Effects of felodipine ER and hydrochlorothiazide on blood rheology in essential hypertension--a randomized, double-blind, crossover study

Risk of amputation under diuretics in patients with or at risk of lower extremity arterial disease: A systematic review and meta-analysis

BACKGROUND

Recently, increased risk of amputation under sodium glucose cotransporter-2 inhibitors has been debated. Similar concerns have been raised with other "traditional" diuretics, more particularly in patients with or at risk of lower extremity arterial disease (LEAD).

AIM

To collect all available data on any potential risk of amputation associated with diuretics in patients with or at risk of LEAD. Additionally, we looked for other limb-related events in these patients.

METHODS

We searched in PubMed, Embase and Scopus databases up to February 2021 for references, using peripheral or lower extremity arterial disease, diuretics and amputation keywords, excluding case reports, experimental animal studies and non-English reports.

RESULTS

Among the 1376 hits identified in the databases, six studies were finally included in this review, including one cross-sectional and five longitudinal studies (total of 47,612 participants). One study was limited to thiazide diuretics, one focused on loop diuretics and the remainder mixed all diuretics. All studies reported a significant association between diuretic use and amputation risk in patients with or at high risk of LEAD. Despite some limitations in several studies, the meta-analysis showed an increased risk of amputation associated with diuretics (odds ratio: 1.75, 95% confidence interval: 1.53-1.99; P<0.001). Beyond amputation, patients with or at risk of LEAD under diuretics appeared to be at increased risk of other lower limb events, mostly in the presence of other comorbidities, including diabetes.

CONCLUSIONS

Although the amount of data in the literature is scarce, this first systematic review and meta-analysis favours an increased risk of amputation in patients with or at risk of LEAD under diuretics. Further prospective studies must be conducted to provide a better understanding of the mechanisms. Meanwhile, the use of diuretics in these patients should be parsimonious, considering alternatives whenever possible.

Potential Protective Role of Blood Pressure-Lowering Drugs on the Balance between Hemostasis and Fibrinolysis in Hypertensive Patients at Rest and During Exercise

In patients with hypertension, the triad represented by endothelial dysfunction, platelet hyperactivity, and altered fibrinolytic function disturbs the equilibrium between hemostasis and fibrinolysis and translates into a hypercoagulable state, which underlies the risk of thrombotic complications. This article reviews the scientific evidence regarding some biological effects of antihypertensive drugs, which can protect patients from the adverse consequences of hypertensive disease, improving endothelial function, enhancing antioxidant activity, and restoring equilibrium between hemostatic and fibrinolytic factors. These protective effects appear not to be mediated through blood pressure reduction and are not shared by all molecules of the same pharmacological class.

Effect of antihypertensive treatment on plasma fibrinogen and serum HDL levels in patients with essential hypertension

The influence of hypertension, and its treatment, on circulating lipid and fibrinogen (Fib) concentrations in patients with essential hypertension was investigated. The lipid profile and Fib levels were measured in 353 patients (131 men) with essential hypertension. Their median age was 60 years (range: 18-85 years). All patients had normal results from liver, renal, and thyroid function tests. There were 162 patients (45.9%) who were not receiving antihypertensive treatment. Of the remaining patients, 117 were taking 'lipid-hostile' beta-blockers, thiazide diuretics) antihypertensives and 74 were taking 'lipid-neutral' (angiotensin-converting enzyme inhibitors, calcium channel blockers, angiotensin-II receptor blockers) agents. Patients who were taking 'lipid-hostile' antihypertensive drugs had significantly higher plasma Fib concentrations when compared with those taking 'lipid-neutral' antihypertensives or those not receiving antihypertensive treatment. These differences were not attributable to established factors that influence plasma Fib levels, since when smokers and patients with diabetes mellitus and/or vascular disease were excluded, the difference remained significant. In addition, in these more homogeneous groups, patients receiving 'lipid-neutral' treatment had significantly higher serum high-density lipoprotein (HDL) cholesterol levels when compared with both those taking 'lipid-hostile' antihypertensives and untreated ones. There were no significant differences in the other lipid variables, independently of the presence/absence or the type of antihypertensives. These results suggest that antihypertensive drugs have additional effects, beyond lowering blood pressure, on other vascular risk factors, like Fib and HDL. These effects may depend on the type of drug used.

Platelet and haemorheological markers in 'high risk' hypertensives are improved by tighter blood pressure control and cardiovascular risk management: a substudy of the Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT)

OBJECTIVE

To investigate the impact of intensified cardiovascular risk management on soluble markers of platelet, endothelial and rheological function in a population of middle-aged hypertensive patients at high risk of cardiovascular complications.

DESIGN

Prospective follow-up study.

SUBJECTS AND METHODS

A total of 159 hypertensive patients [138 male, mean age 64 (+/-8) years] and 80 healthy controls were studied. Plasma levels of soluble P-selectin (sP-sel, a marker of platelet function), von Willebrand factor (vWF, an index of endothelial damage/dysfunction) and rheological indices [fibrinogen (Fib), plasma viscosity (PV), haematocrit (HCT), white blood count (WBC) and platelet count] were measured at baseline and again (in the patients) after 6 months' treatment.

