A dose-response study of amlodipine in mild to moderate hypertension

Response surface analyses of antihypertensive effects of angiotensin receptor blockers and amlodipine or hydrochlorothiazide combination therapy in patients with essential hypertension

While previous studies have examined the dose-response characteristics of certain antihypertensive drugs alone or in combination, response surface analysis for combination therapies involving angiotensin receptor blockers (ARBs) and either amlodipine (AML) or hydrochlorothiazide (HCT) has not been explored, particularly in the context of low-dose combinations. The objectives of present study were to generate useful dose-response information for the combination of ARB/AML or ARB/HCT and to predict the blood pressure lowering effects of combination therapies compared to monotherapies. We reviewed the New Drug Application data of combination drugs of ARB/AML and ARB/HCT. Data on systolic blood pressure (SBP), from studies conducted using a factorial dose-response design over a period of 8-12 weeks, were used. The placebo-subtracted SBP change was used for analysis. Response surface analyses of the collected data were conducted using a polynomial regression model. For ARB/AML combination, the quadratic polynomial regression model containing two linear terms, two quadratic terms, and one interaction term was best fitted to the naïve pooled data. Meanwhile, for ARB/HCT combination, the best-fitted model was a quadratic model that included two linear terms and two quadratic terms. The 1/2-dose combination of these medications, compared to each monotherapy, resulted in predicted SBP reductions that were 8-30% greater. The ratio of the estimated antihypertensive effects of the combination to the expected additive effects of each component ranged from 82% to 100% of the expected effect. These results can provide a rationale for developing lower-dose combinations of ARB/AML or ARB/HCT and assist in designing clinical trials.

Once-Daily Low Inflammatory Foods Everyday (LIFE) Smoothie or the Full LIFE Diet Lowers C-Reactive Protein and Raises Plasma Beta-Carotene in 7 Days

Serum C-reactive protein (CRP), a marker of systemic inflammation, is associated with increased risk for numerous inflammation-driven chronic diseases. A prior longitudinal study showed that the Low Inflammatory Foods Everyday (LIFE) diet, which is rich in dark green leafy vegetables (DGLV), lowered CRP over a mean follow-up period of 6 months. In this retrospective study, we investigate whether patients who consume the LIFE diet or their regular diet plus one component of the LIFE diet (LIFE smoothie), experience reductions in high-sensitivity CRP (hsCRP) in 7 days. Sixteen patients in a community practice met inclusion criteria. Patient compliance was assessed by patient interviews and measurements of beta-carotene, which is abundant in DGLV. Following the interventions, CRP decreased in both the LIFE diet (−0.47 mg/L, P = .02) and smoothie groups (−1.2 mg/L, P = .04). No statistically significant difference in reduction was observed between groups ( P = .18). Plasma beta-carotene increased in both groups (+23.2, P = .02; +20.6, P = .006, respectively). These findings suggest that the LIFE diet or a regular American diet supplemented with the LIFE smoothie may quickly reduce systemic inflammation and the risk of many chronic diseases.

Peripheral edema associated with calcium channel blockers: incidence and withdrawal rate--a meta-analysis of randomized trials

OBJECTIVE

Peripheral edema is considered to be a common and annoying adverse effect of calcium channel blockers (CCBs). It has been thought to occur secondary to arteriolar dilatation causing intracapillary hypertension and fluid extravasation. We aimed to evaluate the incidence and withdrawal rate of peripheral edema with CCBs.

METHODS

A systematic search was made in PubMed, EMBASE and CENTRAL from 1980 to January 2011 for randomized clinical trials reporting peripheral edema with CCBs in patients with hypertension. Trials enrolling at least 100 patients in the CCB arm and lasting at least 4 weeks were included in the analysis. Both the incidence and withdrawal rate due to edema were pooled by weighing each trial by the inverse of the variance. Head-to-head comparison was done to evaluate the risk of edema between newer lipophilic dihydropyridine (DHP) CCBs and older DHPs.

