Differences between amlodipine and lisinopril in control of clinic and twenty-four hour ambulatory blood pressures

A pilot study on the effect of telmisartan & ramipril on 24 h blood pressure profile & dipping pattern in type 1 diabetes patients with nephropathy

Background & objectives:

Angiotensin converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) have been used to normalize the blood pressure and the dipping pattern in patients with type 1 diabetes mellitus (T1DM) and nephropathy. However, there are no data on the effect of the dual blockade on the dipping pattern in these subjects. We therefore, carried out this study to evaluate the effect of administrating an ACEI followed by ARB in the optimum doses in T1DM patients with nephropathy on 24 h blood pressure (BP) profile and nocturnal dipping pattern.

Methods:

An open label interventional pilot study was done during a one year period involving 30 consecutive patients who were treated with telmisartan 80 mg (0800-1000 h) for eight weeks followed by addition of ramipril 10 mg (1200-1400 h) for the next eight weeks. Ambulatory BP, dipping pattern and albumin excretion rate were studied after each phase. Twenty patients were hypertensive and 10 patients had macro- and 20 patients had microalbuminuria.

Results:

Telmisartan produced a fall in the clinic BP by 4/1.3 mm Hg (P<0.05 and P<0.362, respectively), 2/1.9 mm Hg in the mean 24 h BP, 1.4/1.1 mm Hg in the day BP and 3.7/3 mm Hg in the trough BP. Addition of ramipril to telmisartan produced a further reduction of 6.3/5.9 mm Hg in the clinic BP (P<0.001 for both), 4.3/4.2 mm Hg in the mean 24 h BP (P<0.01 and P<0.0001, respectively), 5.8/3.9 mm Hg in the day BP (P<0.01 for both), 4.2/2.5 mm Hg in the trough BP, with a reduction of clinic SBP and DBP of 10.3/7.2 mm Hg from the baseline. Telmisartan restored normal systolic dipping pattern in 33.3 per cent of the nondippers (P<0.01) but addition of ramipril was not complimentary. Hyperkalamia (>5.5 mmol/l) was observed only in 2 patients towards the end of the study.

Interpretation & conclusions:

The dual blockade with telmisartan and ramipril had complimentary effect on lowering of the BP, however, similar beneficial effect on the nocturnal dipping was not observed. Further studies with large number of subjects with longer duration of follow-up are required to validate these observations.

What is the white-coat effect and how should it be measured?

The white coat effect is conceived as a measure of the blood pressure response to a clinic visit, but there is no agreement as to exactly how it should be defined. The most widely used definition is the difference between the average clinic and daytime ambulatory blood pressures, but other methods that have been used include the difference between clinic and home pressures, measurements using ambulatory blood pressures only, clinic measurements only, and laboratory (reactivity) testing. Few studies have compared the different methods, but the reactivity method has reported bigger changes of blood pressure and heart rate than the others. The effect tends to be greater in older than younger patients, in women than in men, but is present to a greater or lesser degree in almost all hypertensive patients. It is diminished but not obliterated by drug treatment. It is not closely related to overall blood pressure variability, and does not predict cardiovascular risk. The white coat effect appears to be idiosyncratic to the clinic setting.

Effects of long-acting ACE inhibitor (temocapril) and long-acting Ca channel blocker (amlodipine) on 24-h ambulatory BP in elderly hypertensive patients

In a prospective randomised cross-over study, we compared the effects of ACE inhibitor temocapril and calcium channel blocker (CCB) amlodipine on ambulatory blood pressure in 59 asymptomatic elderly hypertensive patients (mean age 69 years). This study was performed in a cross-over fashion after a 2-week placebo period and 4 to 8 weeks each of treatment with temocapril and amlodipine. Of those 59 hypertensive patients, three patients with side effects and 10 patients whose office BPs did not achieve the target BPs were excluded, and the remaining 46 were analysed in this study: they consisted of 30 dippers, with a night time reduction in systolic BP (SBP) > or = 10% and 16 non-dippers, with reduction by < 10%. At the baseline, there were no significant differences in the office, 24-h or daytime BPs between the two groups (dippers and non-dippers). Though the office BPs and daytime BPs were successfully controlled to the same levels with both treatments and in both dipping groups, the antihypertensive effects were stronger with the CCB than with the ACE inhibitor in the night time and morning, especially in non-dippers. We conclude that even though office BPs were controlled successfully to almost the same levels, there is a possibility that these long-acting drugs have differential antihypertensive effects on night time and morning BPs among hypertensive patients with different night time BP dipping statuses.

