acute phase of stroke, patients demonstrate abnormal circadian variations in circadian biomarkers (melatonin, cortisol), core body temperature, and rest-activity patterns. The approaches aimed at the restoration of disrupted circadian patterns include pharmacological (melatonin supplementation) and non-medication (bright light therapy, shifting feeding schedules, etc.) interventions; however, their effects on short- and long-term recovery after stroke are not well understood.

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.

Implications of Circadian Rhythm in Stroke Occurrence: Certainties and Possibilities

Stroke occurrence is not randomly distributed over time but has circadian rhythmicity with the highest frequency of onset in the morning hours. This specific temporal pattern is valid for all subtypes of cerebral infarction and intracerebral hemorrhage. It also correlates with the circadian variation of some exogenous factors such as orthostatic changes, physical activity, sleep-awake cycle, as well as with endogenous factors including dipping patterns of blood pressure, or morning prothrombotic and hypofibrinolytic states with underlying cyclic changes in the autonomous system and humoral activity. Since the internal clock is responsible for these circadian biological changes, its disruption may increase the risk of stroke occurrence and influence neuronal susceptibility to injury and neurorehabilitation. This review aims to summarize the literature data on the circadian variation of cerebrovascular events according to physiological, cellular, and molecular circadian changes, to survey the available information on the chronotherapy and chronoprophylaxis of stroke and its risk factors, as well as to discuss the less reviewed impact of the circadian rhythm in stroke onset on patient outcome and functional status after stroke.

A Systematic Review of the Efficacy and Safety of Aspirin When Delivered at Different Medication Times for the Primary and Secondary Prevention of Cardiovascular and Cerebrovascular Diseases

PURPOSE

Effective antiplatelet therapy can significantly reduce the incidence and mortality rate of cardiovascular and cerebrovascular diseases. Aspirin is widely used in the secondary prevention of cardiovascular and cerebrovascular diseases; however, there is widespread debate as to when patients should take an enteric-coated aspirin tablet on a daily basis. In the present study, we evaluated the efficacy and safety of different aspirin medication times (morning or before bedtime) in terms of the primary and secondary prevention of cardiovascular and cerebrovascular diseases using meta-analysis.

METHODS

Studies with randomized control trials (RCT) or crossover trials regarding to the usage of aspirin (morning or before bedtime) for the primary or secondary prevention of cardiovascular and cerebrovascular diseases were searched in Medline, EMbase, Cochrane Library, CNKI, Wanfang Data, VIP Database and CBM. Review Manager 5 (RevMan 5, v5.3), a Cochrane systematic reviews software, was used to perform meta-analysis based on the recommendation of the Cochrane Handbook for risk assessment tools.

RESULTS

Meta-analysis showed that taking low-dose aspirin tablets before bed reduced systolic and diastolic blood pressure compared with taking it in the morning. At the same time, the number of studies on platelet aggregation rate, C-reactive protein (CRP), serum nitric oxide (NO) or thromboxane B₂ (TXB₂) is too small to be reliable. However, there was a large heterogeneity across the studies. The quality of some studies was not high enough.

CONCLUSION

Additional blood pressure benefits can be achieved by taking aspirin before bedtime, but it does not affect its antiplatelet effect and does not pose a higher risk of bleeding.

Therapeutics on the clock: Circadian medicine in the treatment of chronic inflammatory diseases

The circadian clock is a collection of endogenous oscillators with a periodicity of ~ 24 h. Recently, our understanding of circadian rhythms and their regulation at genomic and physiologic scales has grown significantly. Knowledge of the circadian influence on biological processes has provided new possibilities for novel pharmacological strategies. Directly targeting the biological clock or its downstream targets, and/or using timing as a variable in drug therapy are now important pharmacological considerations. The circadian machinery mediates many aspects of the inflammatory response and, reciprocally, an inflammatory environment can disrupt circadian rhythms. Therefore, intense interest exists in leveraging circadian biology as a means to treat chronic inflammatory diseases such as sepsis, asthma, rheumatoid arthritis, osteoarthritis, and cardiovascular disease, which all display some type of circadian signature. The purpose of this review is to evaluate the crosstalk between circadian rhythms, inflammatory diseases, and their pharmacological treatment. Evidence suggests that carefully rationalized application of chronotherapy strategies - alone or in combination with small molecule modulators of circadian clock components - can improve efficacy and reduce toxicity, thus warranting further investigation and use.