RESULTS

One hundred and six studies with 99 469 participants, mean age 56 ± 6 years, satisfied our inclusion criteria and were included in this analysis. The weighted incidence of peripheral edema was significantly higher in the CCBs group when compared with controls/placebo (10.7 vs. 3.2%, P < 0.0001). Similarly, the withdrawal rate due to edema was higher in patients on CCBs compared with control/placebo (2.1 vs. 0.5%, P < 0.0001). Both the incidence of edema and patient withdrawal rate due to edema increased with the duration of therapy with CCBs reaching 24 and 5%, respectively, after 6 months. The risk of peripheral edema with lipophilic DHPs was 57% lower than with traditional DHPs (relative risk 0.43; 95% confidence interval 0.34-0.53; P < 0.0001). Incidence of peripheral edema in patients on DHPs was 12.3% compared with 3.1% with non-DHPs (P < 0.0001). Edema with high-dose CCBs (defined as more than half the usual maximal dose) was 2.8 times higher than that with low-dose CCBs (16.1 vs. 5.7%, P < 0.0001).

CONCLUSION

The incidence of peripheral edema progressively increased with duration of CCB therapy up to 6 months. Over the long term, more than 5% of patients discontinued CCBs because of this adverse effect. Edema rates were lower with both non-DHPs and lipophilic DHPs.

Comparison of efficacy and tolerability of amlodipine orotate versus amlodipine besylate in adult patients with mild to moderate hypertension: A multicenter, randomized, double-blind, placebo-controlled, parallel-group, 8-week follow-up, noninferiority trial

OBJECTIVE

The purpose of this study was to compare the efficacy and tolerability of amlodipine orotate with those of amlodipine besylate in Korean patients with mild to moderate hypertension.

METHODS

This multicenter, randomized, double-blind, placebo-controlled, parallel-group study was designed as a noninferiority study. To be included in the study, previously untreated patients had to have a sitting diastolic blood pressure (SiDBP) of 90 to 109 mm Hg. Previously treated patients had to discontinue their current annhypertensive medications and have a baseline SiDBP between 90 and 109 mm Hg after a 2-week washout period. Patients who met the inclusion criteria were randomly assigned to receive 5 mg amlodipine orotate or 5 mg amlodipine besylate for 8 weeks. The medication dose was doubled (10 mg QD for either amlodipine orotate or amlodipine besylate) 4 weeks after enrollment if SiDBP was >or=90 mm Hg. The primary efficacy analysis was noninferiority of the difference in mean trough SiDBP changes from baseline for amlodipin eorotate as compared with amlodipine besylate after 8 weeks of treatment. For the secondary efficacy analysis, 2 other measures were analyzed after 8 weeks of treatment. The SiDBP response rate was defined as an SiDBP measurement<90 mm Hg at the last clinical follow-up visit or an absolute reduction of >or=10 mm Hg in SiDBP from baseline until the last clinical follow-up visit. In addition, noninferiority of the difference in mean trough sitting systolic blood pressure (SiSBP) changes from baseline was analyzed for amlodipine orotate as compared with amlodipine besylate. The drug compliance rate was estimated by pillcount.

