Use of dihydropyridine calcium channel blockers in the management of hypertension in Eastern Asians: a scientific statement from the Asian Pacific Heart Association

Titration of amlodipine to higher doses: a comparison of Asian and Western experience

In this retrospective analysis, data pooled from two Phase III/IV open-label Asian studies were used to quantify the additional blood pressure efficacy achieved when titrating amlodipine from 5 mg to 10 mg in mild/moderate hypertensive patients, and compared to data pooled from three Western studies. The primary efficacy end point was the change from baseline in sitting systolic blood pressure (SBP) and diastolic blood pressure (DBP) to the specified time point (4–8 weeks, depending on the trial). For the Asian analysis (n=174), both mean SBP and DBP were significantly decreased at the final visit (SBP −13.3 mmHg, 95% confidence interval [CI] −15.5 to −11.0; DBP −9.2 mmHg, 95% CI −10.6 to −7.8; both P<0.0001). These results were similar to the Western analysis (n=369; SBP −11.5 mmHg, 95% CI −13.1 to −10.0; DBP −6.3, 95% CI −7.1 to −5.5; both P<0.0001). In summary, titration of amlodipine from 5 mg to 10 mg significantly decreased both SBP and DBP in Asian patients with mild-to-moderate hypertension.

Effects of antihypertensive treatment in Asian populations: a meta-analysis of prospective randomized controlled studies (CARdiovascular protectioN group in Asia: CARNA)

To examine the effects of antihypertensive treatment on cardiovascular disease (CVD) in Asian populations, we systematically evaluated prospective randomized studies carried out in Asia (1991-2013). We identified 18 trials with 23,215 and 21,986 hypertensive patients in the intervention (ie, strict blood pressure [BP] lowering or add-on treatment) and reference groups, respectively (mean age, 65 years; follow-up duration, 3.2 years). Analysis was performed through 1) first subgroup: eight trials that compared active antihypertensive treatment with placebo or intensive with less intensive BP control and 2) second subgroup: 10 trials that compared different antihypertensive treatments. In the first subgroup analysis, BP was reduced from 160.3/87.3 mm Hg to 140.2/78.4 mm Hg in the intervention group with a -6.7/-2.2 mm Hg (P < .001) greater BP reduction than the reference group. Compared with the reference group, the intervention group had a lower risk of composite CVD events (odd ratio [OR], 0.73; 95% confidence interval [CI], 0.66-0.81), myocardial infarction (OR, 0.79; 95% CI, 0.63-1.0), stroke (OR, 0.71; 95% CI, 0.63-0.80), and CVD mortality (OR, 0.81; 95% CI, 0.68-0.97; all P ≤ .05). In the second subgroup analysis, no difference was found for any outcome between renin-angiotensin blockers and calcium-channel blockers or diuretics. The meta-regression line among the 18 trials indicated that a 10 mm Hg reduction in systolic BP was associated with a reduced risk for composite CVD events (-39.5%) and stroke (-30.0%). Our meta-analysis shows a benefit when a BP target of less than 140/80 mm Hg is achieved in Asian hypertensives. BP reduction itself, regardless of BP lowering agents, is important for achieving CVD risk reduction.

Characteristics of hypertension in the Chinese population

In China, the prevalence of hypertension is currently 18.8 %, and a major risk factor for hypertension is unbalanced dietary sodium and potassium intakes. High dietary sodium intake may change the circadian rhythm of 24-h blood pressure, which is characterized by a higher nighttime blood pressure. The prevalence of isolated nighttime hypertension, defined as a nighttime blood pressure of at least 120 mm Hg systolic or 70 mm Hg diastolic and a daytime systolic/diastolic blood pressure less than 135/85 mm Hg, is higher in Chinese than in Europeans. The complications of hypertension are also different across ethnicities, being mainly stroke instead of myocardial infarction in Chinese. Lowering of blood pressure provides more protection against stroke than against myocardial infarction, and calcium channel blockers provide more protection against stroke than do other classes of antihypertensive drugs. Current Chinese hypertension guidelines recommend calcium channel blockers as the most suitable class of drugs of the five classes of antihypertensive drugs.

Characteristics of hypertension in Chinese and their relevance for the choice of antihypertensive drugs

According to the 4th National Nutrition and Health Survey in 2002, the prevalence of hypertension in China was 18.8%. Despite that, the treatment rate among hypertensive patients was 82%, the control rate remained low in persons with hypertension (6%), because of the low awareness in general (30%) and the low control rate among treated hypertensive patients (25%). One of the major reasons for the increasing prevalence of hypertension is unbalance of dietary sodium and potassium intakes. In the International Study of Macro/Micro-nutrients and Blood Pressure (INTERMAP), Chinese, compared with American, British, and Japanese populations, had highest dietary sodium intakes and lowest potassium intakes, leading to a two to three times higher sodium/potassium ratio. High dietary sodium intakes may change the circadian rhythm of 24 h blood pressure, which is characterized by a higher night-time blood pressure. Indeed, the prevalence of isolated night-time hypertension, defined as a night-time blood pressure of at least 120 mmHg systolic or 70 mmHg diastolic and a daytime systolic/diastolic blood pressure less than 135/85 mmHg, was higher in Chinese than in Europeans. The complications of hypertension are also different across ethnicities, being mainly stroke instead of myocardial infarction in Chinese. Blood pressure lowering provides more protection against stroke than myocardial infarction, and calcium channel blockers provide more protection against stroke than other classes of antihypertensive drugs. Current Chinese hypertension guidelines recommend calcium channel blockers as the first of the five classes of antihypertensive drugs for stage 1 and low-risk hypertension.

Suppression of aldosterone synthesis and secretion by ca(2+) channel antagonists

Aldosterone, a specific mineralocorticoid receptor (MR) agonist and a key player in the development of hypertension, is synthesized as a final product of renin-angiotensin-aldosterone system. Hypertension can be generally treated by negating the effects of angiotensin II through the use of angiotensin-converting enzyme inhibitors (ACE-Is) or angiotensin II type 1 receptor antagonists (ARBs). However, the efficacy of angiotensin II blockade by such drugs is sometimes diminished by the so-called "aldosterone breakthrough" effect, by which ACE-Is or ARBs (renin-angiotensin system (RAS) inhibitors) gradually lose their effectiveness against hypertension due to the overproduction of aldosterone, known as primary aldosteronism. Although MR antagonists are used to antagonize the effects of aldosterone, these drugs may, however, give rise to life-threatening adverse actions, such as hyperkalemia, particularly when used in conjunction with RAS inhibitors. Recently, several groups have reported that some dihydropyridine Ca(2+) channel blockers (CCBs) have inhibitory actions on aldosterone production in in vitro and in the clinical setting. Therefore, the use of such dihydropyridine CCBs to treat aldosterone-related hypertension may prove beneficial to circumvent such therapeutic problems. In this paper, we discuss the mechanism of action of CCBs on aldosterone production and clinical perspectives for CCB use to inhibit MR activity in hypertensive patients.