Chronotherapy in Nigerian hypertensives

Influence of administration time and sex on natriuretic, diuretic, and kaliuretic effects of diuretics

Sex differences in renal function and blood pressure have been widely described across many species. Blood pressure dips during sleep and peaks in the early morning. Similarly, glomerular filtration rate, filtered electrolyte loads, urine volume, and urinary excretion all exhibit notable diurnal rhythms, which reflect, in part, the regulation of renal transporter proteins by circadian clock genes. That regulation is sexually dimorphic; as such, sex and time of day are not two independent regulators of kidney function and blood pressure. The objective of the present study was to assess the effect of sex and administration time on the natriuretic and diuretic effects of loop, thiazide, and K⁺-sparing diuretics, which are common treatments for hypertension. Loop diuretics inhibit Na⁺-K⁺-2Cl^- cotransporters on the apical membrane of the thick ascending limb, thiazide diuretics inhibit Na⁺-Cl^- cotransporters on the distal convoluted tubule, and K⁺-sparing diuretics inhibit epithelial Na⁺ channels on the connecting tubule and collecting duct. We simulated Na⁺ transporter inhibition using sex- and time-of-day-specific computational models of mouse kidney function. The simulation results highlighted significant sex and time-of-day differences in the drug response. Loop diuretics induced larger natriuretic and diuretic effects during the active phase. The natriuretic and diuretic effects of thiazide diuretics exhibited sex and time-of-day differences, whereas these effects of K⁺-sparing diuretics exhibited a significant time-of-day difference in females only. The kaliuretic effect depended on the type of diuretics and time of administration. The present computational models can be a useful tool in chronotherapy, to tailor drug administration time to match the body's diurnal rhythms to optimize the drug effect.NEW & NOTEWORTHY Sex influences cardiovascular disease, and the timing of onset of acute cardiovascular events exhibits circadian rhythms. Kidney function also exhibits sex differences and circadian rhythms. How do the natriuretic and diuretic effects of diuretics, a common treatment for hypertension that targets the kidneys, differ between the sexes? And how do these effects vary during the day? To answer these questions, we conducted computer simulations to assess the effects of loop, thiazide, and K⁺-sparing diuretics.

Non-pharmacological interventions to achieve blood pressure control in African patients: a systematic review

OBJECTIVES

This systematic review aims to evaluate the evidence of non-pharmacological strategies to improve blood pressure (BP) control in patients with hypertension from African countries.

DESIGN

We performed a systematic review and searched Medline, Central, CINAHL and study registers until June 2020 for randomised studies on interventions to decrease BP of patients with hypertension in African countries. We assessed the study quality using the Cochrane risk of bias tool and narratively synthesised studies on non-pharmacological hypertension interventions.

SETTING

We included studies conducted in African countries.

PARTICIPANTS

Adult African patients with a hypertension diagnosis.

INTERVENTIONS

Studies on non-pharmacological interventions aiming to improve BP control and treatment adherence.

OUTCOMES

Main outcomes were BP and treatment adherence.

RESULTS

We identified 5564 references, included 23 with altogether 18 153 participants from six African countries. The studies investigated educational strategies to improve adherence (11 studies) and treatment by healthcare professionals (5 studies), individualised treatment strategies (2 studies), strategies on lifestyle including physical activity (4 studies) and modified nutrition (1 study). Nearly all studies on educational strategies stated improved adherence, but only three studies showed a clinically relevant improvement of BP control. All studies on individualised strategies and lifestyle changes resulted in clinically relevant effects on BP. Due to the type of interventions studied, risk of bias in domain blinding of staff/participants was frequent (83%). Though incomplete outcome data in 61% of the studies are critical, the general study quality was reasonable.

CONCLUSIONS

The identified studies offer diverse low-cost interventions including educative and task-shifting strategies, individualised treatment and lifestyle modifications to improve BP control. Especially trialled physical activity interventions show clinically relevant BP changes. All strategies were trialled in African countries and may be used for recommendations in evidence-based guidelines on hypertension in African settings.

PROSPERO REGISTRATION NUMBER

CRD42018075062.

Chronotherapy for reduction of cardiovascular risk

Numerous prospective studies establish that elevated asleep blood pressure (BP) constitutes a significant cardiovascular disease (CVD) risk factor, irrespective of daytime office BP measurements or awake and 24h BP measurements. Moreover, except for a small number of studies with flawed methodology, multiple clinical trials of high consistency document significantly better BP-lowering efficacy of hypertension medication and their combinations when ingested at bedtime compared to upon awakening as is customary. Additionally, recent trials conclude bedtime hypertension chronotherapy markedly reduces CVD risk not only in the general population, but also in more vulnerable patients of advanced age, with kidney disease, diabetes, or resistant hypertension. Collectively, these results call for a new definition of true arterial hypertension and its proper diagnosis and management.

