Current concepts of pharmacotherapy in hypertension: combination calcium channel blocker therapy in the treatment of hypertension

Intraclass differences among antihypertensive drugs

The four major classes of antihypertensive drugs—diuretics, β-blockers, calcium channel blockers, and renin-angiotensin system inhibitors (including angiotensin-converting enzyme inhibitors and angiotensin receptor blockers)—have significant qualitative and quantitative differences in the adverse effects they cause. Structural and chemical differences have been identified within these classes, especially among the calcium channel blockers and, to a lesser extent, among the thiazide/thiazide-like diuretics. However, it has been more difficult to demonstrate that these differences translate into differential effects with respect to either the surrogate endpoint of blood pressure reduction or, more importantly, hypertension-related cardiovascular complications. Based on a hierarchy-of-evidence approach, differences are apparent between hydrochlorothiazide and chlorthalidone based on evidence of moderate quality. Low-quality evidence suggests atenolol is less effective than other β-blockers. However, no significant intraclass differences have been established among the other classes of antihypertensive drugs.

Efficacy and safety of dual calcium channel blockade for the treatment of hypertension: a meta-analysis

BACKGROUND

Dual calcium-channel blocker (CCB) with a dihydropyridine (DHP) and a nondihydropyridine (NDHP) has been proposed for hypertension treatment. However, the safety and efficacy of this approach is not well known.

METHODS

A MEDLINE/EMBASE/CENTRAL search for randomized clinical trials published on this topic from 1966 to February 2012 was performed. Efficacy outcomes of decrease in systolic (SBP) and diastolic (DBP) blood pressures from baseline, changes in heart rate (HR), and adverse effects were compared between dual CCB therapy vs. DHP or NDHP. SBP, DBP, and HR were expressed as weighted mean deviation (WMD).

RESULTS

A total of 6 studies with 153 patients were included. Dual CCB produced a significantly greater reduction in SBP (21.6±9.2 mmHg) from baseline than DHP (10.3±6.3 mmHg (WMD = 10.9 mmHg, P < 0.0001)) or NDHP (8.9±4.2 mmHg (WMD = 14.1 mmHg, P = 0.002)). Dual CCB therapy reduced DBP from baseline more than either monotherapy (dual CCB = 17.5±10.2 mmHg vs. DHP = 11.6±8.7 mmHg, WMD = 5.5 mmHg, P < 0.001; and NDHP = 10.5±5.6 mmHg, WMD = 5.3 mmHg, P = 0.03). Dual CCB therapy had significantly lower HR compared to DHP (P < 0.001) but was comparable to NDHP (P = 0.12) (Delta change dual CCB = -4.0±3.5 vs. DHP = -2.0±1.5 and NDHP = -6.0±5.0 beats/min). Dual CCB therapy did not increase adverse effects.

CONCLUSIONS

Dual CCB therapy lowers blood pressure significantly better than CCB monotherapy, without an increase in adverse events. However, given the lack of long-term outcome data on efficacy and safety, dual CCB therapy should be used with restraint, if at all. Large-scale long-term trials are needed to further evaluate such a strategy.

Knowledge of prescribed medication information among patients with limited English proficiency in Sri Lanka

BACKGROUND

Patients' knowledge on prescribed medications play a key role in the long term management of cardiac diseases and in determining their outcome. The present study evaluates the knowledge about prescribed medication among cardiac patients and aim to identify factors influencing knowledge.

METHODS

A descriptive-cross-sectional study was conducted among 200 adult patients attending clinics at the Cardiology Unit of the National Hospital of Sri Lanka. Knowledge assessment focused on four different sections; drug name, dose, frequency and indication. The total score of 60 was calculated by giving each component the following weighted scores; drug name = 20, indication = 20, drug dose = 10 and frequency = 10. A binary logistic regression analysis to evaluate factors associated with 'good knowledge' (total score ≥ 40) was performed.

RESULTS

Among 200 participants 56.5% (n = 113) were males. Mean age was 59.7 ± 8.2 years and a majority (n = 170, 85.0%) were older than 50 years of age. Sinhala was the primary language of 91.5% (n = 183) of participants, while English was the primary language in only two of the study participants (1.0%). Eighty four percent of the participants were educated up to secondary education or above, while 2.5% (n = 5) had no formal education. The overall knowledge (total score-60) on prescribed medications among the study population was 'poor' (score ≤ 20) in 46%, 'adequate' (score 21-40) in 36.5% and 'good' (score ≥ 40) in 17.5%. The results of the binary logistic regression analysis indicates that Secondary (OR-1.53) and Tertiary levels (OR-2.79) of education, self-reported perception of illness as being Moderate (OR-1.23) or Severe (OR-1.70) and being educated by a doctor (as reported by patients) (OR-1.69) significantly increased the odds of having a 'Good Knowledge of Drugs'. Majority of the patients were unable to read and understand the information written in English. The doctor's contributed towards educating on drug information only in 33.0% of the patients.

