Calcium channel blockade in combination with angiotensin-converting enzyme inhibition or angiotensin II (AT(1)-receptor) antagonism in hypertensive diabetics and patients with renal disease and hypertension

Diagnostic and therapeutic problems of isolated systolic hypertension

Prevalence of isolated systolic hypertension increases with age, due to progressive elevation of SBP, and is a major risk factor for cardiovascular morbidity and mortality. Extensive research has shown that lowering SBP improves cardiovascular outcomes in patients with isolated systolic hypertension, yet SBP control rates remain largely inadequate regardless of antihypertensive treatment. Arterial stiffness is a major determinant of elevated SBP resulting from structural changes in the vascular system, mediated by neurohormonal alterations that occur with vascular ageing. Clinical data have demonstrated an independent association between arterial stiffness and cardiovascular outcomes. Therefore, arterial stiffness has the potential to be an important therapeutic target in the management of isolated systolic hypertension. Current antihypertensive treatments have limited effects on arterial stiffness, so the development of new treatments addressing neurohormonal alterations central to vascular ageing is important. Such therapies may represent effective strategies in the future management of SBP.

Synthesis of Novel 1,4- Dihydropyridine Derivatives Bearing Biphenyl-2'-Tetrazole Substitution as Potential Dual Angiotensin II Receptors and Calcium Channel Blockers

INTRODUCTION

We report the synthesis of novel 1,4-dihydropyridine derivatives containing biphenyl-2'-tetrazole moieties. We hypothesized that merging the key structural elements present in an AT1 receptor antagonist with key structural elements in 1,4-dihydropyridine calcium channel blockers would yield novel analogs with potential dual activity for both receptors. This strategy led to the design and synthesis of dialkyl 1,4-dihydro-2,6-dimethyl-4-[2-n-alkyl-1-[2΄-(1H-tetrazole-5-yl) biphenyl -4-yl] methyl] imidazole-4(or 5)-yl]- 3, 5-pyridinedicarboxylate analogs.

METHODS

These compounds were obtained by two methods starting from biphenyltetrazolyl-4-(or 5)-imidazolecarboxaldehyde intermediates employing in classical Hantzsch condensation reaction. In the first method, triphenylmethyl protecting group of 4- or 5-carboxaldehyde intermediate was first removed in acidic media and then classical Hantzsch reaction was employed in order to obtain the final products. In the second method, without further deprotection process, protected 4- or 5-carboxaldehyde intermediate directly was used in Hantzsch reaction.

RESULTS

The second method was more efficient than the first method since the deprotection and ring closure reaction occurs simultaneously in one pot.

CONCLUSION

Eight novel dihydropridines analogs were synthesized using classic Hantzsch condensation reaction. Chemical structures of the compounds were characterized by (1)H NMR, infrared and mass spectroscopy.

Influence of T-calcium channel blocker treatment on deterioration of renal function in chronic kidney disease

Some calcium channel blockers (CCBs) have renoprotective effects. Our aim was to compare the effects of different subclasses of CCBs on the deterioration of renal function in chronic kidney disease (CKD). This is a prospective, observational cohort study in a single center. The subjects were 107 nondiabetic CKD patients. The rate of deterioration of estimated glomerular filtration rate (DeltaeGFR) was calculated by [last visit eGFR - baseline eGFR/follow-up duration]. Multivariate analysis was performed using the change in urinary protein (DeltaUP) and DeltaeGFR during follow-up as response variables. CCB subclasses were L-type in 76 patients, T- and L-type in 28 patients, and nondihydropyridines in 6 patients. Multiregression analysis indicated that higher baseline proteinuria (UP) and the use of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II receptor blockers were associated with the decrease of UP, while the use of L-type CCBs, prednisolone, and probucol was associated with the increase of UP. The use of T- and L-type CCBs, ACEIs and diuretics was associated with a good outcome in terms of DeltaeGFR, whereas chronic glomerulonephritis, polycystic kidney disease, and higher baseline eGFR and UP were associated with a poor outcome. It is suggested that the use of T- and L-type CCB among other subclasses may improve the outcome of patients with nondiabetic CKD in terms of renal function.

Antihypertensive efficacy of olmesartan medoxomil or valsartan in combination with amlodipine: a review of factorial-design studies

BACKGROUND

Most patients with hypertension require more than one drug to attain recommended blood pressure (BP) targets. Initiating therapy with two agents is recommended for patients at high risk of a cardiovascular event or with a BP > 20/10 mmHg above goal. Combination therapy is effective when comprised of agents with complementary mechanisms of action, such as calcium channel blockers (CCBs) and angiotensin II-receptor blockers (ARBs). Two fixed-dose CCB/ARB combinations are approved in the US: amlodipine/valsartan (AML/VAL) and amlodipine/olmesartan medoxomil (AML/OM).

OBJECTIVES

To review and describe the efficacy of AML/VAL and AML/OM combinations by discussing similarly designed clinical trials.

