Reduction of morning blood pressure surge after treatment with nifedipine GITS at bedtime, but not upon awakening, in essential hypertension

Chronotherapy for Hypertension: A Meta-Analysis and Systematic Review of RCTs

AIM

The aim of this study was to evaluate the efficacy of chronotherapy for patients with essential hypertension with a range of clinical characteristics.

METHODS

We searched the PubMed, EMBASE, and Cochrane Library databases for randomized controlled trials of antihypertensive therapies in which patients were randomized to morning or evening administration. The primary outcomes of the included studies were ambulatory blood pressure (BP) parameters and patient characteristics, including age, body mass index, percentage of female participants, and drug ingestion, which were described in subgroup analyses.

RESULTS

In total, 56 studies were included in the analyses. Meta-analyses and subgroup analyses revealed that specific populations of patients benefited more from bedtime dosing than from morning dosing in both 24-h or 48-h ambulatory systolic BP (SBP) and nighttime SBP, including (1) groups aged < 60 years, (2) those with body mass index ≥ 30 kg/m2, (3) studies with ≥ 50% female participants, and (4) patients receiving antihypertensive calcium channel blockers. However, when controversial data by Hermida et al. were omitted, the effects of BP controls were observed in patients with overweight, particularly obesity. Furthermore, calcium channel blockers contributed to an obvious reduction in nighttime SBP with chronotherapy.

CONCLUSIONS

Chronotherapy for hypertension may not be completely ineffective, and the clinical program and timing of medication administration can be selected according to the patient's clinical characteristics. Registration PROSPERO identifier number CRD42021292795.

Evening versus morning dosing regimen drug therapy for hypertension

BACKGROUND

Variation in blood pressure levels display circadian rhythms. Complete 24-hour blood pressure control is the primary goal of antihypertensive treatment and reducing adverse cardiovascular outcomes is the ultimate aim. This is an update of the review first published in 2011.

OBJECTIVES

To evaluate the effectiveness of administration-time-related effects of once-daily evening versus conventional morning dosing antihypertensive drug therapy regimens on all-cause mortality, cardiovascular mortality and morbidity, total adverse events, withdrawals from treatment due to adverse effects, and reduction of systolic and diastolic blood pressure in people with primary hypertension.

SEARCH METHODS

We searched the Cochrane Hypertension Specialised Register via Cochrane Register of Studies (17 June 2022), Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 6, 2022); MEDLINE, MEDLINE In-Process and MEDLINE Epub Ahead of Print (1 June 2022); Embase (1 June 2022); ClinicalTrials.gov (2 June 2022); Chinese Biomedical Literature Database (CBLD) (1978 to 2009); Chinese VIP (2009 to 7 August 2022); Chinese WANFANG DATA (2009 to 4 August 2022); China Academic Journal Network Publishing Database (CAJD) (2009 to 6 August 2022); Epistemonikos (3 September 2022) and the reference lists of relevant articles. We applied no language restrictions.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing the administration-time-related effects of evening with morning dosing monotherapy regimens in people with primary hypertension. We excluded people with known secondary hypertension, shift workers or people with white coat hypertension.

DATA COLLECTION AND ANALYSIS

Two to four review authors independently extracted data and assessed trial quality. We resolved disagreements by discussion or with another review author. We performed data synthesis and analyses using Review Manager Web for all-cause mortality, cardiovascular mortality and morbidity, serious adverse events, overall adverse events, withdrawals due to adverse events, change in 24-hour blood pressure and change in morning blood pressure. We assessed the certainty of the evidence using GRADE. We conducted random-effects meta-analysis, fixed-effect meta-analysis, subgroup analysis and sensitivity analysis.