RESULTS

Eligible patients (n=109; 43 women and 66 men) were randomly assigned to receive amlodipine orotate (n=53) or amlodipine besylate (n=56). No significant differences were found in sex, age, weight, or current smoking between the groups (all, P=NS). The proportion of patients with previous antihypertensive medications was not different between the groups (47.2% [25/53] in the amlodipine orotate group and 50.0% [28/56] in the amlodipine besylate group; P=NS). No significant differences were found in baseline SiDBP (mean [SD], 100 [6] mm Hg [range, 90-109 mm Hg] in the amlodipine orotate group and 100 [6] mm Hg [range, 90-108 mm Hg] in the amlodipine besylate group; P=NS) or in baseline SiSBP (mean [SD], 149 [14] mm Hg [range, 125-179 mm Hg] in the amlodipine orotate group and 146 [10] mm Hg [range, 123-167 mm Hg] in the amlodipine besylate group; p=NS). The mean (SD) changes in SiDBP were -15.6 (6.3) mm Hg for the amlodipine orotate group and -14.5 (5.5) mm Hg for the amlodipine besylate groups was 1.1 (5.9) mm Hg (95% CI, -0.87 to infinity), and because the lower boundary of the 95% CI was greater than -5 mm Hg, amlodipine orotate was considered noninferior to amlodipine besylate. The response rate was 48 of 51 (94.1%) in the amlodipine orotate group compared with 50 (92.6%) of 54 in the amlodipine besylate group after 8 weeks of treatment (P=NS). The mean (SD) compliance rates were 97.6% (3.6%) in the amlodipine orotate group and 96.5% (4.3%) in the amlodipine besylate group (P=NS). The incidence of drug-related adverse events (AEs) was similar between the groups (1/53 [1.9%]) in the amlodipine orotate group vs 4/55 [7.3%] in the amlodipine besylate group; P=NS). The most common drug-related AE overall was peripheral edema (2/55 [3.6%]), and the most common of all the AEs was upper respiratory tract infection (4/55 [7.3%]) in the amlodipine besylate group. The most common drug-related AE was headache (1/53 [1.9%]) in the amlodipine orotate group and peripheral edema (2/55 [3.6%]) in the amlodipine besylate group. No severe AEs were found in either group.

CONCLUSION

The reduction in SiDBP after 8 weeks of amlodipine orotate treatment was noninferior to that of amlodipine besylate in these Korean patients with mild to moderate hypertension. The SiDBP response rate and the reduction in SISBP after 8 weeks of amlodipine orotate treatment were not significantly different from those of amlodipine besylate treatment. Both agents were wel tolerated.

Amlodipine 2.5???mg once daily in older hypertensives: a Brazilian multi-centre study

OBJECTIVES

The use of low-dose amlodipine has not yet been well established in the elderly. This study therefore aimed to evaluate the efficacy and tolerability of low-dose amlodipine in elderly patients with Joint National Committee VI stage I or II hypertension.

PATIENTS AND METHODS

Sixty-five hypertensive individuals (aged 66.3 +/- 5.3 years) received amlodipine 2.5 mg per day for 12 weeks before and after two periods of 4 weeks of placebo. At weeks 0, 12 and 16, patients were submitted to office, 24 h ambulatory blood pressure monitoring and home blood pressure measurement.

RESULTS

Office systolic and diastolic blood pressure showed decreases at weeks 8 (153 +/- 17, 90 +/- 9 mmHg) and 12 (152 +/- 16, 90 +/- 9 mmHg) compared with weeks 0 (164 +/- 16, 99 +/- 6 mmHg) and 16 (162 +/- 19, 95 +/- 9 mmHg). During ambulatory monitoring, a decrease was observed in the average 24 h systolic and diastolic pressure at week 12 (143 +/- 13, 86 +/- 7 mmHg) compared with weeks 0 (155 +/- 15, 93 +/- 6 mmHg) and 16 (152 +/- 16, 92 +/- 8 mmHg). A daytime and night-time reduction in systolic and diastolic pressure was observed on home blood pressure monitoring at week 12 (146 +/- 16/88 +/- 8, 144 +/- 16/93 +/- 8 mmHg) compared with weeks 0 (159 +/- 17/94 +/- 8, 161 +/- 19/93 +/- 8 mmHg) and 16 (153 +/- 16/93 +/- 8, 154 +/- 17/92 +/- 8 mmHg). Adverse reactions were infrequent.

CONCLUSIONS

Amlodipine at a dose of 2.5 mg per day showed efficacy and good tolerability in elderly hypertensives.

