Crossover study of amlodipine versus nifedipine CR with home blood pressure monitoring via cellular phone: internet-mediated open-label crossover trial of calcium channel blockers for hypertension (i-TECHO trial)

Discovery and Development of Calcium Channel Blockers

In the mid 1960s, experimental work on molecules under screening as coronary dilators allowed the discovery of the mechanism of calcium entry blockade by drugs later named calcium channel blockers. This paper summarizes scientific research on these small molecules interacting directly with L-type voltage-operated calcium channels. It also reports on experimental approaches translated into understanding of their therapeutic actions. The importance of calcium in muscle contraction was discovered by Sidney Ringer who reported this fact in 1883. Interest in the intracellular role of calcium arose 60 years later out of Kamada (Japan) and Heibrunn (USA) experiments in the early 1940s. Studies on pharmacology of calcium function were initiated in the mid 1960s and their therapeutic applications globally occurred in the the 1980s. The first part of this report deals with basic pharmacology in the cardiovascular system particularly in isolated arteries. In the section entitled from calcium antagonists to calcium channel blockers, it is recalled that drugs of a series of diphenylpiperazines screened in vivo on coronary bed precontracted by angiotensin were initially named calcium antagonists on the basis of their effect in depolarized arteries contracted by calcium. Studies on arteries contracted by catecholamines showed that the vasorelaxation resulted from blockade of calcium entry. Radiochemical and electrophysiological studies performed with dihydropyridines allowed their cellular targets to be identified with L-type voltage-operated calcium channels. The modulated receptor theory helped the understanding of their variation in affinity dependent on arterial cell membrane potential and promoted the terminology calcium channel blocker (CCB) of which the various chemical families are introduced in the paper. In the section entitled tissue selectivity of CCBs, it is shown that characteristics of the drug, properties of the tissue, and of the stimuli are important factors of their action. The high sensitivity of hypertensive animals is explained by the partial depolarization of their arteries. It is noted that they are arteriolar dilators and that they cannot be simply considered as vasodilators. The second part of this report provides key information about clinical usefulness of CCBs. A section is devoted to the controversy on their safety closed by the Allhat trial (2002). Sections are dedicated to their effect in cardiac ischemia, in cardiac arrhythmias, in atherosclerosis, in hypertension, and its complications. CCBs appear as the most commonly used for the treatment of cardiovascular diseases. As far as hypertension is concerned, globally the prevalence in adults aged 25 years and over was around 40% in 2008. Usefulness of CCBs is discussed on the basis of large clinical trials. At therapeutic dosage, they reduce the elevated blood pressure of hypertensive patients but don't change blood pressure of normotensive subjects, as was observed in animals. Those active on both L- and T-type channels are efficient in nephropathy. Alteration of cognitive function is a complication of hypertension recognized nowadays as eventually leading to dementia. This question is discussed together with the efficacy of CCBs in cognitive pathology. In the section entitled beyond the cardiovascular system, CCBs actions in migraine, neuropathic pain, and subarachnoid hemorrhage are reported. The final conclusions refer to long-term effects discovered in experimental animals that have not yet been clearly reported as being important in human pharmacotherapy.

Olmesartan with azelnidipine versus with trichlormethiazide on home blood pressure variability in patients with type II diabetes mellitus

The aim of the present study was to compare the effects of olmesartan combined with azelnidipine versus olmesartan combined with trichlormethiazide, on home blood pressure (BP) and pressure variability in type II diabetes mellitus patients using home BP telemonitoring system. We performed an open-label cross-over pilot study of 28 patients with type II diabetes mellitus. Patients received combination treatment with either olmesartan 20 mg plus azelnidipine 16 mg or olmesartan 20 mg plus trichlormethiazide 1 mg for more than 6 weeks each in a cross-over method. The coefficient of morning systolic BP variability in the olmesartan plus azelnidipine group was significantly lower than that in the olmesartan plus trichlormethiazide group (6.4 ± 1.9 vs. 7.5 ± 2.6, P = .004). There were no significant differences in mean morning systolic BP between the two groups. Using home BP telemonitoring for hypertensive patients with type II diabetes, this study revealed for the first time that the olmesartan with azelnidipine combination is superior to the olmesartan with trichlormethiazide combination in reducing home BP variability.