MAIN RESULTS

We included 27 RCTs in this updated review, of which two RCTs were excluded from the meta-analyses for lack of data and number of groups not reported. The quantitative analysis included 25 RCTs with 3016 participants with primary hypertension. RCTs used angiotensin-converting enzyme inhibitors (six trials), calcium channel blockers (nine trials), angiotensin II receptor blockers (seven trials), diuretics (two trials), α-blockers (one trial), and β-blockers (one trial). Fifteen trials were parallel designed, and 10 trials were cross-over designed. Most participants were white, and only two RCTs were conducted in Asia (China) and one in Africa (South Africa). All trials excluded people with risk factors of myocardial infarction and strokes. Most trials had high risk or unclear risk of bias in at least two of several key criteria, which was most prominent in allocation concealment (selection bias) and selective reporting (reporting bias). Meta-analysis showed significant heterogeneity across trials. No RCTs reported on cardiovascular mortality and cardiovascular morbidity. There may be little to no differences in all-cause mortality (after 26 weeks of active treatment: RR 0.49, 95% CI 0.04 to 5.42; RD 0, 95% CI -0.01 to 0.01; very low-certainty evidence), serious adverse events (after 8 to 26 weeks of active treatment: RR 1.17, 95% CI 0.53 to 2.57; RD 0, 95% CI -0.02 to 0.03; very low-certainty evidence), overall adverse events (after 6 to 26 weeks of active treatment: RR 0.89, 95% CI 0.67 to 1.20; I² = 37%; RD -0.02, 95% CI -0.07 to 0.02; I² = 38%; very low-certainty evidence) and withdrawals due to adverse events (after 6 to 26 weeks active treatment: RR 0.76, 95% CI 0.47 to 1.23; I² = 0%; RD -0.01, 95% CI -0.03 to 0; I² = 0%; very low-certainty evidence), but the evidence was very uncertain.

AUTHORS' CONCLUSIONS

Due to the very limited data and the defects of the trials' designs, this systematic review did not find adequate evidence to determine which time dosing drug therapy regimen has more beneficial effects on cardiovascular outcomes or adverse events. We have very little confidence in the evidence showing that evening dosing of antihypertensive drugs is no more or less effective than morning administration to lower 24-hour blood pressure. The conclusions should not be assumed to apply to people receiving multiple antihypertensive drug regimens.

Bedtime versus morning use of antihypertensives for cardiovascular risk reduction (BedMed): protocol for a prospective, randomised, open-label, blinded end-point pragmatic trial

INTRODUCTION

Sleep-time blood pressure correlates more strongly with adverse cardiovascular events than does daytime blood pressure. The BedMed trial evaluates whether bedtime antihypertensive administration, as compared with conventional morning use, reduces major adverse cardiovascular events. METHODS AND ANALYSIS: DesignProspective randomised, open-label, blinded end-point trial.ParticipantsHypertensive primary care patients using blood pressure lowering medication and free from glaucoma.SettingCommunity primary care providers in 5 Canadian provinces (British Columbia, Alberta, Saskatchewan, Manitoba and Ontario) are mailing invitations to their eligible patients. Social media campaigns (Google, Facebook) are additionally running in the same provinces.InterventionConsenting participants are allocated via central randomisation to bedtime vs morning use of all antihypertensives.Follow-up(1) Telephone or email questionnaire at 1 week, 6 weeks, 6 months and every 6 months thereafter, and (2) accessing linked governmental healthcare databases tracking hospital and community medical services.Primary outcomeComposite of all-cause death, or hospitalisation for myocardial infarction/acute-coronary syndrome, stroke or congestive heart failure.Secondary outcomesEach primary outcome element on its own, all-cause hospitalisation or emergency department visit, long-term care admission, non-vertebral fracture, new glaucoma diagnosis, 18-month cognitive decline from baseline (via Short Blessed Test).Select other outcomesSelf-reported nocturia burden at 6 weeks and 6 months (no, minor or major burden), 1-year self-reported overall health score (EQ-5D-5L), self-reported falls, total cost of care (acute and community over study duration) and mean sleep-time systolic blood pressure after 6 months (via 24-hour monitor in a subset of 302 sequential participants).Primary outcome analysisCox proportional hazards survival analysis.Sample sizeThe trial will continue until a projected 254 primary outcome events have occurred.Current statusEnrolment ongoing (3227 randomised to date).

ETHICS AND DISSEMINATION

BedMed has ethics approval from six research ethics review boards and will publish results in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NCT02990663.