A novel time-dimension and circadian rhythm-dependent strategy for pharmacodynamic evaluation of Uncaria in the regulation of neurotransmitter circadian metabolic homeostasis in spontaneously hypertensive rats

In the present study, we aimed to use metabolomics platforms to examine circadian-regulated neurotransmitters across a 24-h day and the effects of Uncaria administration on daily rhythmicity in order to establish a strategy for evaluating the spatiotemporal efficacy evaluation strategy of Uncaria. By using targeted ultrahigh performance liquid chromatography-mass spectrometry metabolomics, we quantified 32 neurotransmitter metabolites every 4 h over 24 h. To assess 24-h metabolite rhythmicity, we performed cosinor analysis. The expression of hypothalamic rhythm genes was detected by reverse transcription polymerase chain reaction (RT-PCR). Data revealed circadian loss of many neurotransmitters during the entire circadian cycle in the serum of group M, indicating that hypertension causes circadian rhythm disorders. Cosinor analysis of the rhythmic oscillations of the levels of 32 neurotransmitters in the three groups showed that the metabolite rhythms peaked at approximately the same time of day (ZT4 and ZT16). Moreover, the amplitudes of the metabolite rhythms were altered. After treatment with Uncaria, the amplitudes of 13 neurotransmitters reverted to normal. The change trends in the hypothalamic rhythm genes confirmed the rhythm changes in neurotransmitters. Collectively, a novel pharmacodynamic evaluation strategy was established to dynamically observe the holistic effects of Uncaria on 32 circulating neurotransmitters within 24 h from the perspective of time dimension.

Targeted neurotransmitter metabolomics profiling of oleanolic acid in the treatment of spontaneously hypertensive rats

Essential hypertension (EH) is a prevalent chronic medical condition and a major risk factor for cardiovascular morbidity and mortality. Neurotransmitters are involved in the physiological process of blood pressure regulation in the body. Studies have shown that oleanolic acid (OA) can effectively regulate neurotransmitter-related metabolic disorders caused by EH, but the mechanism is still unclear. Here, we studied the neurotransmitter metabolic profiles in five brain regions by targeted metabolomics approaches in spontaneously hypertensive rats (SHRs) treated with OA and vehicle. Samples from five brain regions (hippocampus, striatum, hypothalamus, temporal lobe, and frontal lobe) were collected from the control group, the spontaneously hypertensive rat (SHR) group, and the OA group. Targeted metabolomics based on UPLC-Q-Exactive-MS was employed to characterize the dramatically changed neurotransmitters in the brain regions of SHRs treated with OA and vehicle. The expressions of the key enzymes involved in the neurotransmitter metabolism were detected by the reverse transcription-polymerase chain reaction (RT-PCR). The metabolomic profiles of SHRs pre-protected by OA were significantly different from those of unprotected SHRs. A total of 18 neurotransmitters could be confirmed as significantly altered metabolites, which were involved in tyrosine and glutamate metabolism as well as other pathways. The results showing seven key enzymes in neurotransmitter metabolism further validated the changes in the metabolic pathways. OA could effectively restore tyrosine metabolism in the striatum and hypothalamus, glutamate metabolism in the hippocampus, striatum and temporal lobe, cholinergic metabolism in the striatum, and histidine metabolism in the hypothalamus due to its inhibition of inflammatory reactions, structural damage of the neuronal cells, and increase in sedative activity. This study indicated that brain region-targeted metabolomics can provide a powerful tool to further investigate the possible mechanism of OA in EH.

Evaluation of the antihypertensive effect of nocturnal administration of acetylsalicylic acid: a cross-over randomized clinical trial

OBJECTIVE

Several studies have shown that evening intake of aspirin has antihypertensive effect in healthy adults, which has not been proven in patients with cardiovascular disease, who mostly take aspirin in the morning. We have evaluated the antihypertensive effect of bedtime administration of aspirin in patients with cardiovascular disease already treated for hypertension.

METHODS

This is a multicenter randomized triple-blind placebo-controlled crossover trial, with hypertensive patients treated with aspirin for secondary prevention. There was a baseline-randomized assignment to 2-month periods of bedtime aspirin (100 mg) first and morning-time aspirin later, or inversely, both periods separated by an open label 2-4 weeks period of morning-time aspirin. At the start and end of each treatment period, a 24-h ambulatory blood pressure monitoring was performed. The main outcome measure was mean 24-h blood pressure. The analyses were performed according to the intention-to-treat principle.

