Calcium antagonists as first-choice therapy for low-renin essential hypertension

Hypertension control among euvolemic hypertensive hemodialysis patients in Malaysia: a prospective follow-up study

Objectives

Existing literature does not provide enough information on evaluation of factors associated with pre-dialysis controlled hypertension among euvolemic hemodialysis (HD) patients. We conducted a study to evaluate the rate and factors influencing pre-dialysis controlled hypertension among euvolemic HD patients.

Design

A multicenter prospective follow-up study.

Setting

Tertiary care teaching hospital and its associated private dialysis centers.

Participants

This study included 145 euvolemic eligible hypertensive patients. Various sociodemographic, clinical factors and drugs were investigated and analyzed by using appropriate statistical methods to determine the factors influencing hypertension control among the study participants.

Results

On baseline visit, the mean pre-dialysis systolic and diastolic BP (mmHg) of study participants was 161.2 ± 24. and 79.21 ± 11.8 retrospectively, and 30 (20.6%) patients were on pre-dialysis goal BP. At the end of the 6-months follow-up, the mean pre-dialysis systolic BP and diastolic BP (mmHg) of the patients was 154.6 ± 18.3 and 79.2 ± 11.8 respectively, and 42 (28.9%) were on pre-dialysis goal BP. In multivariate analysis, the use of calcium channel blockers (CCBs) was the only variable which had statistically significant association with pre-dialysis controlled hypertension at baseline (OR = 7.530, p-value = 0.001) and final (OR = 8.988, p-value < 0.001) visits.

Conclusions

In present study, the positive association observed between CCBs and controlled hypertension suggests that CCBs are effective antihypertensive drugs in the management of hypertension among euvolemic HD patients.

Strengths and limitations of this study

This study involved a group of patients from tertiary-level teaching hospital and its associated private dialysis centers of Malaysia.To the best of the authors' knowledge, this is the first study to assess the factors influencing pre-dialysis controlled hypertension in a cohort of 145 euvolemic HD patients in a Malaysian setting.For determining the factors influencing hypertenion control multivariate analysis was conducted.Being a prospective follow-up study, the findings of the present study need to be interpreted with caution since it is limited to only 6 months follow up.Nevertheless, a multicenter study with a large sample size and longer follow up time is needed to confirm the findings of the current study.

Hypertension and the vascular patient

Hypertension is intricately entwined in vascular pathology and morbidity and uncontrolled blood pressure is a leading cause of cardiovascular mortality. Unfortunately, many patients will present to the vascular surgeon with uncontrolled blood pressure elevation and yet, although vascular surgeons have been involved in treating the renovascular etiology, they seldom become actively involved in the medical management of hypertension. However, positive reinforcement by the vascular surgeon about the benefits of blood pressure control may significantly impact the patient's willingness to comply with medications. Some of these medications may also have secondary benefits such as reducing the incidence of diabetes. Accordingly modern vascular surgeons, who want to do more for their patients, need to have a basic understanding of hypertension and its treatment. This manuscript provides an overview of the modern definitions and treatment methods for primary hypertension that should provide the vascular surgeon with sufficient information to play an active role in the management of this co-morbid condition.

Antihypertensive treatment of patients with proteinuric renal diseases: risks or benefits of calcium channel blockers?

In patients with proteinuric renal diseases the rate of progression of renal insufficiency is determined by the level of blood pressure and proteinuria. It has been demonstrated that strict blood pressure control with angiotensin converting enzyme (ACE)-inhibitors or beta-blockers, aimed at reaching values below 130/80 mm Hg, attenuates the deterioration of renal function. In general, the beneficial effects of these drugs are reflected in a parallel lowering of proteinuria. Calcium channel blockers are effective antihypertensive drugs, however, their safety in patients with proteinuric renal diseases and renal insufficiency may be questioned because of reported untoward effects on urinary protein excretion. The present review discusses the potential benefits and risks of calcium channel blockers (CCBs) in the treatment of patients with renal diseases. To this end we have evaluated the effects of these drugs in animal models of progressive renal injury. In these animal models adverse effects of CCBs have been reported which are attributed to an impairment of autoregulation. In patients with proteinuria, the dihydropyridine CCBs do not lower proteinuria despite a reduction of blood pressure. Studies on the effects on the course of renal function are limited, however, the available data do suggest that this class of CCBs may be less advantageous than other antihypertensive drugs, thus arguing against the use of these agents as first-line drugs in patients with proteinuric renal diseases. Information on the effects of the non-dihydropyridine CCBs is limited to a small number of studies in patients with diabetic renal disease. Although the data suggest that these classes of CCBs might be more beneficial, more studies are needed, particularly in patients with non-diabetic renal diseases, before founded conclusions can be reached.