RESULTS

As expected, 6 months of intensified cardiovascular risk management resulted in a significant fall in mean blood pressure (BP) and total cholesterol. It also resulted in reduced haematocrit, vWF, sP-sel, WBC and PV levels (all P < 0.001), but not plasma fibrinogen. There were no correlations between the fall in BP and the improvement in any of the research indices.

CONCLUSIONS

Intensified cardiovascular risk management results in significant improvements in indices of endothelial, platelet and rheological function in a population of hypertensives at high risk of cardiovascular events. These improvements appear to be independent of the degree of change in BP. Given the fundamental role of interactions between the endothelium and circulating blood components in the pathogenesis of hypertensive complications this may be of importance in preventing adverse cardiovascular outcomes.

Calcium antagonists and thiazide diuretics have opposite effects on blood rheology and radial artery compliance in arterial hypertension: a randomized double-blind study

In addition to their effects on blood pressure, antihypertensive agents may produce additional effects on blood rheology and arterial compliance abnormalities which may play a role in target-organ damage. However, these effects may depend only on the specific pharmacological properties of certain antihypertensive agents, and may be partly unrelated to blood pressure lowering action. We compared the effects of nitrendipine 20 mg once daily to hydrochlorothiazide 25 mg once daily in 33 mildly to moderately hypertensive and otherwise healthy patients, in a double blind parallel group trial. Blood rheology (blood fibrinogen and protein concentrations, hematocrit, plasma viscosity and whole blood viscosity at shear rates 0.2 to 128 s-1, erythrocyte deformability and aggregation) and radial artery diameter and compliance (Nius I + Finapres) were measured at baseline and after 2 months of treatment. Both drugs produced similar blood pressure lowering. Blood viscosity increased for all shear rates in the hydrochlorothiazide group and decreased in the nitrendipine treated group. Erythrocyte deformability increased in the nitrendipine but not in the thiazide group. Radial artery diameter and compliance were not different between the two groups but there was a trend towards an increase in cross-sectional compliance in the hydrochlorothiazide group and towards a decrease in the nitrendipine group. Our data show that, in mildly hypertensive patients, blood pressure control by nitrendipine produced more favourable effects on relevant rheological variables than hydrochlorothiazide. Radial artery compliance changes tended to be altered also in opposite directions by the two agents. The significance and the clinical relevance of these effects may require further investigations.

Does hypertension confer a hypercoagulable state?

Although the blood vessels are exposed to high pressures in hypertension, the main complications of hypertension (stroke and myocardial infarction) are paradoxically thrombotic rather than haemorrhagic. In keeping with Virchow's triad, patients with hypertension do demonstrate abnormalities of vessel wall (endothelial dysfunction or damage), blood constituents (abnormal levels of haemostatic factors, platelet activation and fibrinolysis) and blood flow (rheology and flow reserve), suggesting that hypertension does confer a prothrombotic or hypercoagulable state. These abnormalities appear to be related to target organ damage and long-term prognosis and are altered by treatment. The observation that satisfactory blood pressure reduction with non-drug intervention and with various classes of antihypertensive drugs does not lead to an equal reduction in heart attacks and strokes may be due in part to unfavourable effects on the hypercoagulable state in hypertension. Antihypertensive agents with particular benefits in reducing this hypercoagulable state would be likely to have additional advantages in reducing the occurrence of stroke and other thromboembolic events.

Felodipine. A review of the pharmacology and therapeutic use of the extended release formulation in cardiovascular disorders

Felodipine is a vascular-selective, dihydropyridine calcium antagonist previously investigated as a conventional tablet formulation administered twice daily. More recently considerable experience has been gained with an extended release (ER) formulation which has the convenience of once daily administration. Felodipine ER has been well studied in patients with essential hypertension. As monotherapy in mild to moderate essential hypertension, felodipine ER is at least as effective in reducing blood pressure as other calcium antagonists, beta-blockers, diuretics and ACE inhibitors, with some results favouring felodipine ER at a statistically significant level at the dosages used. It is also effective combined with controlled release metoprolol or enalapril in patients with mild to moderate essential hypertension. In patients with more severe forms of essential hypertension uncontrolled by beta-blocker and/or diuretic therapy, felodipine ER was effective as an 'add-on' therapy in placebo-controlled trials, and, at the dosages used, more effective than either sustained release nifedipine or nitrendipine. Felodipine produces effective control of blood pressure without negative effects on cardiac performance. In addition to its antihypertensive action, results suggest that felodipine therapy is associated with significant regression of left ventricular hypertrophy. Furthermore, it appears suitable for use in patients with concomitant diabetes, renal dysfunction or asthma, and is also being investigated for use in patients with congestive heart failure or angina pectoris. Felodipine ER is an effective drug for the treatment of all grades of essential hypertension, and can be used both as monotherapy and in combination with other antihypertensive agents. Further clinical experience should fully establish the long term tolerability of felodipine ER and consequently its place in therapy relative to other accepted antihypertensive drugs. However, with the convenience of once daily administration, felodipine ER is a worthwhile innovation in the treatment of hypertension.