Efficacy of four antihypertensive drugs (clonidine, enalapril, nitrendipine, oxprenolol) on stress blood pressure

Time course for blood pressure lowering of beta-blockers with partial agonist activity

BACKGROUND

Beta-blockers are commonly used in the treatment of hypertension. We do not know whether the blood pressure (BP) lowering efficacy of beta-blockers varies across the day. This review focuses on the subclass of beta-blockers with partial agonist activity (BBPAA).

OBJECTIVES

To assess the degree of variation in hourly BP lowering efficacy of BBPAA over a 24-hour period in adults with essential hypertension.

SEARCH METHODS

The Cochrane Hypertension Information Specialist searched the following databases for relevant studies up to June 2020: the Cochrane Hypertension Specialised Register; CENTRAL; 2020, Issue 5; MEDLINE Ovid; Embase Ovid; the World Health Organization International Clinical Trials Registry Platform; and ClinicalTrials.gov. We also contacted authors of relevant papers regarding further published and unpublished work. The searches had no language restrictions.

SELECTION CRITERIA

We sought to include all randomised and non-randomised trials that assessed the hourly effect of BBPAA by ambulatory monitoring, with a minimum follow-up of three weeks.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected the included trials and extracted the data. We assessed the certainty of the evidence using the GRADE approach. Outcomes included in the review were end-point hourly systolic and diastolic blood pressure (SBP and DBP) and heart rate (HR), measured using a 24-hour ambulatory BP monitoring (ABPM) device.

MAIN RESULTS

Fourteen non-randomised baseline controlled trials of BBPAA met our inclusion criteria, but only seven studies, involving 121 participants, reported hourly ambulatory BP data that could be included in the meta-analysis. Beta-blockers studied included acebutalol, pindolol and bopindolol. We judged most studies at high or unclear risk of bias for selection bias, attrition bias, and reporting bias. We judged the overall certainty of the evidence to be very low for all outcomes. We analysed and presented data by each hour post-dose. Very low-certainty evidence showed that hourly mean reduction in BP and HR visually showed an attenuation over time. Over the 24-hour period, the magnitude of SBP lowering at each hour ranged from -3.68 mmHg to -17.74 mmHg (7 studies, 121 participants), DBP lowering at each hour ranged from -2.27 mmHg to -9.34 mmHg (7 studies, 121 participants), and HR lowering at each hour ranged from -0.29 beats/min to -10.29 beats/min (4 studies, 71 participants). When comparing between three 8-hourly time intervals that correspond to day, evening, and night time hours, BBPAA was less effective at lowering BP and HR at night, than during the day and evening. However, because we judged that these outcomes were supported by very low-certainty evidence, further research is likely to have an important impact on the estimate of effect and may change the conclusion.

AUTHORS' CONCLUSIONS

There is insufficient evidence to draw general conclusions about the degree of variation in hourly BP-lowering efficacy of BBPAA over a 24-hour period, in adults with essential hypertension. Very low-certainty evidence showed that BBPAA acebutalol, pindolol, and bopindolol lowered BP more during the day and evening than at night. However, the number of studies and participants included in this review was very small, further limiting the certainty of the evidence. We need further and larger trials, with accurate recording of time of drug intake, and with reporting of standard deviation of BP and HR at each hour.

Hypertension update and cardiovascular risk reduction in physically active individuals and athletes

Hypertension is a prevalent disease worldwide. Its inadequate treatment leads to major cardiovascular complications, such as myocardial infarction, stroke, and heart failure. These conditions decrease life expectancy and are a substantial cost burden to health care systems. Physically active individuals and professional athletes are not risk free for developing this condition. Although the percentage of persons affected is substantially lower than the general population, these individuals still need to be thoroughly evaluated and blood pressure targets monitored to allow safe competitive sports participation. Regarding treatment, lifestyle modification measures should be routinely emphasized to athletes and active individuals with the same importance as for the general population. Medication treatment can be complicated because of restrictions by athletic organizations and possible limitations on maximal exercise performance. In addition, the choice of an antihypertensive drug should be made with consideration for salt and water losses that routinely occur in athletes, as well as preservation of exercise performance and endothelial function. First-line therapies for athletes and physically active individuals may be different from the general population. Some authorities believe that blocking the renin-angiotensin system with angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) is more beneficial compared with diuretics because of ACE inhibitors and ARBs being able to avoid salt and water losses. Dihydropyridine calcium channel blockers (CCBs) are another reasonable choice. Despite effects on heart rate, nondihydropyridine CCBs do not appear to impair exercise performance. beta-Blockers are not used as a first-line therapy in athletes because of effects on exercise and prohibition by the National Collegiate Athletic Association and World Anti-Doping Agency in certain sports. In this article, we address the evidence on hypertension and its related treatments in active individuals to provide recommendations that allow the best competitive sports results and reduce cardiovascular risk.