The natriuretic effect of nifedipine gastrointestinal therapeutic system remains despite the presence of mild-to-moderate renal failure

BACKGROUND

Calcium channel blockers facilitate the renal excretion of sodium and this effect is maintained during chronic administration of these drugs. However, it is unknown whether this natriuretic effect remains despite the presence of a decreased renal function.

OBJECTIVE

To compare the natriuretic capacity of nifedipine gastrointestinal therapeutic system (GITS) and lisinopril in patients with mild-to-moderate chronic renal failure.

METHODS

An open-label, randomized, comparative study was conducted to compare the natriuretic capacity of nifedipine GITS and lisinopril in the presence of mild-to-moderate renal failure (creatinine clearance 30-80 ml/min). After a wash-out period of 4 weeks an intravenous saline infusion (30 ml/kg of body weight of isotonic saline in 4 h) was performed and repeated after 4 weeks of active therapy. Two sex- and age-matched groups of hypertensive patients (n = 25) were included in the study. Renal failure was diagnosed as secondary to nephrosclerosis in all the patients.

RESULTS

A significant increase in the renal capacity to excrete the sodium load was observed in patients receiving nifedipine GITS (n = 11) but not in those taking lisinopril (n = 13). Both drugs controlled blood pressure to a similar extent. No changes were observed in body weight, glomerular filtration rate and renal plasma flow (measured as inulin and paraaminohippurate clearances). A significant drop was observed in urinary albumin excretion after lisinopril, but not after nifedipine. Heart rate was higher in nifedipine group.

CONCLUSION

The natriuretic capacity of nifedipine GITS remains despite the presence of mild-to-moderate chronic renal failure. Such an effect takes place in the absence of changes in renal hemodynamics, suggesting that it is caused by a direct tubular effect.

Natriuretic effect of calcium-channel blockers in hypertensives

This double-blind, randomized, crossover trial characterizes the acute natriuretic response to calcium-channel blockers (CCB) and investigates the role of hemodynamic and hormonal factors in mediating the natriuresis. Thirteen male subjects with essential hypertension received a single oral 20-mg dose of nifedipine or 120 mg of diltiazem. Renal functional and hemodynamic measurements were performed prior to and hourly for 4 hours following medication. Subjects then received these medications for 4 weeks at which time the above studies were repeated. Urinary sodium excretion increased within 60 minutes of CCB administration and the natriuresis was sustained for 4 hours. Cumulative sodium loss during the 4 hours of study was greater with nifedipine (43 +/- 12 mmol) than with diltiazem (18 +/- 6 mmol) (P less than 0.05). Despite natriuresis, urinary potassium excretion was decreased by both agents. Even though both drugs decreased the mean arterial pressure, inulin and paraaminohippurate (PAH) clearances were not altered. Plasma aldosterone concentrations decreased, plasma catecholamine concentrations increased, whereas plasma-renin activity was unchanged with both drugs. Body weight, glomerular filtration rate (GFR), renal plasma flow, plasma-renin activity, plasma aldosterone, and catecholamine concentrations were unchanged following 4 weeks of therapy. The acute natriuretic response after 4 weeks of therapy was similar to the response noted after the first dose. This study concludes that CCB are acutely natriuretic. Despite systemic hypotension, renal hemodynamics are unaltered during CCB therapy. Suppression of aldosterone as well as direct tubular effects of these drugs may mediate the natriuresis. Chronic therapy with CCB does not modify the acute natriuretic response to these agents.