Antihypertensive efficacy and safety of olmesartan medoxomil compared with amlodipine for mild-to-moderate hypertension

The antihypertensive efficacy of the angiotensin II receptor blocker olmesartan medoxomil has been shown to compare favourably with that of other antihypertensive agents. This randomized, double-blind study compared the antihypertensive efficacy of the starting dose of olmesartan medoxomil with that of the calcium channel blocker amlodipine besylate (amlodipine) in subjects with mild-to-moderate hypertension. Following a 4-week, single-blind, placebo run-in period, 440 subjects aged >/=18 years were randomized to the starting dose of olmesartan medoxomil (20 mg/day), amlodipine (5 mg/day), or placebo for 8 weeks. Subjects were evaluated by 24-h ambulatory blood pressure monitoring (ABPM) and by seated cuff blood pressure (BP) measurements at trough. The primary end point was the change from baseline in mean 24-h diastolic blood pressure (DBP) by ABPM at Week 8. Secondary end points included change from baseline in mean 24-h ambulatory systolic blood pressure (SBP) at 8 weeks, change from baseline in mean seated trough cuff DBP and SBP measurements, and response and control rates for DBP <90 and <85 mmHg. Control rates for SBP <140 and <130 mmHg were also calculated. Olmesartan medoxomil and amlodipine produced significantly greater reductions in ambulatory and seated DBP and SBP compared with placebo. Mean reductions in ambulatory and seated BP were similar between the two active agents; however, in the olmesartan medoxomil group, significantly more patients achieved the SBP goal of <130 mmHg and the DBP goal of <85 mmHg. Both drugs were well tolerated at the recommended starting dose. Although amlodipine was associated with a higher incidence of oedema, this did not reach statistical significance. Olmesartan medoxomil is an effective antihypertensive agent, with BP-lowering efficacy at the starting dose similar to that of amlodipine, and is associated with more patients achieving the rigorous BP goals of SBP <130 mmHg and DBP <85 mmHg.

Effect of amlodipine on systolic blood pressure

BACKGROUND

Systolic hypertension is the most common form of hypertension, particularly in people aged >60 years. Caused by decreased compliance of large arteries, systolic hypertension is an independent risk factor for cardiovascular disease. Recent studies have demonstrated that it is more important to control systolic blood pressure (SBP) than diastolic blood pressure (DBP).

OBJECTIVE

The objective of this study was to perform a systematic literature review to examine the effectiveness of amlodipine in lowering SBP in a variety of patient subgroups and clinical settings.

METHODS

The literature review methodology included identifying, selecting, appraising, extracting, and synthesizing primary research studies. Following an a priori protocol, published literature was searched from 1980 to 2001 using 3 electronic databases. A manual review of the reference lists of recent review articles and all accepted studies was performed. Parallel-group, randomized, controlled trials that included at least 10 adults with baseline hypertension (SBP>or=140 mm Hg, DBP>or=90 mm Hg, or both), included at least 1 arm randomized to initial treatment with amlodipine monotherapy, had a minimum treatment duration of 8 weeks, and reported baseline and end-point blood pressure were included.

RESULTS

Of 696 citations identified, 85 primary studies met all inclusion criteria. Comparable treatment arms were pooled, and weightd mean SBP was calculated. In the amlodipine monotherapy arms, which included >5000 patients, SBP decreased by a mean of 17.5 mm Hg from baseline. The effect of amlodipine in reducing SBP was greater in elderly patients (age>or=60 years) and patients with author-defined isolated systolic hypertension. The dose was titrated to achieve the target blood pressure in 73 of 89 amlodipine treatment arms, whereas 16 treatment arms reported fixed doses. The median daily dose was 5 mg (range, 1.25-15 mg) in both the fixed-dose and dose-titration groups.

CONCLUSIONS

In this review of the published literature, amlodipine monotherapy was effective in reducing SBP. Antihypertensive agents such as amlodipine warrant consideration for the management of patients with inadequately controlled SBP.

A comparison of amlodipine with enalapril in the treatment of moderate/severe hypertension