Effects of rilmenidine on 24-h rhythmicity of blood pressure and spontaneous baroreflex sensitivity in essential hypertensive subjects

OBJECTIVE

To study the effects of the centrally acting imidazoline-like compound rilmenidine on the circadian and short-term cardiovascular rhythms derived from continuous blood pressure (BP) recordings in patients with mild essential hypertension.

METHODS

This was a single-center, open study. Recordings were obtained from eight subjects, using a Portapres during two 24-h hospitalizations: the first after the inclusion visit and the second 4 weeks after starting rilmenidine treatment (1 or 2 mg/day). For circadian analysis of cardiovascular variables, 10 min were selected every hour to obtain 24 periods per subject for each session. Spontaneous baroreflex sensitivity (BRS) was estimated using the sequence technique and the cross-spectral analysis between systolic BP and interbeat intervals.

RESULTS

Rilmenidine significantly reduced the overall systolic and diastolic BP and heart rate (P < 0.001). The effects of rilmenidine on BP and heart rhythm were marked during the daytime. Rilmenidine reduced the low-frequency (LF) component of systolic BP variability throughout the 24 h. The highest values of spontaneous BRS were observed at night. Rilmenidine increased the BRS obtained by the slope of the sequence method throughout the 24-h period (P < 0.001). The LF gain was significantly increased with rilmenidine during the day and the night.

CONCLUSIONS

Rilmenidine may differentially affect the baroreflex-dependent (phasic or reflex) and the baroreflex-independent (tonic) autonomic outflow. The 24-h approach reinforced this concept, since indexes of BRS were increased throughout the 24-h period while BP was reduced during the daytime.

Use of skin conductance changes during mental stress testing as an index of autonomic arousal in cardiovascular research

Mental stress testing is used to study the cardiovascular changes caused by psychologic stress. To examine the effects of cardiac drugs on mental stress-induced changes, it is useful to attain a degree of arousal that can be replicated in serial studies. Skin conductance level, a cholinergically mediated index of arousal, was assessed for its stability in serial studies and under conditions of beta-blockade. In normal subjects, skin conductance increased in response to mental stress (p < 0.001) and was stable across three sessions. In patients with mild hypertension, skin conductance was elevated during mental stress during both placebo and nadolol therapy (p < 0.001). As expected, nadolol reduced baseline and stress-induced peak arterial pressure and heart rate but had no significant effect on skin conductance. Thus skin conductance level can serve as a stable and useful index of autonomic arousal in clinical trials, even in patients using beta-blocking medications.

Spectral analysis of blood pressure and heart rate variability in response to stress from air-jet in the Lyon rat

1. Power spectral analysis of the frequency of wave-forms of blood pressure and heart rate was used to characterize short-term fluctuations of these parameters in three strains of conscious Lyon rat, normotensive (LL and LN) and hypertensive LH. 2. A mild stress produced by means of a jet of air elicited blood pressure rises, associated with tachycardia. This response was of similar magnitude in the three strains. The stressor amplified the medium frequency (195-605 mHz) Mayer waves of blood pressure and heart rate which are under autonomic control. 3. Clonidine (10 micrograms kg-1 i.v.) lowered blood pressure and heart rate and dramatically reduced the amplitude of blood pressure and heart rate oscillations in the frequency region of 195-605 mHz. 4. A jet of air applied after clonidine administration led to blood pressure rise associated with tachycardia and enhanced oscillations in the 195-605 mHz region. 5. These results indicate that in Lyon normotensive and hypertensive rats, a mild emotional stressor elicits blood pressure and heart rate rises associated with spectral modifications reflecting sympathetic hyperactivity. Clonidine lowers blood pressure and heart rate and reduces their related variabilities. This effect is more pronounced in LH rats than in their normotensive controls. Clonidine appears to reduce the autonomic response to stress as indicated by the medium frequency oscillations.

Comparison of the effects of terazosin and enalapril on laboratory stress testing blood pressure in patients with essential hypertension

It is the current opinion that an ideal antihypertensive drug should reduce blood pressure (BP) not only at rest but also during stressful situations. The current study was aimed to compare the effects of the selective alpha 1-adrenergic blocker terazosin (5 mg once daily) and of the angiotensin-converting enzyme inhibitor enalapril (20 mg once daily) on cardiovascular response to a set of standardized laboratory stressors, such as mental arithmetic, handgrip test and cycle ergometry, in a group of 16 essential hypertensive patients. The study was a randomized, double-blind, cross-over trial preceded by a placebo run-in period. Terazosin and enalapril had a comparable effect on resting BP, reducing systolic (SBP) and diastolic (DBP) blood pressure from 159.5 +/- 13.9/101.6 +/- 8.8 mm Hg during placebo by 7.8%/6.7% and by 11.3%/10.2%, respectively. The "response" rate to the two treatments was approximately the same, being 69% and 75% after terazosin and enalapril, respectively. During mental arithmetic, from an average of 181.6 +/- 17.8/118.6 +/- 11.5 mm Hg during placebo, BP was reduced by 11.5%/7.9% after terazosin and by 13.6%/8.5% after enalapril; during handgrip test, BP decreased from 207.2 +/- 22.2/142.2 +/- 13.6 mm Hg by 7.3%/8.4% after terazosin and by 7.7%/7.1% after enalapril; finally, during cycle ergometry, terazosin and enalapril lowered BP by 5.4%/6.7% and 7%/3.1%, respectively, from a placebo value of 215.5 +/- 17.3/127.6 +/- 11.2. No significant difference in antihypertensive efficacy was observed between the two drugs, either at rest and during stress testing.(ABSTRACT TRUNCATED AT 250 WORDS)