New perspectives on the definition, diagnosis, and treatment of true arterial hypertension

INTRODUCTION

Office blood pressure measurements (OBPM), still used today for diagnosis and management of hypertension, fail to reveal clinically important features of the mostly predictable blood pressure (BP) 24 h pattern, and lead to >45% of individuals being misclassified. Current hypertension guidelines do not provide recommendation on when-to-treat, despite multiple prospective clinical trials documenting improved normalization of 24 h BP pattern and significant reduction in cardiovascular disease (CVD) events when hypertension medications are ingested at bedtime rather than upon waking.

AREAS COVERED

In this review, the authors discuss current evidence on the: (i) most relevant attributes of the 24 h BP pattern deterministic of CVD risk; (ii) asleep systolic BP (SBP) mean as the most significant therapeutic target for CVD risk reduction; (iii) ingestion-time differences in pharmacodynamics of BP-lowering medications as reported with high consistency in multiple clinical trials; and (iv) enhanced prevention of CVD events achieved by bedtime hypertension chronotherapy.

EXPERT OPINION

Several prospective trials consistently document asleep SBP mean and sleep-time relative SBP decline (dipping) constitute highly significant CVD risk factors, independent of OBPM. Bedtime, compared to customary upon-waking, hypertension chronotherapy reduces risk of major CVD events. Collectively, these findings call for new definition of true hypertension and, accordingly, its proper diagnosis and management.

Circadian clock-mediated regulation of blood pressure

Most bodily functions vary over the course of a 24h day. Circadian rhythms in body temperature, sleep-wake cycles, metabolism, and blood pressure (BP) are just a few examples. These circadian rhythms are controlled by the central clock in the suprachiasmatic nucleus (SCN) of the hypothalamus and peripheral clocks located throughout the body. Light and food cues entrain these clocks to the time of day and this synchronicity contributes to the regulation of a variety of physiological processes with effects on overall health. The kidney, brain, nervous system, vasculature, and heart have been identified through the use of mouse models and clinical trials as peripheral clock regulators of BP. The dysregulation of this circadian pattern of BP, with or without hypertension, is associated with increased risk for cardiovascular disease. The mechanism of this dysregulation is unknown and is a growing area of research. In this review, we highlight research of human and mouse circadian models that has provided insight into the roles of these molecular clocks and their effects on physiological functions. Additional tissue-specific studies of the molecular clock mechanism are needed, as well as clinical studies including more diverse populations (different races, female patients, etc.), which will be critical to fully understand the mechanism of circadian regulation of BP. Understanding how these molecular clocks regulate the circadian rhythm of BP is critical in the treatment of circadian BP dysregulation and hypertension.

Bedtime Blood Pressure Chronotherapy Significantly Improves Hypertension Management

Consistent evidence of numerous studies substantiates the asleep blood pressure (BP) mean derived from ambulatory BP monitoring (ABPM) is both an independent and a stronger predictor of cardiovascular disease (CVD) risk than are daytime clinic BP measurements or the ABPM-determined awake or 24-hour BP means. Hence, cost-effective adequate control of sleep-time BP is of marked clinical relevance. Ingestion time, according to circadian rhythms, of hypertension medications of 6 different classes and their combinations significantly improves BP control, particularly sleep-time BP, and reduces adverse effects.

Chronotherapy with conventional blood pressure medications improves management of hypertension and reduces cardiovascular and stroke risks

Correlation between blood pressure (BP) and target organ damage, vascular risk and long-term patient prognosis is greater for measurements derived from around-the-clock ambulatory BP monitoring than in-clinic daytime ones. Numerous studies consistently substantiate the asleep BP mean is both an independent and a much better predictor of cardiovascular disease (CVD) risk than either the awake or 24 h means. Sleep-time hypertension is much more prevalent than suspected, not only in patients with sleep disorders, but also among those who are elderly or have type 2 diabetes, chronic kidney disease or resistant hypertension. Hence, cost-effective adequate control of sleep-time BP is of marked clinical relevance. Ingestion time, according to circadian rhythms, of hypertension medications of six different classes and their combinations significantly affects BP control, particularly sleep-time BP, and adverse effects. For example, because the high-amplitude circadian rhythm of the renin-angiotensin-aldosterone system activates during nighttime sleep, bedtime vs. morning ingestion of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers better reduces the asleep BP mean, with additional benefit, independent of medication terminal half-life, of converting the 24 h BP profile into more normal dipper patterning. The MAPEC (Monitorización Ambulatoria para Predicción de Eventos Cardiovasculares) study, first prospective randomized treatment-time investigation designed to test the worthiness of bedtime chronotherapy with ⩾1 conventional hypertension medications so as to specifically target attenuation of asleep BP, demonstrated, relative to conventional morning therapy, 61% reduction of total CVD events and 67% decrease of major CVD events, that is, CVD death, myocardial infarction, and ischemic and hemorrhagic stroke. The MAPEC study, along with other earlier conducted less refined trials, documents the asleep BP mean is the most significant prognostic marker of CVD morbidity and mortality; moreover, it substantiates attenuation of the asleep BP mean by a bedtime hypertension treatment strategy entailing the entire daily dose of ⩾1 hypertension medications significantly reduces CVD risk in both general and more vulnerable hypertensive patients, that is, those diagnosed with chronic kidney disease, diabetes and resistant hypertension.