Circadian Blood Pressure Rhythm in Cardiovascular and Renal Health and Disease

Blood pressure (BP) follows a circadian rhythm, it increases on waking in the morning and decreases during sleeping at night. Disruption of the circadian BP rhythm has been reported to be associated with worsened cardiovascular and renal outcomes, however the underlying molecular mechanisms are still not clear. In this review, we briefly summarized the current understanding of the circadian BP regulation and provided therapeutic overview of the relationship between circadian BP rhythm and cardiovascular and renal health and disease.

Chronotherapy for morning blood pressure surge in hypertensive patients: a systematic review and meta-analysis

BACKGROUND

The morning blood pressure surge (MBPS) is related to an exaggerated risk of cardiovascular diseases and mortality. With increasing attention on circadian change in blood pressure and extensive use of ambulatory blood pressure monitoring (ABPM), chronotherapy that administration of medication according to biological rhythm, is reported to improve cardiovascular outcomes. The aim of this study is to evaluate the influence of chronotherapy of antihypertensive drugs upon MBPS in hypertensive patients.

METHODS

A search strategy was applied in Ovid MEDLINE, EMBASE, Cochrane (Wiley) CENTRAL Register of Controlled Trials, Cochrane Database of Systematic Reviews, and the Chinese Biomedical literature database. No language and date restrictions. Randomized controlled trials (RCT) assessing the efficacy of evening and morning administration of the same medications in adult patients with primary hypertension were included.

RESULTS

A total of ten trials, comprising 1724 participants with a mean age of 61 and 51% female, were included in this study. Combined analysis observed significant reduction of MBPS (- 5.30 mmHg, 95% CI - 8.80 to - 1.80), night-time SBP (- 2.29 mmHg, 95% CI - 4.43 to - 0.15), night-time DBP (- 1.63 mmHg, 95 %CI - 3.23 to - 0.04) and increase in night blood pressure dipping (3.23%, 95% CI 5.37 to 1.10) in evening dosage compared with traditional morning dosage of blood pressure-lowering drugs. No significant difference was found in the incidence of overall adverse effects (RR 0.65, 95% CI 0.30 to 1.41) and withdrawal due to adverse effects (RR 0.95, 95% CI 0.53 to 1.71).

CONCLUSIONS

Our study suggested that evening administration of antihypertensive medications exerted better blood pressure-lowering effect on MBPS compared with conventional morning dosage. Safety assessment also indicated that the evening regimen did not increase the risk of adverse events. However, endpoint studies need to be carried out to confirm the significance and feasibility of this treatment regimen in clinical practice.

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.

Chronotherapy for Hypertension

PURPOSE OF REVIEW

Given the emerging knowledge that circadian rhythmicity exists in every cell and all organ systems, there is increasing interest in the possible benefits of chronotherapy for many diseases. There is a well-documented 24-h pattern of blood pressure with a morning surge that may contribute to the observed morning increase in adverse cardiovascular events. Historically, antihypertensive therapy involves morning doses, usually aimed at reducing daytime blood pressure surges, but an absence of nocturnal dipping blood pressure is also associated with increased cardiovascular risk.

RECENT FINDINGS

To more effectively reduce nocturnal blood pressure and still counteract the morning surge in blood pressure, a number of studies have examined moving one or more antihypertensives from morning to bedtime dosing. More recently, such studies of chronotherapy have studied comorbid populations including obstructive sleep apnea, chronic kidney disease, or diabetes. Here, we summarize major findings from recent research in this area (2013-2017). In general, nighttime administration of antihypertensives improved overall 24-h blood pressure profiles regardless of disease comorbidity. However, inconsistencies between studies suggest a need for more prospective randomized controlled trials with sufficient statistical power. In addition, experimental studies to ascertain mechanisms by which chronotherapy is beneficial could aid drug design and guidelines for timed administration.

Treatment of hypertension with chronotherapy: is it time of drug administration?

OBJECTIVE

To review evidence for dosing antihypertensives at bedtime and possible cardiovascular risk reduction.

DATA SOURCES

A PubMed, EMBASE, and Cochrane Controlled Trials database literature search (1990-September 2014) limited to human subjects was performed using the search terms hypertension, chronotherapy, ambulatory blood pressure, morning administration, evening administration, and antihypertensives. Additional references were identified from literature citations.

STUDY SELECTION

All prospective studies assessing cardiovascular outcomes or comparing morning to evening administration of antihypertensives were selected.