1. The safety and efficacy of amlodipine vs enalapril as monotherapy was evaluated in patients with moderate/severe hypertension (supine DBP 105-125 mm Hg, SBP 140-220 mm Hg). 2. After 2 weeks placebo treatment 31 patients were randomised by the technique of minimisation in an observer-blind study to receive once daily treatment with either amlodipine (15 patients) 5-10 mg, or enalapril (16 patients) 5-20 mg for 8 weeks. The study design concluded with 2 weeks placebo treatment. In addition to clinic measurements, home blood pressure monitoring (Copal UA-251) was performed during the study. 3. Clinic supine systolic blood pressure was reduced from 177 to 152 mm Hg (amlodipine) and 183 to 169 mm Hg (enalapril) (95% CI for the intergroup difference -22.1, 0.3, P = 0.06) after 8 weeks treatment. 4. Clinic supine diastolic blood pressure was reduced from 110 to 93 mm Hg (amlodipine) and 109-102 mm Hg (enalapril) (95% CI for the intergroup difference -17.7, -2.7, P < 0.01) after 8 weeks treatment. 5. Home blood pressure recordings confirmed these reductions in blood pressure. Although the reduction in blood pressure was greater for the amlodipine treated group, the differences between treatments were not statistically significant. 6. Both drugs were reasonably well tolerated. The adverse events occurring most frequently in the amlodipine group were headache (5), peripheral oedema (3), upper respiratory infection (3) and anxiety (2). The adverse events occurring most frequently in the enalapril treated patients were headache (6), dizziness (3) and upper respiratory infection (2).

Clinical pharmacokinetics of amlodipine

Amlodipine is a dihydropyridine calcium antagonist drug with distinctive pharmacokinetic characteristics which appear to be attributable to a high degree of ionisation. Following oral administration, bioavailability is 60 to 65% and plasma concentrations rise gradually to peak 6 to 8h after administration. Amlodipine is extensively metabolised in the liver (but there is no significant presystemic or first-pass metabolism) and is slowly cleared with a terminal elimination half-life of 40 to 50h. Volume of distribution is large (21 L/kg) and there is a high degree of protein binding (98%). There is some evidence that age, severe hepatic impairment and severe renal impairment influence the pharmacokinetic profile leading to higher plasma concentrations and longer half-lives. There is no evidence of pharmacokinetic drug interactions. Amlodipine shows linear dose-related pharmacokinetic characteristics and, at steady-state, there are relatively small fluctuations in plasma concentrations across a dosage interval. Thus, although structurally related to other dihydropyridine derivatives, amlodipine displays significantly different pharmacokinetic characteristics and is suitable for administration in a single daily dose.

Dose-response relationships with antihypertensive drugs

A variety of antihypertensive drugs have been introduced into clinical practice at excessively high dose. Examples include most thiazide diuretics, propranolol, oxprenolol, atenolol, methyldopa, hydralazine and captopril. These very high doses have usually resulted from studies in which doses have been increased at regular intervals until the desired antihypertensive effect has been achieved or until unacceptable adverse effects have resulted. Frequently the starting doses were too high and the intervals between dose adjustment too short. In many cases these large doses resulted in unnecessary adverse effects--the adverse biochemical effects of thiazide diuretics, nephrotic syndrome, taste disturbances and neutropenia with captopril, the lupus syndrome with hydralazine and the central nervous system effects of methyldopa. Parallel group design with single doses and sufficient statistical power to distinguish between the upper and lower ends of the antihypertensive dose-response relationship should replace the dose-escalating design.

Amlodipine. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic use in cardiovascular disease

Amlodipine, a basic dihydropyridine derivative, inhibits the calcium influx through 'slow' channels in peripheral vascular and coronary smooth muscle cells, thus producing marked vasodilation in peripheral and coronary vascular beds. Short to medium term clinical trials indicate that amlodipine is effective as both an antianginal agent in patients with stable angina pectoris and an antihypertensive agent in patients with mild to moderate hypertension. In small comparative studies amlodipine was at least as effective as 'standard' agents, including atenolol, verapamil, hydrochlorothiazide or captopril in hypertension, and diltiazem or nadolol in angina pectoris. Amlodipine is well tolerated, and does not appear to cause some of the undesirable effects often associated with other cardiovascular agents (e.g. adverse changes in serum lipid patterns, cardiac conduction disturbances, postural hypotension). The most common adverse effects associated with amlodipine therapy--oedema and flushing--are related to the vasodilatory action of the drug, and are generally mild to moderate in severity. Thus, amlodipine seems to provide a useful alternative to other agents currently available for the treatment of essential hypertension and chronic stable angina pectoris, with certain pharmacodynamic and tolerability properties that should be advantageous in many patients.