Diuretic drugs benefit patients with hypertension more with night-time dosing

OBJECTIVES

Night-time chronotherapy in antihypertensive drugs has been shown to produce better blood pressure control and protect from cardiovascular morbidity and mortality. To date, this has been proven for several drug classes excluding thiazides diuretics. Given the peculiar response of blood pressure to thiazides in black people we sought to determine whether night-time chronotherapy with thiazides produces better control as already shown with other drug classes.

METHODS

A subanalysis of a larger chronotherapy study with antihypertensive drugs in Nigerian Africans was done. The subpopulation of those whose disease was controlled after 12 weeks of diuretic monotherapy was analysed. Those who received drugs in the morning and at night were compared along control lines and some cardiac indices.

RESULTS

Both groups were similar on all scores at baseline. After 12 weeks of monotherapy patients who received drugs at night had significantly lower systolic and diastolic blood pressure though control was achieved with both morning and night-time dosing. Also the left ventricular posterior and septal walls regressed better as well as left ventricular mass in the night-time group.

CONCLUSION

Though equally effective in reducing blood pressure and cardiac indices related to hypertension, patients taking their drugs at night recorded better values. This makes diuretics equally amenable to night-time chronotherapy as other drug classes. This effect should be explored to reduce the morbidity and mortality consequences of hypertension.

Abnormalities in chronic kidney disease of ambulatory blood pressure 24 h patterning and normalization by bedtime hypertension chronotherapy

In chronic kidney disease (CKD), the prevalence of hypertension is very high, escalating with diminishing renal function. Typically, the diagnosis of hypertension and the clinical decisions regarding its treatment are based on daytime clinic blood pressure (BP) measurements. However, the correlation between BP level and target organ damage, cardiovascular risk and long-term prognosis is greater for ambulatory than clinic measurements. Moreover, evidence is consistent among numerous studies that the elevated risk and incidence of end-organ injury and fatal and non-fatal cardiovascular events are significantly associated with blunted night-time BP decline, and that the asleep BP better predicts cardiovascular events than either the awake or 24-h BP mean. The prevalence of abnormally high asleep BP is extensive in CKD, significantly increasing with its severity. In CKD, the diagnoses of hypertension and its therapeutic control are often inaccurate in the absence of complete and careful assessment of the entire 24 h, i.e. daytime and night-time, BP pattern. Accordingly, ambulatory BP monitoring should be the preferred method to comprehensively assess and decide the optimal clinical management of patients with CKD. Recent findings indicate therapeutic restoration of normal physiologic BP reduction during night-time sleep is the most significant independent predictor of decreased cardiovascular and cerebrovascular risk, both in patients with and without CKD, and is best achieved when antihypertensive medications, mainly those blocking the renin-angiotensin-aldosterone system, are routinely taken at bedtime.

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.

Ethnobotanical study of plants used in treating hypertension in Edo State of Nigeria

A study was undertaken in 12 local government areas (LGAs) of Edo State located in central southern Nigeria, representing 66.6% coverage, in order to obtain an inventory of the major medicinal plants used in folk medicine to treat arterial hypertension. One hundred and eighty nine respondents who were mainly traditional medical practitioners and were knowledgeable in the medicinal plants for treating hypertension were interviewed using semi-structured questionnaire administered by trained interviewers. The inventory of medicinal plants is summarized in a synoptic table, which contains the scientific, vernacular and common names of the plants/frequency of citation, the part of the plant and method of preparation of recipes. The study indicated 70 plants belonging to 67 genera in 43 families are commonly prescribed. Of these plants, 39 species are cultivated, 29 species grow in the wild, while only 2 both grow wild and also cultivated. Ninety three herbal antihypertensive recipes are recognized and are mainly prepared as decoctions, infusions, powders and juice. The leaf (43%) represented the dominant morphological part often included in recipes. Plants frequently included in antihypertensive recipes were Allium species, Persea americana, Acalypha godseffiana, Zingiber officinale, Sida acuta, Hunteria umbellata, Rauwolfia vomitoria, Viscum album and Aframomum melegueta.