RESULTS

Overall, 225 patients were randomized. No significant differences were observed in ambulatory blood pressure by time of intake of usual low doses of aspirin. The mean SBP/DBP was 123.2/69.9 (95% CI 121.58-124.9/68.86-76.86) with bedtime administration and 122.4/68.8 (95% CI 120.76-124.01/67.85-69.83) with daytime administration (P = 0.3 and P = 0.23 for SBP and DBP, respectively).

CONCLUSION

Administering aspirin at bedtime rather than in the morning does not modify the 24-h ambulatory blood pressure in hypertensive patients in secondary cardiovascular prevention.The trial was registered with ClinicalTrials.gov (number NCT01741922).

The role of aspirin, heparin, and other interventions in the prevention and treatment of fetal growth restriction

Fetal growth restriction and related placental pathologies such as preeclampsia, stillbirth, and placental abruption are believed to arise in early pregnancy when inadequate remodeling of the maternal spiral arteries leads to persistent high-resistance and low-flow uteroplacental circulation. The consequent placental ischaemia, reperfusion injury, and oxidative stress are associated with an imbalance in angiogenic/antiangiogenic factors. Many interventions have centered on the prevention and/or treatment of preeclampsia with results pertaining to fetal growth restriction and small-for-gestational-age pregnancy often included as secondary outcomes because of the common pathophysiology. This renders the study findings less reliable for determining clinical significance. For the prevention of fetal growth restriction, a recent large-study level meta-analysis and individual patient data meta-analysis confirm that aspirin modestly reduces small-for-gestational-age pregnancy in women at high risk (relative risk, 0.90, 95% confidence interval, 0.81-1.00) and that a dose of ≥100 mg should be recommended and to start at or before 16 weeks of gestation. These findings support national clinical practice guidelines. In vitro and in vivo studies suggest that low-molecular-weight heparin may prevent fetal growth restriction; however, evidence from randomized control trials is inconsistent. A meta-analysis of multicenter trial data does not demonstrate any positive preventative effect of low-molecular-weight heparin on a primary composite outcome of placenta-mediated complications including fetal growth restriction (18% vs 18%; absolute risk difference, 0.6%; 95% confidence interval, 10.4-9.2); use of low-molecular-weight heparin for the prevention of fetal growth restriction should remain in the research setting. There are even fewer treatment options once fetal growth restriction is diagnosed. At present the only management option if the risk of hypoxia, acidosis, and intrauterine death is high is iatrogenic preterm birth, with the use of peripartum maternal administration of magnesium sulphate for neuroprotection and corticosteroids for fetal lung maturity, to prevent adverse neonatal outcomes. The pipeline of potential therapies use different strategies, many aiming to increase fetal growth by improving poor placentation and uterine blood flow. Phosphodiesterase type 5 inhibitors that potentiate nitric oxide availability such as sildenafil citrate have been extensively researched both in preclinical and clinical studies; results from the Sildenafil Therapy In Dismal Prognosis Early-Onset Intrauterine Growth Restriction consortium of randomized control clinical trials are keenly awaited. Targeting the uteroplacental circulation with novel therapeutics is another approach, the most advanced being maternal vascular endothelial growth factor gene therapy, which is being translated into the clinic via the doEs Vascular endothelial growth factor gene therapy safEly impRove outcome in seveRe Early-onset fetal growth reSTriction consortium. Other targeting approaches include nanoparticles and microRNAs to deliver drugs locally to the uterine arterial endothelium or trophoblast. In vitro and in vivo studies and animal models have demonstrated effects of nitric oxide donors, dietary nitrate, hydrogen sulphide donors, statins, and proton pump inhibitors on maternal blood pressure, uteroplacental resistance indices, and angiogenic/antiangiogenic factors. Data from human pregnancies and, in particular, pregnancies with fetal growth restriction remain very limited. Early research into melatonin, creatine, and N-acetyl cysteine supplementation in pregnancy suggests they may have potential as neuro- and cardioprotective agents in fetal growth restriction.