DATA SYNTHESIS

Compared with morning administration, dosing one or more antihypertensive medications at bedtime helps induce a normal circadian blood pressure pattern and reduces the risk of cardiovascular disease morbidity and mortality in individuals with hypertension. Similar results have been reported in high-risk individuals with diabetes, chronic kidney disease, and resistant hypertension. A lack of diversity among studied populations and reliance on subgroup analyses are among the limitations of these data. All antihypertensive medications have not been studied in chronotherapy and do not uniformly achieve desired results. The most substantial evidence exists for medications affecting the renin-angiotensin-aldosterone system.

CONCLUSIONS

Despite growing evidence and promise as a cost-effective strategy for reducing cardiovascular risk, chronotherapy is not uniformly recommended in the treatment of hypertension. Careful selection of patients and antihypertensives for chronotherapy is required. Further investigation is needed to evaluate the definitive impact of chronotherapy on cardiovascular outcomes.

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.

Timing is important in medication administration: a timely review of chronotherapy research

BACKGROUND

Chronotherapy involves altering the timing of medication administration to improve the overall control of a disease and to minimise treatment side-effects, and is an emerging concept in the field of therapeutics.

AIM

The aim of this review is to conduct an in-depth analysis of the recent literature in order to identify and evaluate the evidence base for drug chronotherapy.

METHOD

A literature search was conducted in three databases (Medline, Embase, International Pharmaceutical Abstracts) using the search terms "Chronotherapy", "Chronopharmacology", "Chronopharmacokinetics", "Chronopharmacodynamics", "Chronoefficacy", "Chronoformulation", "Morning and Evening", "Morning and Bedtime" and their combinations. The selection criteria for the inclusion of articles in the review included currency (years 2008-Aug 2011), publication in English language, studies done in Humans and non-review articles that pertained to 'drug' therapy.

RESULTS

Our search revealed a total of 192 journal articles, of which 41 articles were selected for review. The specific hypothesis for the effectiveness of chronotherapy that was tested in these 41 studies was chronoeffectiveness (n = 34), followed by chronopharmacokinetics (n = 5), chronomodulation (n = 3) and chronopharmacodynamics (n = 2). The findings from two-thirds (n = 27) of the reviewed studies, support the notion of chronotherapy.

CONCLUSION

The review presents the scope of chronotherapy in drug utilization. We believe that the knowledge of chronotherapy is growing and the current research for chronotherapy is promisingly in the conceptualization or early experimental phase. Going forward, chronotherapy studies should also explore genetic, gender and age related differences. Preliminary screening of new drugs for chronotherapeutic potential may be a way of enhancing quality use of medicines.

Effect of valsartan with bedtime dosing on chronic kidney disease patients with nondipping blood pressure pattern

Nondipping blood pressure (BP) pattern is a potential independent risk factor for chronic kidney disease (CKD). Bedtime administration of valsartan is considered to normalize circadian rhythm and protect the kidneys and heart in CKD patients. However, more clinical trials are needed to confirm this benefit. Sixty patients with nondipping BP pattern and thirty patients with dipping BP pattern were enrolled in this study, and the patients with nondipping BP pattern were randomly divided into two groups and treated with bedtime or awakening doses of valsartan (80-320 mg). Nondipping BP patients treated with bedtime doses of valsartan showed a greater reduction in 24-hour proteinuria and bedtime proteinuria, a greater delayed decline in estimated glomerular filtration rate, and more protection against myocardial hypertrophy (P<.05) compared with patients with the nondipping BP pattern treated with the awakening dose (P<.05). This was similar to patients with dipping BP. No severe clinical complications were recorded in these patients. Valsartan with bedtime dosing in CKD patients with the nondipping BP pattern have better renal and cardiovascular protection. Antihypertensive "chronotherapy" may be useful in clinical practice for CKD patients.