Calcium channel blockers in cardiovascular pharmacotherapy

This paper summarizes the pharmacological properties of calcium channel blockers (CCBs), their established therapeutic uses for cardiovascular disorders and the current improvement of their clinical effects through drug combinations. Their identification resulted from study of small molecules including coronary dilators, which were named calcium antagonists. Further experiments showed that they reduced contraction of arteries by inhibiting calcium entry and by interacting with binding sites identified on voltage-dependent calcium channels. This led to the denomination calcium channel blockers. In short-term studies, by decreasing total peripheral resistance, CCBs lower arterial pressure. By unloading the heart and increasing coronary blood flow, CCBs improve myocardial oxygenation. In long-term treatment, the decrease in blood pressure is more pronounced in hypertensive than in normotensive patients. A controversy on the safety of CCBs ended after a large antihypertensive trial (ALLHAT) sponsored by the National Heart, Lung, and Blood Institute. There are two main types of CCBs: dihydopyridine and non-dihydropyridine; the first type is vascular selective. Dihydropyrines are indicated for hypertension, chronic, stable and vasospastic angina. Non-dihydropyridines have the same indications plus antiarrythmic effects in atrial fibrillation or flutter and paroxysmal supraventricular tachycardia. In addition, CCBs reduced newly formed coronary lesions in atherosclerosis. In order to reach recommended blood pressure goals, there is a recent therapeutic move by combination of CCBs with other antihypertensive agents particularly with inhibitors acting at the level of the renin-angiotensin system. They are also combined with statins. Prevention of dementia has been reported in hypertensive patients treated with nitrendipine, opening a way for further studies on CCBs' beneficial effect in cognitive deterioration associated with aging.

Effectiveness of using long-acting angiotensin II type 1 receptor blocker in Japanese obese patients with metabolic syndrome on morning hypertension monitoring by using telemedicine system (FUJIYAMA study)

AIM

Recently, obesity patients have been diagnosed as metabolic syndrome. The aim of this study was to evaluate which angiotensin type 1 receptor blockers (ARBs), telmisartan or candesartan, is superior for the control of home blood pressure (BP) in the morning when the outpatient clinic BP was well controlled in the patients with metabolic syndrome.

METHODS

The patients with metabolic syndrome were enrolled. Home BP was monitored by using a telemedicine system. After a 2- to 4-week control period to establish baseline home BP values, these patients were randomly divided into telmisartan (20-80 mg) and candesartan (4-12 mg) groups. These end points were evaluated by using the telemedicine system during steady-state active therapy. A total of 356 patients attending 60 outpatient Japanese centers were recruited.

RESULTS

On a day of active therapy, telmisartan significantly lowered both systolic and diastolic home BP in the morning to a greater extent compared to candesartan. At the end of the study, reductions in systolic and diastolic home BP in the morning, in telmisartan group were significantly larger compared to the changes in the candesartan group (systolic; Tel: 12.0 ± 8.9 versus Can: 8.1 ± 17.1 mmHg, p = 0.0292, diastolic; Tel: 7.4 ± 6.1 versus Can: 3.7 ± 6.8 mmHg, p = 0.0053). Additionally in the telmisartan treated group, LDL-cholesterol showed significant reduction (p = 0.037), but candesartan did not.

CONCLUSION

The present study by using the telemedicine system clearly demonstrated that telmisartan has a strong effect on reducing morning home BP, and a good effect on lipid metabolism in patients with metabolic syndrome.

Feasibility of regression of hypertension using contemporary antihypertensive agents

BACKGROUND

Recently, we reported that transient treatment of genetically hypertensive rats with high-dose angiotensin receptor blocker (ARB) causes regression of established hypertension. In this study, we investigated whether treatment with candesartan or nifedipine controlled-release (CR) resulted in a sustained regression of hypertension in humans.

METHODS

Patients aged 30 to 59 years with untreated stage 1 essential hypertension and a family history of hypertension were treated with the antihypertensive agents candesartan (n = 124) or nifedipine CR (n = 120). After 1 year of treatment (phase 1), the medications were tapered and discontinued (phase 2). During phase 2, home and office blood pressures were monitored for another year to assess posttreatment reoccurrence of stage 1 hypertension.

RESULTS

In phase 1, after 1 year of treatment a similarly substantial BP decrease was seen in the candesartan (-24.5/16.1 mm Hg) and nifedipine (-26.8/18.0 mm Hg) groups. In phase 2 there was a substantial reoccurrence of hypertension; at the study end, only 1 patient was able to continue without antihypertensive medication. However, a Kaplan-Meier analysis revealed a significant delay of reoccurrence of hyper tension (P = 0.0001) in the candesartan group.

CONCLUSIONS

One year of treatment with candesartan or nifedipine CR was not associated with marked regression of hypertension in humans at the standard doses used in this trial. However, withdrawal of candesartan was associated with a slightly longer delay before restarting medications. Further studies with larger doses of candesartan given over a longer time are required to determine whether such a regimen may induce sustainable and clinically relevant reversal of hypertension and alteration in its natural history.

