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

Comparison between valsartan and valsartan plus cilnidipine in type II diabetics with normo- and microalbuminuria

Cilnidipine, an L-/N-type calcium channel blocker, dilates the efferent glomerular arterioles in an experimental model and shows a renoprotective effect, but its clinical benefits and safety have not yet been assessed in type II diabetics with albuminuria. The objective of this trial was to evaluate the effect of reducing albuminuria in type II diabetic patients with a combination therapy consisting of valsartan plus cilnidipine versus monotherapy with valsartan. An open-label, randomized controlled trial was conducted from April 2002 to October 2003 in 87 Japanese patients aged 31-90 years with type II diabetes showing albuminuria (urinary albumin/creatinine ratio: 10-300 mg/g). The patients were randomized to receive either valsartan (n=41) or valsartan plus cilnidipine (n=46) once daily for 1 year. The primary end point was the percent change in the albumin/creatinine ratio. The secondary end points were the progression/regression of albuminuria, blood pressure (BP), renal function, and safety. After 1 year, the albumin/creatinine ratio was found to have decreased more markedly in the valsartan plus cilnidipine group than in the valsartan group (reduction rate -44+/-11% (s.e.) versus -9+/-7% (s.e.); P=0.014 by analysis of covariance). Although a significant reduction was observed in the systolic and diastolic BP of both groups from baseline to 1 year (P<0.0001, respectively), there was no significant difference in the change in the BP between the two groups (systolic BP, P=0.066; diastolic BP, P=0.391). There were also no significant differences in the side effects between the two groups. Cilnidipine was thus found to show an additive effect with valsartan and thereby caused a reduction in albuminuria in type II diabetics.

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.

Enzyme linked immunosorbent assay for determination of amlodipine in plasma

Amlodipine is a calcium channel antagonist of the dihydropyridine group. It is effective for treating hypertension, chronic stable angina, and vasospastic angina. However, it is difficult clinically to pinpoint the maximum dosage for antihypertensive activity of the drug without having parallel data on the plasma drug concentrations. The methods for assaying amlodipine are either gas chromatography with electron capture detector or liquid chromatography coupled with tandem mass spectrometry (or with an electrochemical detector), which needs tedious derivatization, and is expensive and time consuming. Therefore, in this study we developed an enzyme immunoassay for determining amlodipine in plasma. Anti-amlodipine antibodies were produced following immunization of bovine serum albumin-amlodipine conjugate. These specific antibodies were used in a competitive biotin-avidin-based enzyme-linked immunosorbent assay to measure amlodipine in plasma. Biotin was linked to the antibodies in order to enhance the sensitivity of the assay. The assay was specific for the free form of amlodipine with a detection limit of 0.1 ng/ml and the intra- and interassay coefficient of variation ranged from 1.6-10.2%. This immunoassay provides a sensitive, reliable, rapid, and accurate method for determination of amlodipine in plasma, which can be used in therapeutic drug monitoring pharmacokinetic studies and pharmaceutical analysis.

Is initial dose titration of amlodipine worthwhile in patients with mild to moderate hypertension?

Amlodipine, a dihydropyrimidine calcium antagonist, is effective in the treatment of patients with mild to moderate hypertension at doses of 5-10 mg daily. The aim of the study reported here was to determine whether an early increase in dosage of amlodipine provided an advantage in terms of antihypertensive effect. This was a single-blind, randomised study in 115 patients with mild to moderate hypertension (diastolic blood pressure 95-114 mmHg) conducted at 10 centres with two parallel groups. Group I received amlodipine 5 mg once daily for the entire 10-week treatment period, while group II received amlodipine 5 mg once daily for two weeks, with the option to increase the dose to 10 mg once daily were the diastolic blood pressure to exceed 90 mmHg. The dose was increased in 40% of group II patients (20/50). Diastolic and systolic blood pressure decreased steadily until the end of the sixth week of treatment in both groups, with no statistically significant difference between the groups. The response rate (diastolic blood pressure < or = 90 mmHg) at the end of treatment was 84% in both groups. Because there is no advantage in an early increase in dosage of amlodipine in terms of antihypertensive effect, a dose increase should not be considered until after six weeks of treatment at 5 mg once daily.