A bedtime dose of ARB was better than a morning dose in improving baroreflex sensitivity and urinary albumin excretion--the J-TOP study

The hypothesis that the bedtime dosing of angiotensin receptor blocker (ARB) is superior to morning dose in improving baroreflex sensitivity (BRS) and urinary albumin/creatinine ratio (UACR) was tested in this study. Baroreflex sensitivity was measured at baseline and at 6th month (N = 109) and was found to increase in the bedtime-dose group (P = .004), but not in the morning-dose group. The correlations between the change in BRS and the change in UACR were insignificant in the morning-dose group (r = 0.17, P = .26), but were significant in the bedtime-dose group (r = -0.29, P = .04). In conclusion, the improvement of BRS could be one of the mechanisms by which bedtime dosing of ARB confers renal protection.

Benefits of once-daily therapies in the treatment of hypertension

In patients with hypertension, 24-hour blood pressure control is the major therapeutic goal. The number of daily doses is one characteristic of an antihypertensive agent that may affect the adequacy of 24-hour control. One measure of therapeutic coverage is the 24-hour trough-to-peak ratio, which determines the suitability of an agent for once-daily administration. The closer an agent is to a 100% trough-to-peak ratio, the more uniform the 24-hour coverage and therefore blood pressure control. High trough-to-peak ratio, long-acting antihypertensive medications lower blood pressure more gradually, which reduces the likelihood of adverse events attributable to abrupt drug action that occurs with shorter-acting agents. In hypertension, the natural diurnal variation of blood pressure may be altered, including elevated nighttime pressures. An optimal once-daily hypertension therapy would not only lower blood pressure but also normalize any blunted circadian variations in blood pressure. The benefits of once-daily agents with sustained therapeutic coverage may also be explained, in part, by increased patient adherence to simpler regimens as well as lower loss of blood pressure control during virtually inevitable intermittent noncompliance. Studies have demonstrated that once-daily antihypertensive agents have the highest adherence compared with twice-daily or multiple daily doses, including greater adherence to the prescribed timing of doses.

Evening versus morning dosing regimen drug therapy for hypertension

BACKGROUND

Variation in blood pressure levels display circadian rhythms. The morning surge in blood pressure is known to increase the risk of myocardial events in the first several hours post awakening. A systematic review of the administration-time-related-effects of evening versus morning dosing regimen of antihypertensive drugs in the management of patients with primary hypertension has not been conducted.

OBJECTIVES

To evaluate the administration-time-related-effects of antihypertensive drugs administered as once daily monotherapy in the evening versus morning administration regimen on all cause mortality, cardiovascular morbidity and reduction of blood pressure in patients with primary hypertension.

SEARCH STRATEGY

We searched Cochrane CENTRAL on Ovid (4th Quarter 2009), Ovid MEDLINE (1950 to October 2009), EMBASE (1974 to October 2009), the Chinese Biomedical literature database (1978 to 2009) and the reference lists of relevant articles. No language restrictions were applied.

SELECTION CRITERIA

Randomized controlled trials comparing the administration-time-related effects of evening with morning dosing monotherapy regimens in patients with primary hypertension were included. Patients with known secondary hypertension, shift workers or white coat hypertension were excluded.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed trial quality. Disagreements were resolved by discussion or a third reviewer. Data synthesis and analysis were done using RevMan 5.1. Random effects meta-analysis and sensitivity analysis were conducted.

MAIN RESULTS

21 randomized controlled trials (RCTs) in 1,993 patients with primary hypertension met the inclusion criteria for this review - ACEIs (5 trials), CCBs (7 trials), ARBs (6 trials), diuretics (2 trials), alpha-blockers (1 trial), and beta-blockers (1 trial). Meta-analysis showed significant heterogeneity across trials.No RCT reported on all cause mortality, cardiovascular mortality, cardiovascular morbidity and serious adverse events.There was no statistically significant difference for overall adverse events (RR=0.78, 95%CI: 0.37 to 1.65) and withdrawals due to adverse events (RR=0.53, 95%CI: 0.26 to 1.07).No significant differences were noted for morning SBP (-1.62 mm Hg, 95% CI: -4.19 to 0.95) and morning DBP (-1.21 mm Hg, 95% CI: -3.28 to 0.86); but 24-hour BP (SBP: -1.71 mm Hg, 95% CI: -2.78 to -0.65; DBP: -1.38 mm Hg, 95% CI: -2.13 to -0.62) showed a statistically significant difference.