CONCLUSION

In a resource-poor setting in patients with Limited English Proficiency, lower level of education and misperception of illness severity resulted in reduced knowledge on prescribed medications. Furthermore, being educated by a doctor significantly improved knowledge. However the doctors' contribution at present to deliver quality health information to their patients was at an unsatisfactory level.

Pharmacologic Issues in treating hypertension in CKD

Antihypertensive drugs are prescribed to patients with CKD to slow down the rate of loss of residual kidney function; to reduce proteinuria, when present; and to protect other target organs from damage that is mediated by elevated blood pressure (BP). In most patients, a diuretic and a renin system blocking drug, such as an angiotensin-converting enzyme inhibitor, angiotensin receptor antagonist, or an aldosterone receptor antagonist are used. Often, 3 or more drugs are needed to achieve BP goals. Many drugs are eliminated through the kidney and in some cases dosage reductions are advisable to avoid adverse effects from high levels of medication. This article will review the various classes of antihypertensive drugs used in the management of high BP in patients with CKD, with an emphasis on pitfalls that arise when kidney function is impaired.

A number of marketed dihydropyridine calcium channel blockers have mineralocorticoid receptor antagonist activity

Calcium channel blockers are widely used antihypertensives. Mineralocorticoid receptor antagonists are also used to treat hypertension and heart failure. We report here that a number of widely used dihydropyridine class calcium channel blockers are able to inhibit aldosterone-induced activation of mineralocorticoid receptor. These dihydropyridines varied in the extent of their effect on mineralocorticoid receptor, with nimodipine and felodipine the most potent and amlodipine the least. In contrast, both diltiazem and verapamil, nondihydropyridine calcium channel blockers, had no effect on mineralocorticoid receptor. These dihydropyridines compete with aldosterone for binding and block aldosterone-induced coactivator recruitment to mineralocorticoid receptor. The mineralocorticoid receptor S810L mutant, which is activated by steroidal mineralocorticoid receptor antagonist such as eplerenone, is inhibited by these drugs. Furthermore, nimodipine decreased aldosterone-induced expression of the mineralocorticoid receptor target gene epithelial sodium channel gamma subunit in adrenalectomized rats, demonstrating that dihydropyridine calcium channel blockers can function as mineralocorticoid receptor antagonists in vivo. Molecular modeling indicates that dihydropyridines dock into the ligand binding domain of mineralocorticoid receptor in a consensus pose that partially overlaps with steroidal mineralocorticoid receptor antagonists. Together, our data suggest that, in addition to their calcium channel blocking activity, a number of dihydropyridine calcium channel blockers also have mineralocorticoid receptor antagonist activity at high doses, a finding which may thus prove useful for the design of novel antihypertensive drugs in the future.

Single‐ or Double‐Blind Treatment With Balsamodendron tnukul and Nifedipine in Hypertensive Patients

This study assessed and compared the effects of Balsamodendron mukul (an extract of the gum of a small tree) and nifedipine (a calcium-channel-blocking reference drug) on blood pressure, lipids, lipoproteins, and phospholipids in randomly selected patients with essential hypertension. Fifty-seven newly diagnosed hypertensive patients were randomly divided into three groups. They received either single-blind B. mukul (1.5 g/d) or single-blind nifedipine (10 mg/d) double-blind therapy with nifedipine (10 mg/d) and B. mukul (1.5 g/d) for 6 weeks. These groups were compared with control subjects. On treatment with B. mukul, levels of systolic blood pressure, diastolic blood pressure, plasma total cholesterol, low-density lipoprotein cholesterol, very low-density lipoprotein cholesterol, triglycerides, free fatty acids, and phospholipid levels were significantly reduced, and high-density lipoprotein cholesterol levels were significantly elevated, as compared with untreated hypertensive patients. Combined therapy with B. mukul and nifedipine was more beneficial than the treatment with B. mukul alone. Our study suggests that B. mukul may be an effective antihypertensive and hypolipidemic agent.

Calcium channel blockers: monotherapy and dual therapy considerations in the treatment of hypertension

The papers in this supplement speak to several of the issues pertinent to contemporary therapy with CCBs. The article by Dr Weir thoughtfully describes important pharmacokinetic and pharmacodynamic features of CCBs. In so doing he establishes the basis for combination CCB and ACE inhibitor therapy. Dr Frishman provides a scholarly description of the cardiovascular effects of CCBs and further elaborates on the distinctiveness of the various CCB subclasses. Finally, Dr Bakris et al. provides data from INVEST (INternational VErapamil-Trandolapril STudy), which shows the particular utility of a CCB and ACE inhibitor combination in bringing elderly hypertensive patients with CAD to goal BP when monotherapy

Fixed combination of manidipine and delapril in the treatment of mild to moderate essential hypertension: evaluation by 24-hour ambulatory blood pressure monitoring