Aspirin and blood pressure: Effects when used alone or in combination with antihypertensive drugs

Arterial hypertension is a major risk factor for cardiovascular and renal events. Lowering blood pressure is thus an important strategy for reducing morbidity and mortality. Since low-dose aspirin is a cornerstone in the prevention of adverse cardiovascular outcomes, combined treatment with aspirin and antihypertensive drugs is very common. However, the impact of aspirin therapy on blood pressure control remains a subject of intense debate. Recent data suggest that the cardioprotective action of aspirin extends beyond its well-known antithrombotic effect. Aspirin has been shown to trigger the synthesis of specialized pro-resolving lipid mediators from arachidonic acid and omega-3 fatty acids. These novel anti-inflammatory and pro-resolving mediators actively stimulate the resolution of inflammation and tissue regeneration. Additionally, they may contribute to other protective effects on redox status and vascular reactivity that have also been attributed to aspirin. Of note, aspirin has been shown to improve vasodilation through cyclooxygenase-independent mechanisms. On the other hand, higher aspirin doses have been reported to exert a negative impact on blood pressure due to inhibition of cyclooxygenase-2 activity, which reduces renal blood flow, glomerular filtration rate and sodium and water excretion. This review aims to provide an overview of the effects of aspirin on blood pressure and the underlying mechanisms, focusing on the interaction between aspirin and antihypertensive drugs. Studies in both experimental and human hypertension are presented.

Time-Dependent Effects of Aspirin on Blood Pressure and Morning Platelet Reactivity

Aspirin is used for cardiovascular disease (CVD) prevention by millions of patients on a daily basis. Previous studies suggested that aspirin intake at bedtime reduces blood pressure compared with intake on awakening. This has never been studied in patients with CVD. Moreover, platelet reactivity and CVD incidence is highest during morning hours. Bedtime aspirin intake may attenuate morning platelet reactivity. This clinical trial examined the effect of bedtime aspirin intake compared with intake on awakening on 24-hour ambulatory blood pressure measurement and morning platelet reactivity in patients using aspirin for CVD prevention. In this randomized open-label crossover trial, 290 patients were randomized to take 100 mg aspirin on awakening or at bedtime during 2 periods of 3 months. At the end of each period, 24-hour blood pressure and morning platelet reactivity were measured. The primary analysis population comprised 263 (blood pressure) and 133 (platelet reactivity) patients. Aspirin intake at bedtime did not reduce blood pressure compared with intake on awakening (difference systolic/diastolic: −0.1 [95% confidence interval, −1.0, 0.9]/−0.6 [95% confidence interval, −1.2, 0.0] mm Hg). Platelet reactivity during morning hours was reduced with bedtime aspirin intake (difference: −22 aspirin reaction units [95% confidence interval, −35, −9]). The intake of low-dose aspirin at bedtime compared with intake on awakening did not reduce blood pressure of patients with CVD. However, bedtime aspirin reduced morning platelet reactivity. Future studies are needed to assess the effect of this promising simple intervention on the excess of cardiovascular events during the high risk morning hours.

Comparison of a morning polypill, evening polypill and individual pills on LDL-cholesterol, ambulatory blood pressure and adherence in high-risk patients; a randomized crossover trial

AIMS

Cardiovascular polypills are a novel strategy in the prevention of cardiovascular disease. Based on considerations about the effectiveness, the individual pills of a polypill are taken at different times of the day. This study aimed therefore to compare the use of a polypill in the morning, in the evening or the individual components taken at their usual times on cardiovascular risk factors and patient acceptability.

METHODS

The study was a randomized three-period crossover trial. Seventy-eight patients with established cardiovascular disease were randomly allocated to the use of polypill (aspirin 75 mg, simvastatin 40 mg, lisinopril 10mg and hydrochlorothiazide 12.5mg) in the morning, in the evening or use of the individual agents taken at different time points (Trial: NCT01506505).

