Current status of calcium channel blockers in patients with cardiovascular disease

Role of Calcium Channel Blockers in Myocardial Preconditioning

Coronary heart disease is the leading cause of mortality and morbidity worldwide. The effects of coronary heart disease are usually attributable to the detrimental effects of acute myocardial ischaemia-reperfusion injury. Newer strategies such as ischaemic or pharmacological preconditioning have been shown to condition the myocardium to ischaemia-reperfusion injury and thus reduce the final infarct size. This review investigates the role of calcium channel blockers in myocardial preconditioning. Additionally, special attention is given to nicorandil whose mechanism of action may be associated with the cardioprotective effects of preconditioning. There are still many uncertainties in understanding the role of these agents in preconditioning, but future research in this direction will certainly help reduce coronary heart disease.

Lercanidipine in the treatment of hypertension

OBJECTIVE

To review the literature regarding the efficacy, tolerability, and utility of lercanidipine in the treatment of hypertension.

DATA SOURCES

A search of the literature was performed using MEDLINE (1966-September 2006), EMBASE Drugs and Pharmacology (1980-September 2006), and Current Contents/Clinical Medicine (week 24, 2005-week 30, 2006). Package inserts from lercanidipine, nifedipine, felodipine, and amlodipine were also reviewed for comparison of adverse effects.

STUDY SELECTION AND DATA EXTRACTION

Articles were limited to clinical trials, abstracts, and review articles published in English.

DATA SYNTHESIS

Lercanidipine is a novel dihydropyridine (DHP) calcium-channel blocker indicated for the treatment of mild-to-moderate hypertension. Although it is not yet available in the US, lercanidipine has been utilized extensively in other countries. In 2 randomized controlled trials of approximately 400 patients with mild-to-moderate hypertension, lercanidipine showed efficacy similar to that of 2 other DHPs, felodipine and slow-release nifedipine, in significantly reducing systolic blood pressure and diastolic blood pressure (DBP) after 4 weeks. In a longer trial (12 mo), lercanidipine 10 mg/day led to normalized blood pressure in 49% of patients after 4 weeks. A postmarketing trial of 9050 patients corroborated the results observed in previous clinical trials, with 64% of patients achieving a DBP of less than 90 mm Hg and 32% attaining blood pressure control (<140/90 mm Hg). In elderly patients, lercanidipine was found comparable with lacidipine and nifedipine, showing similar decreases in DBP when compared with nifedipine (-18.3 vs -17.7 mm Hg, respectively). What distinguishes lercanidipine from other members of the DHP class is its lower incidence of adverse effects, particularly edema. One study showed that fewer patients withdrew secondary to adverse drug reactions in the lercanidipine (0.9%) and nifedipine (3.8%) group compared with the felodipine (4.5%) group. Lercanidipine has also shown efficacy similar to that of other antihypertensives, including atenolol, captopril, and losartan.

CONCLUSIONS

Lercanidipine may be an option in the treatment of hypertension, as current literature suggests comparable antihypertensive efficacy and better tolerability. Further randomized, double-blind clinical trials must be conducted in order to clarify its position among other antihypertensive medications.

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.

l-carnosine and verapamil inhibit hypoxia-induced expression of hypoxia inducible factor (HIF-1 alpha) in H9c2 cardiomyoblasts

Contractile failure of myocardial cells is a common cause of mortality in ischemic heart disease. In response to hypoxic conditions, cells upregulate the activity of hypoxia-inducible factor 1 (HIF-1) and express a number of genes encoding proteins that either enhance O (2)delivery or increase cellular ATP levels. HIF-1 is a heterodimer of bHLH-PAS proteins, HIF-1 alpha and HIF-1 beta. Both subunits are constitutively expressed under normoxic conditions, but HIF-1 alpha levels are kept low by proteolytic degradation, then stabilized under conditions of low O (2)by a mechanism that is poorly understood. Here we tested the hypothesis that expression of HIF-1 alpha in cardiac cells may be affected by two known cardioprotective agents. We tested l-carnosine, a naturally occurring dipeptide which has been shown to improve myocardial contractility during hypoxia, and verapamil, a calcium channel blocker frequently prescribed for the treatment of heart disease. The levels of HIF-1 alphamRNA remained relatively stable during time course hypoxia (1% O (2)) in H9c2 cardiomyoblasts, then increased slightly after 24 h. In cells pretreated with 1 microM carnosine, the levels of mRNA were transiently reduced, but then increased after 24 h similar to the controls. The levels of HIF-1 alpha protein increased rapidly in H9c2 cells within 30 min of hypoxia, but this induction was significantly reduced in cells treated with either carnosine or verapamil. In addition, treatment of cells with these agents further reduced the low levels of HIF-1 under normoxic conditions. These results suggest that l-carnosine and verapamil may affect the regulated proteolytic degradation of HIF-1 alpha in heart cells during hypoxia.