This present study assessed the antihypertensive efficacy of the fixed combination of manidipine and delapril by ambulatory blood pressure monitoring in patients with hypertension inadequately controlled by monotherapy with either component. After a 2-week placebo period, 55 mild to moderate hypertensive patients were randomized to manidipine 20 mg o.d. or delapril 30 mg b.i.d. for 4 weeks. After this period, 30 patients, aged 30-76 years (18 males and 12 females) whose diastolic blood pressure was not adequately controlled (> or = 90 mmHg) by monotherapy were treated with the fixed combination of manidipine 10 mg plus delapril 30 mg o.d. for 8 weeks. A 24-h ambulatory blood pressure monitoring recording was performed at the end of the placebo washout, of the monotherapy and of the combination therapy. Blood pressure control over the 24 h was quantified by the trough-to-peak ratio and the smoothness index. As compared to placebo, the fixed combination of manidipine and delapril produced a statistically significant (p<0.01) decrease in sitting clinic (18 +/- 9/14 +/- 5 mmHg) and 24-h blood pressure (12 +/- 7/10 +/- 5 mmHg) without affecting heart rate. This reduction was greater than that observed with single components. At the end of the 8-week combination treatment period, the rate of normalilized patients was 73%. Treatment with the fixed combination was associated with a positively high smoothness index (1.2 +/- 0.7/13.8 +/- 0.8) and with a relatively good trough-to-peak ratio (0.46/0.60). The combination of manidipine and delapril produced significant and smooth reductions in blood pressure values, which persisted over the 24-h dosing interval. These results support the use of fixed manidipine-delapril combination in the treatment of mild to moderate hypertensive patients inadequately controlled by monotherapy.

Calcium channel blocker class heterogeneity: select aspects of pharmacokinetics and pharmacodynamics

Calcium channel blockers (CCBs) comprise a heterogeneous group of compounds with unique structures and pharmacologic characteristics. These agents are employed in the treatment of hypertension, coronary ischemia, and/or supraventricular arrhythmias. CCBs are both substrates for, and in the instance of verapamil and diltiazem inhibitors of, cytochrome P450 3A4. In the case of verapamil and diltiazem, this inhibitory effect increases the likelihood of drug-drug interactions with other compounds similarly metabolized by cytochrome P450 3A4. Much of the debate with reference to a cardiovascular risk for CCBs has been quieted with the advent of sustained-release delivery systems that offer a more gradual rate of drug delivery. The most common side effects with CCBs are vasodilatory in nature and include peripheral edema, flushing, and headache. Despite the potential for side effects with CCBs, their potent blood pressure-lowering effect makes them a prerequisite for blood pressure control in many patients.

Calcium channel blockers and the kidney

Although end-stage renal disease (ESRD) currently affects only a small percentage (<0.2%) of the US population, its precursor, the mild and moderate forms of chronic kidney disease (CKD), affects 11% of the population, with significant growth in both ESRD and CKD anticipated in the rapidly aging US population. The primary diagnoses in the majority of ESRD patients are diabetes and hypertension. Results of clinical studies demonstrate that the level of proteinuria and sympathetic activation contribute to the progression of CKD to ESRD. There are sufficient clinical data to demonstrate that the dihydropyridine calcium channel blocker (DHP CCB) class of antihypertensives such as amlodipine and nifedipine, although effective in reducing systemic hypertension, lack activity in reducing proteinuria or attenuating sympathetic activity. Experimental studies and a limited number of clinical studies suggest that non-DHP CCBs, including verapamil and diltiazem, have a mechanism of action that differs from DHP CCBs. Non-DHP CCBs could potentially attenuate sympathetic activity and reduce protein excretion in patients with CKD.

Calcium-channel blockers and end-stage renal disease: pharmacokinetic and pharmacodynamic considerations

PURPOSE OF REVIEW

To characterize the pharmacokinetics and pharmacodynamics of the different calcium-channel blockers.

RECENT FINDINGS

Calcium-channel blockers have been in use for some time in the end-stage renal disease population. Their primary use has been as antihypertensive and antianginal therapies. In this regard, they are effective agents. Recently, it has been noted that dialysis-related hypotension occurs less frequently in calcium-channel blocker treated patients. Also, access patency and overall patient survival are improved with calcium-channel blocker therapy.

SUMMARY

Calcium-channel blockers are useful agents for the control of hypertension in end-stage renal disease patients and appear to favorably influence survival in this population. Calcium-channel blockers are not dialyzable and their pharmacokinetics do not substantially change with renal failure therefore they do not require dose adjustment based on level of renal function. Too few studies exist to determine if individual calcium-channel blockers differ in their effects. Prospective, randomized, controlled clinical trials are needed in the end-stage renal disease population to better understand the role of calcium-channel blockers in the excess cardiovascular disease burden of this population.