RESULTS

Using the polypill in the evening resulted in a 0.2 mmol/L (95%-confidence interval (CI): 0.1 to 0.3) lower fasting LDL-cholesterol compared to the use in the morning, and not statistically significantly different mean 24-hour systolic BP (mean difference: 0.7 mmHg; 95%-CI; -2.1 to 3.4). Compared to the use of the individual agents, the mean LDL-cholesterol was 0.2 mmol/L (95%-CI: 0.1 to 0.3) higher when using the polypill in the morning, but not statistically significantly different when used in the evening (mean difference: -0.1 mmol/L; 95%-CI: -0.1 to 0.0). Furthermore, there were no differences in mean 24-hour systolic BP with morning use (mean difference: 0.4 mmHg; 95%-CI; -1.5 to 2.3) or evening use (mean difference: 1.0mmHg; 95%-CI; -0.8 to 2.8) of the polypill compared to the individual agents. The adherence was 5.2% (95%-CI: 1.4 to 9.1) higher with morning use of the polypill and 5.0% (95%-CI: 1.5 to 8.5) higher with evening use compared to the individual agents. Treatment with the polypill was preferred by 92% of the participants.

CONCLUSION

The use of a polypill in the evening was more effective in lowering LDL-cholesterol, and resulted in not statistically significantly different ambulatory BP levels compared to the use of a polypill in the morning. Therapy with a polypill was associated with an increased adherence. The polypill is highly preferred by patients, demonstrating a potential role for the polypill in the prevention of cardiovascular disease.

Effect of polyphenol-rich grape seed extract on ambulatory blood pressure in subjects with pre- and stage I hypertension

Dietary polyphenols, such as those from grape products, may exert beneficial effects on cardiovascular health, including anti-hypertensive effects. We investigated the effect of a specific grape seed extract (GSE) rich in low-molecular-weight polyphenolic compounds on ambulatory blood pressure (ABP) in untreated subjects with pre- and stage I hypertension. In addition, potential mechanisms that could underlie the hypothesised effect of GSE on blood pressure (BP), and platelet aggregation, were explored. The study was designed as a double-blind, placebo-controlled, randomised, parallel-group intervention study including seventy healthy subjects with systolic BP between 120 and 159 mmHg. A 1-week run-in period was followed by an 8-week intervention period, during which subjects consumed capsules containing either 300 mg/d of GSE or a placebo (microcrystalline cellulose). Before and after the intervention, daytime ABP readings, 24 h urine samples and fasting and non-fasting blood samples were taken. The mean baseline systolic BP was 135·8 (se 1·3) mmHg and diastolic BP was 81·5 (se 0·9) mmHg. BP values were modestly, but not significantly, affected by the polyphenol-rich GSE treatment v. placebo with an effect of − 3·0 mmHg for systolic BP (95 % CI − 6·5, 0·5) and − 1·4 mmHg for diastolic BP (95 % CI − 3·5, 0·6). Vasoactive markers including endothelin-1, NO metabolites and asymmetric dimethylarginine, plasma renin activity and platelet aggregation were not affected by the GSE intervention. Our findings show that consumption of polyphenol-rich GSE does not significantly lower ABP in untreated subjects with pre- and stage I hypertension.

Problematic drinking and physiological responses among female college students

Problematic drinking is a widespread problem among college students, and can contribute to alcohol dependence during later adulthood, particularly among females. The current study assessed vulnerability for alcohol-related consequences by comparing self-reported drinking with coping styles and physiological and behavioral stress responses during a challenging task. Cardiovascular measurements and saliva samples were taken from 88 female students at the beginning of the experiment and after the task. Hypothalamic-pituitary-adrenal (HPA) activity was measured by assessing cortisol and dehydroepiandrosterone (DHEA) salivary levels. The behavioral task consisted of a set of three anagrams of increasing difficulty, the last of which had no possible solution, to test the distress tolerance of the participants. Results showed that the majority of participants (70%) reported drinking in the six months prior to data collection, most of whom reported at least one incident of binge drinking. Excessive alcohol use was related to an impaired physiological response to stress during the impossible task. College students who drank to cope with stress had significantly higher basal levels of cortisol and DHEA, an indication of HPA axis over-regulation, while their stress response remained remarkably flat. Self-reported consequences of drinking were related to motives for drinking and lower DHEA levels. Regression analysis indicated that higher cortisol levels mediated the relationship between motives for drinking and problematic drinking.