The importance of 24-h blood pressure control

The primary goal of antihypertensive therapy is to restore blood pressure to normal levels and to prevent the complications associated with hypertension. In order to maximize these goals by improving patient compliance, clinical researchers have focused on developing antihypertensive agents that can be given once daily. These agents provide many advantages over multiple-dose daily therapies, but it should not be assumed that they are all equivalent in providing adequate blood pressure control over the full 24-h dosing interval. Ambulatory blood pressure monitoring has uncovered important differences in commonly used once-daily therapies and has provided additional insights into the cardiovascular risks associated with high blood pressure loads and blood pressure variability. In addition to ambulatory blood pressure monitoring data, the calculated trough:peak ratio provides useful information on an agent's ability to provide smooth and consistent blood pressure control. Using such assessments, it has been found that agents with a trough:peak ratio > or = 0.50 are better able to control blood pressure over the full 24h while maintaining natural circadian patterns. Ambulatory blood pressure monitoring studies assessing a recently introduced class of antihypertensive drugs, the angiotensin receptor blockers, have demonstrated 24-h efficacy with once-daily dosing, particularly with the newer agents.

Cost per millimeter of mercury lowering is a measure of economic value for antihypertensive agents

The use of pharmacoeconomic analyses to evaluate the appropriateness of treatment regimens is increasing rapidly. Trials that study the efficacy of antihypertensive agents do not often measure long-term cardiovascular morbidity and mortality, so complementary methods are needed to evaluate the cost-effectiveness of these agents. One method is to compare agents on the basis of their costs and blood pressure-lowering efficacy, producing a ratio of cost per millimeter of mercury lowering, or cost/mm Hg. This provides a simple, transparent method with which to evaluate the cost-effectiveness of antihypertensive agents. It also allows the cost-effectiveness of a blood pressure treatment to be assessed in terms of ambulatory blood pressure data. The use of cost/mm Hg requires assumptions that tolerability of agents is comparable and that blood pressure lowering is a valid surrogate for cardiovascular risk reduction. Given the emergence of new treatments that have differences in blood pressure efficacy, cost/mm Hg is likely to become increasingly used as an indicator of economic value.

Treatment of hypertensive children with amlodipine

Amlodipine, a long-acting dihydropyridine calcium channel blocking agent, was administered to 55 children (age: 11.5 +/- 5.4 years) with hypertension, 49 of whom (89%) had secondary hypertension. Efficacy was assessed by comparing pretreatment blood pressure (BP) to follow-up BP obtained in our outpatient Pediatric Nephrology clinic. Thirty-two (58%) patients achieved BP control with amlodipine alone, and 31 (55%) patients received amlodipine twice daily. Eleven patients received amlodipine as a suspension. Mean amlodipine dose was 0.16 +/- 0.12 mg/kg/day; there was an inverse relationship between patient age and amlodipine dose. Follow-up BP were significantly lower than pretreatment BP: systolic BP fell from 129 +/- 12 to 122 +/- 12 mm Hg (P = .004), and diastolic BP fell from 78 +/- 13 to 70 +/- 19 mm Hg (P = .003). A small, clinically insignificant increase in heart rate (from 91 +/- 19 beats/min to 99 +/- 26 beats/min; P = .02) occurred during amlodipine treatment. Adverse effects reported included dizziness (three patients), fatigue (two patients), flushing (two patients), and leg edema (one patient). All improved with dose reduction. We conclude that amlodipine provides effective BP control without significant adverse effects in children with hypertension, and can be used as monotherapy in most children. Young children appear to require significantly higher doses per kilogram of body weight than older children. Twice-daily dosing may be required in many children to achieve BP control. Detailed pharmacokinetic studies are needed to confirm these observations.

Renal artery stenosis as a cause of renal impairment: implications for treatment of hypertension and congestive heart failure

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