METHODS

Three 8-week, randomized, double-blind, placebo-controlled, parallel-group factorial-design studies were examined (two AML/VAL; one AML/OM). The study endpoints presented in this review were: change from baseline in least-squares mean seated diastolic BP (SeDBP) and least-squares mean seated systolic BP (SeSBP). In addition to the efficacies of AML/VAL and AML/OM combinations, the efficacies of AML, VAL and OM administered as monotherapy are presented. Placebo-subtracted BP reductions were calculated for this review.

RESULTS

Patient demographics were similar but mean baseline SeBP was higher in the OM study (163.8/101.6 mmHg) than in the VAL studies (152.8/99.3 and 156.7/99.1 mmHg), possibly suggesting that the OM study included a more difficult-to-treat patient population. AML/ARB combinations consistently produced greater mean SeBP reductions than monotherapy. Least squares (LS) mean SeDBP reductions were 19.4 mmHg (AML/OM 10/40 mg; placebo-corrected: 15.9 mmHg) and 18.6 mmHg (AML/VAL 10/320 mg; placebo-corrected: 9.8 mmHg). LS mean SeSBP reductions were 28.5 mmHg (AML/OM 10/40 mg; placebo-corrected: 25.7 mmHg) and 28.4 mmHg (AML/VAL 10/320 mg; placebo-corrected: 15.5 mmHg).

CONCLUSIONS

This review of published factorial-design studies showed that the maximal marketed doses of an amlodipine/olmesartan medoxomil combination (10/40 mg) and an amlodipine/valsartan combination (10/320 mg) produced large reductions in BP from baseline. Limitations of this review include the small number of studies analyzed and the inherent heterogeneity between patient populations. Further research is warranted to directly compare the efficacy of these combinations in a randomized, controlled trial, or additional published clinical trials are required to provide larger data sets for robust meta-analyses and to overcome heterogeneity observed within these studies.

Role of combination therapy in the treatment of hypertension: focus on valsartan plus amlodipine

Hypertension control is rare in clinical practice, particularly in high-risk patients. A large factor is therapeutic inertia deriving from poorly prescribed lifestyle changes, excess monotherapy use, and scarce on-treatment modifications. The use of drug combinations significantly improves blood pressure (BP) control; in particular, fixed combinations improve therapy without increasing daily pill intake, thereby favouring patient compliance and therapy continuation. The most widely used fixed combination is based on thiazide diuretics added to either angiotensin-converting enzyme (ACE) inhibitors or angiotensin II receptor blockers (ARBs). Several large-scale clinical trials have been conducted showing that these combinations are effective in lowering BP. However, thiazide diuretics can reduce the metabolic benefits derived from renin-angiotensin-aldosterone system (RAAS) inhibitors in high metabolic risk patients. In contrast, ACE inhibitors or ARBs combined with dihydropyridine calcium channel antagonists (DHPCAs) exert a marked antihypertensive effect without decreasing metabolic protection by RAAS blockade. In the recent JIKEI heart study, approximately 60% of patients affected by hypertension, heart failure, coronary heart disease or their combination in the valsartan arm were simultaneously treated with DHPCAs. Of note, a 39% reduction in the primary endpoint of combined morbidity and mortality was reported in the valsartan compared with the non-valsartan arm. Furthermore, in a recent multinational study, 83% of 3161 hypertensive patients treated with valsartan and the DHCPA amlodipine reported a concontrolled BP after 8 weeks of treatment. As expected, amlodipine did not negatively influence the metabolic profile of patients, thereby supporting the role of ARB+DHPCA combinations as effective and promising tools in hypertension treatment. In summary, the combination of ARBs with DHPCAs is an effective strategy in hypertension treatment through synergy between their antihypertensive and vascular protective actions, persistent metabolic benefits deriving from RAAS inhibition, and reduced incidence of side effects.

Metabolic syndrome, new onset diabetes, and new end points in cardiovascular trials

Metabolic syndrome affects approximately 44% of the US population over the age of 50 years. Although conflicting definitions exist, the syndrome is typically characterized by abdominal obesity, dyslipidemia, hypertension, and insulin resistance. Thus, it is a major risk factor for both coronary heart disease and type 2 diabetes. Furthermore, the risk of cardiovascular (CV) death is significantly increased in patients with diabetes and/or the metabolic syndrome. Although very few studies exist in patients with the metabolic syndrome, lifestyle changes and drug intervention targeted at the individual components have been shown to reduce the risk of developing diabetes and the incidence of CV disease in high-risk patients. Because many of the conventional antihypertensive drugs may affect the development of new onset diabetes, both positively and negatively, the choice of therapy is particularly important in this population. However, the long-term clinical trials to date have either not included new onset diabetes as a protocol end point or used various different criteria, making comparisons difficult. This review assesses the need for future research into metabolic syndrome and discusses whether clinical surrogates for CV end points, such as new onset diabetes, should be included in clinical trials of new drugs, new regimens, or new indications.