Biological rhythms and preeclampsia

The impact of impaired circadian rhythm on health has been widely studied in shift workers and trans-meridian travelers. A part from its correlation with sleep and mood disorders, biological rhythm impairment is a recognized risk factor for cardiovascular diseases and breast cancer. Preeclampsia is a major public health issue, associated with a significant maternal and fetal morbidity and mortality worldwide. While the risks factors for this condition such as obesity, diabetes, pre-existing hypertension have been identified, the underlying mechanism of this multi-factorial disease is yet not fully understood. The disruption of the light/dark cycle in pregnancy has been associated with adverse outcomes. Slightly increased risk for "small for gestational age" babies, "low birth weight" babies, and preterm deliveries has been reported in shift working women. Whether altered circadian cycle represents a risk factor for preeclampsia or preeclampsia is itself linked with an abnormal circadian cycle is less clear. There are only few reports available, showing conflicting results. In this review, we will discuss recent observations concerning circadian pattern of blood pressure in normotensive and hypertensive pregnancies. We explore the hypothesis that circadian misalignments may represent a risk factor for preeclampsia. Unraveling potential link between circadian clock gene and preeclampsia could offer a novel approach to our understanding of this multi-system disease specific to pregnancy.

Administration-time differences in effects of hypertension medications on ambulatory blood pressure regulation

Specific features of the 24-h blood pressure (BP) pattern are linked to progressive injury of target tissues and risk of cardiovascular disease (CVD) events. Several studies have consistently shown an association between blunted asleep BP decline and risk of fatal and nonfatal CVD events. Thus, there is growing focus on ways to properly control BP during nighttime sleep as well as during daytime activity. One strategy, termed chronotherapy, entails the timing of hypertension medications to endogenous circadian rhythm determinants of the 24-h BP pattern. Significant and clinically meaningful treatment-time differences in the beneficial and/or adverse effects of at least six different classes of hypertension medications, and their combinations, are now known. Generally, calcium channel blockers (CCBs) are more effective with bedtime than morning dosing, and for dihydropyridine derivatives bedtime dosing significantly reduces risk of peripheral edema. The renin-angiotensin-aldosterone system is highly circadian rhythmic and activates during nighttime sleep. Accordingly, evening/bedtime ingestion of the angiotensin-converting enzyme inhibitors (ACEIs) benazepril, captopril, enalapril, lisinopril, perindopril, quinapril, ramipril, spirapril, trandolapril, and zofenopril exerts more marked effect on the asleep than awake systolic (SBP) and diastolic (DBP) BP means. Likewise, the bedtime, in comparison with morning, ingestion schedule of the angiotensin-II receptor blockers (ARBs irbesartan, olmesartan, telmisartan, and valsartan exerts greater therapeutic effect on asleep BP, plus significant increase in the sleep-time relative BP decline, with the additional benefit, independent of drug terminal half-life, of converting the 24-h BP profile into a more normal dipping pattern. This is the case also for the bedtime versus upon-awakening regimen of combination ARB-CCB, ACEI-CCB, and ARB-diuretic medications. The chronotherapy of conventional hypertension medications constitutes a new and cost-effective strategy for enhancing the control of daytime and nighttime SBP and DBP levels, normalizing the dipping status of their 24-h patterning, and potentially reducing the risk of CVD events and end-organ injury, for example, of the blood vessels and tissues of the heart, brain, kidney, and retina.

Is there a BP benefit of changing the time of aspirin administration in treated hypertensive patients?

Background and design: The effects of aspirin on blood pressure (BP) are controversial and a chronopharmacological effect of aspirin on 24-hour BP was reported recently in otherwise untreated hypertensive patients. The study was designed to test the timing effect of aspirin dosing on 24-hour BP in treated hypertensive patients routinely taking aspirin for cardiovascular prevention.

Method and results: Seventy-five patients were randomized into two groups. One group was to receive aspirin in the evening then in the morning for 1 month and the other group in the morning then in the evening, following a cross-over design. The principal assessment criterion was 24-hour systolic BP (SBP) measured by 24-hour ambulatory BP monitoring (ABPM). Patients were aged 65 ± 9 years and had been hypertensive for 12 ± 10 years. They were all taking a mean of 2.8 antihypertensive drugs and did not modify their treatment throughout the study. Of the included subjects, 70% were men and 33% were diabetics. Mean 24-hour SBP values were clinically equivalent and were not statistically different, depending on whether the aspirin was taking in the morning or evening (128.3 ± 1.4 vs. 128.3 ± 1.4 mmHg, respectively). Neither was there any significant difference in diurnal and nocturnal SBP or in 24-hour, diurnal, and nocturnal diastolic BP (DBP).

Conclusion: It does not appear useful to advise patients with long-standing hypertension to modify timing of aspirin intake in order to reduce BP values.