Efficacies of Controlling Morning Blood Pressure and Protecting the Kidneys by Treatment With Valsartan and Nifedipine CR or Valsartan and Amlodipine (MONICA Study)

Background

It is controversial whether a single-pill fixed-dose combination of angiotensin II type 1 receptor blocker and calcium channel blocker (CCB) is effective for all types of hypertension.

Methods

Thirty-five patients with uncontrolled blood pressure (BP) under treatment with valsartan 80 mg/day or amlodipine 5 mg/day were enrolled. They were randomly divided into two treatment groups: a single-pill fixed-dose combination of valsartan 80 mg/day and amlodipine 5 mg/day in the morning (VA group), or valsartan 80 mg/day in the morning and nifedipine CR 20 mg/day at night (VN group), and treated for 16 weeks. If the patient did not reach the target office BP at 8 weeks, they received double doses of CCBs.

Results

In the VN group, morning diastolic BP was significantly lower than the respective values in the VA group at 8 weeks. The percentage of patients who required a double dose of CCB in the VN group was significantly lower than that in the VA group. At 16 weeks, the BP levels in both groups were significantly reduced. Urinary albumin/creatinine at 16 weeks was significantly less than that at 0 weeks in the VN group.

Conclusion

Combination therapy with valsartan and nifedipine CR may help to control morning BP and protect the kidneys.

Comparison of daily anti-hypertensive effects of amlodipine and nifedipine coat-core using ambulatory blood pressure monitoring - utility of "hypobaric curve" and "hypobaric area"

When selecting anti-hypertensives, most physicians do not consider daily blood pressure (BP) variation. To evaluate the effectiveness of anti-hypertensives on the temporal profile of BP, we proposed three new parameters obtained by ambulatory BP monitoring and evaluated these parameters by comparing 5 mg of amlodipine and 40 mg of nifedipine coat-core. Hypobaric values were determined by subtracting BP data collected before administration of the drug from those collected after drug treatment at the corresponding time of day. The hypobaric curve was drawn by plotting the hypobaric values in chronological order, with the time at which the drug was taken set as the starting point. The hypobaric area was the area encircled between the 0 mmHg level line and the hypobaric curve. For amlodipine, the hypobaric areas of systolic blood pressure (SBP) and diastolic blood pressure (DBP) were -19,110 mmHg/min and -10,695 mmHg/min, respectively. Systolic BP decreased -13.3 mmHg, and DBP BP -7.4 mmHg as daily averages. For nifedipine coat-core, the hypobaric areas of SBP and DBP were -32,235 mmHg/min and -18,150 mmHg/min, respectively. Systolic BP decreased -22.3 mmHg and DBP -12.6 mmHg as daily averages. From the hypobaric curves, the trough-to-peak ratios of amlodipine and nifedipine coat-core were measured as 0.67 and 0.60, respectively. The total anti-hypertensive power of nifedipine coat-core, measured by the hypobaric area, was 1.69 times more potent than that of amlodipine. These parameters seem to be useful for evaluating the daily temporal profile of the BP-lowering effects of anti-hypertensive drugs.

The short treatment with the angiotensin receptor blocker candesartan surveyed by telemedicine (STAR CAST) study: rationale and study design

Previous studies have shown that transient treatment of animal models of hypertension with an angiotensin receptor blocker (ARB) causes a sustained decrease in blood pressure values that persists even after the drug treatment is discontinued (J Am Soc Nephrol 12: 659-666, 2001; Nephron 91: 710-718, 2002; Hypertens Res 30: 63-75, 2007). These results have been shown to be clinically relevant by the recent TROPHY study (N Engl J Med 354: 1685-1697, 2006). We have recently found that transient treatment with an ARB may also cause regression of established hypertension in hypertensive rats (J Am Soc Nephrol 18: 157A, 2007). The Short Treatment with the Angiotensin Receptor Blocker Candesartan Surveyed by Telemedicine (STAR CAST) study is a prospective, randomized, open, blinded end-point study in patients aged 30-59 with a positive family history of hypertension that will be conducted in several centers in Japan. The aim of the study is to evaluate the antihypertensive drug withdrawal success rate, the median duration of drug withdrawal, and the changes in home and office blood pressure values in patients with mild hypertension after tapering and withdrawal of antihypertensive treatment following treatment for 1 year with the ARB candesartan or the calcium channel blocker (CCB) nifedipine slow-release. A unique feature of this study is the use of a home blood pressure monitoring telemedicine system (i-TECHO) to allow frequent evaluation of the changes in blood pressure in the trial patients. This study will be the first clinical study to examine if regression from stage 1 (mild) hypertension to prehypertension (high-normal blood pressure) is possible using an ARB or CCB.