Enalapril. A reappraisal of its pharmacology and therapeutic use in hypertension

Enalapril, an angiotensin converting enzyme (ACE) inhibitor usually administered orally once daily, decreases blood pressure by lowering peripheral vascular resistance without increasing heart rate or output. It is effective in lowering blood pressure in all grades of essential and renovascular hypertension. Patients not responding adequately to enalapril monotherapy usually respond with the addition of a thiazide diuretic (or a calcium antagonist or beta-blocker), and rarely require a third antihypertensive agent. Enalapril is at least as effective as other established and newer ACE inhibitors, and members of other antihypertensive drug classes including diuretics, beta-blockers, calcium antagonists and alpha-blockers, but therapy with enalapril may be less frequently limited by serious adverse effects or treatment contraindications than with other drug classes. The most frequent adverse effect limiting all ACE inhibitor therapy in clinical practice is cough. This favourable profile of efficacy and tolerability, and the substantial weight of clinical experience, explain the increasing acceptance of enalapril as a major antihypertensive treatment and supports its use as logical first-line therapeutic option.

Elevated serum activity of N-acetyl-beta-glucosaminidase in essential hypertension: diagnostic value and reversal to normal values after antihypertensive therapy

Previous studies have shown that urinary N-acetyl-beta-glucosaminidase (NAG) is elevated in patients with hypertension, even without renal disease. To elucidate the value of measuring NAG, both in urine and serum of hypertensive patients, we measured NAG activity in the serum, plasma, and 24-hour urine by the fluorimetric method in 84 patients with uncomplicated essential hypertension before and after 6 months of effective treatment. NAG activities of these hypertensive patients were compared with those of 102 healthy normotensive subjects and 97 patients with various renal diseases and controlled hypertension. Serum NAG activity was clearly greater in patients with essential hypertension (427 +/- 124 U/mL) than in normotensive subjects (380 +/- 109 U/mL) or patients with renal disorders (393 +/- 115 U/mL) (P less than or equal to 0.004). The greater was the diastolic pressure in the hypertensive group, the greater was serum NAG activity (r = +0.30, P = 0.004). Hypertensive patients with high serum NAG activity were further characterized by a more exaggerated increase in systolic pressure (34 +/- 16 v 25 +/- 15 mm Hg, P = 0.051) and total peripheral resistance (19% +/- 18% v 12% +/- 13%, P = 0.042) in response to the cold pressor test and by a greater increase in systolic pressure (56 +/- 15 v 45 +/- 13 mm Hg, P = 0.009) and diastolic pressure (11 +/- 7 v 6 +/- 9, P = 0.043) in response to bicycle exercise testing than the group with low serum NAG activity. In contrast, urinary NAG activity tended to be only slightly higher in patients with essential hypertension than in the normotensive control group (33 +/- 31 v 23 +/- 29 U/mg creatinine [cr], P = 0.062), whereas patients with renal diseases had clearly increased urinary NAG activity (87 +/- 105 U/mg cr) (P less than 0.001). Following effective antihypertensive therapy, serum NAG activity decreased in patients with essential hypertension to values of normotensive control subjects (from 427 +/- 124 U/mL to 386 +/- 106 U/mL, P less than 0.01). A significant decrease in serum NAG activity was observed in patients with both initially high as well as low pretreatment serum NAG activities (P less than 0.001 and P less than 0.02, respectively). Urinary NAG activity overall was unchanged by antihypertensive treatment. We conclude that in patients with mild essential hypertension, serum NAG activity was already elevated (whereas urinary NAG activity was not) and was normalized by effective antihypertensive treatment.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of clonidine on blood pressure and heart rate responses to an emotional stress in the rat: a spectral study

1. The fluctuations that underlie the spontaneous variability of blood pressure (BP) and heart rate (HR) were investigated in conscious normotensive rats using power spectral analysis. 2. Air jet stimulation determined a significant BP rise associated with a tachycardia. This environmental mild stressor amplified the 195-605 mHz oscillations of HR which are under autonomic control. No habituation to this stressor was observed since a second stimulation determined similar responses. 3. Clonidine (10 micrograms/kg, i.v.) prevented the BP rise normally associated with air jet stimulation. In addition, clonidine dramatically reduced the amplitude of BP and HR oscillations in the frequency region of 195-605 mHz. 4. It is concluded that a mild emotional stressor elicits in normotensive rats a rise in BP and HR associated with modified spectral profiles reflecting sympathetic hyperactivity. Clonidine minored the effects of stress on BP and HR variability and also prevented BP elevation.