AUTHORS' CONCLUSIONS

No RCT reported on clinically relevant outcome measures - all cause mortality, cardiovascular morbidity and morbidity. There were no significant differences in overall adverse events and withdrawals due to adverse events among the evening versus morning dosing regimens. In terms of BP lowering efficacy, for 24-hour SBP and DBP, the data suggests that better blood pressure control was achieved with bedtime dosing than morning administration of antihypertensive medication, the clinical significance of which is not known.

A novel measure of the power of the morning blood pressure surge from ambulatory blood pressure recordings

BACKGROUND

We defined a new measure of the morning blood pressure (BP) surge (MBPS) that is derived by the product of the rate of morning rise (RoR) and the amplitude (day-night difference) giving an effective "Power" of the BP rise (BP(Power)). We applied this method to determine whether morning BP(Power) is different in hypertensives compared to normotensives, males compared to females or altered by antihypertensive treatment.

METHODS

BP(Power), RoR, and day-night amplitude were calculated using a double logistic fit of 691 ambulatory recordings.

RESULTS

Ambulatory recordings from untreated male and female subjects showed that upper quartile (distributed by day BP, n = 100) had a 92% greater BP(Power) (P < 0.001) than the lower quartile subjects (n = 100) due to both a faster RoR and greater amplitude. Males had a 29% greater BP(Power) than females (P = 0.003). Untreated hypertensives and white coat hypertensives showed a greater morning BP(Power) (+158% and +86%, respectively) compared to matched normotensives. Subjects taking calcium channel blockers and diuretics alone or in combination with angiotensin receptor blockers had lower morning BP(Power) than those on angiotensin converting enzyme (ACE) inhibitors or angiotensin receptor antagonists alone.

CONCLUSIONS

A new measure of the MBPS, BP(Power) which is based on a mathematical estimate of the rate and amplitude of the rise, is higher in hypertensives, white coat hypertensives, and is modifiable by some specific antihypertensive therapies suggests that it may be theoretically useful to highlight those subjects at greatest risk of cardiovascular events and for determining the most benefit of antihypertensive therapy.

Cardiovascular disease, chronopharmacotherapy, and the molecular clock

Cardiovascular functions such as heart rate and blood pressure show 24h variation. The incidence of cardiovascular diseases including acute myocardial infarction and arrhythmia also exhibits diurnal variation. The center of this circadian clock is located in the suprachiasmatic nucleus in the hypothalamus. However, recent findings revealed that each organ, including cardiovascular tissues, has its own internal clock, which has been termed a peripheral clock. The functional roles played by peripheral clocks have been reported recently. Since the peripheral clock is considered to play considerable roles in the processes of cardiac tissues, the identification of genes specifically regulated by this clock will provide insights into its role in the pathogenesis of cardiovascular disorders. In addition, the discovery of small compounds that modulate the peripheral clock will help to establish chronotherapeutic approaches. Understanding the biological relevance of the peripheral clock will provide novel approaches to the prevention and treatment of cardiovascular diseases.

Novel strategies and targets for the management of hypertension

Hypertension, as the sole or comorbid component of a constellation of disorders of the cardiovascular (CV) system, is present in over 90% of all patients with CV disease and affects nearly 74 million individuals in the United States. The number of medications available to treat hypertension has dramatically increased during the past 3 decades to some 50 medications as new targets involved in the normal regulation of blood pressure have been identified, resulting in the development of new agents in those classes with improved therapeutic profiles (e.g., renin-angiotensin-aldosterone system; RAAS). Despite these new agents, hypertension is not adequately managed in approximately 30% of patients, who are compliant with prescriptive therapeutics, suggesting that new agents and/or strategies to manage hypertension are still needed. Some of the newest classes of agents have targeted other components of the RAS, for example, the selective renin inhibitors, but recent advances in vascular biology have provided novel potential targets that may provide avenues for new agent development. These newer targets include downstream signaling participants in pathways involved in contraction, growth, hypertrophy, and relaxation. However, perhaps the most unique approach to the management of hypertension is a shift in strategy of using existing agents with respect to the time of day at which the agent is taken. This new strategy, termed "chronotherapy," has shown considerable promise in effectively managing hypertensive patients. Therefore, there remains great potential for future development of safe and effective agents and strategies to manage a disorder of the CV system of epidemic proportion.