Calcium channel blockers and progression of coronary artery disease

Isradipine lowers human arterial low density lipoprotein retention in vivo

During the recent past it has been discussed that calcium antagonists may exert antiatherosclerotic actions at the vessel wall. Apolipoprotein B containing lipoproteins were isolated by immunoaffinity chromatography and radiolabeled with 123-iodine. The effect of 2 x 2.5 mg isradipine on the low density lipoproteins (LDL) entry into the carotid and femoral arteries of 12 hypertensive patients with primary hyperlipoproteinemia (total cholesterol >6.5 mmol/l [250 mg/dL) was examined. Cholesterol -1.7% (P< 0.05 664), high density lipoprotein (HDL) cholesterol +4.5% (P< 0.01 123), and LDL cholesterol -1% (P< 0.01 563) did not change, nor did any of the safety parameters. The types of entry kinetics reflecting vascular surface lining did not change while the LDL retention 20 h after tracer application was depressed by up to 23.5%. The data were comparable in the carotid and femoral artery segments, the significance level ranging up to 0.0009. These results indicate a decreased LDL retention in the arterial wall of hypertensive patients induced by isradipine. The clinical implications of the findings ought to be pursued in properly designed clinical trials.

A study to determine the response of coronary atherosclerosis to raising low high density lipoprotein cholesterol with a fibric-acid derivative in men after coronary bypass surgery. The rationale, design, and baseline characteristics of the LOCAT Study. Lopid Coronary Angiography Trial

Several clinical trials have shown that reducing serum cholesterol levels retards the progression of coronary atherosclerosis assessed by serial angiography. By contrast, as yet no studies have addressed the impact of increasing high density lipoprotein (HDL) cholesterol levels on progression of coronary artery disease (CAD). As HDL cholesterol is inversely related to the risk of CAD, we hypothesize that an intervention that raises low HDL cholesterol concentrations may have a beneficial effect on the course of CAD. Lopid Coronary Angiography Trial (LOCAT) was designed to test this hypothesis. Three hundred and ninety-five men, aged < or = 70 years, all of whom had previously undergone coronary bypass surgery, were randomly assigned to receive either slow-release gemfibrozil, 1200 mg once daily, or a matching placebo for on average 2 1/2 years. The lipid inclusion criteria were HDL cholesterol concentration < or = 1.1 mmol/L, low density lipoprotein (LDL) cholesterol < or = 4.5 mmol/L, and serum triglyceride < or = 4.0 mmol/L. Subjects were not accepted if they had manifest diabetes, body mass index > 30 kg/m2, uncontrolled hypertension, or if they were regular smokers. All randomized subjects underwent baseline coronary angiography, which will be repeated at the end of the study. The angiograms will be analyzed using the Cardiovascular Measurement System, a validated computer-assisted image-analysis and quantitation package. The primary endpoints are the changes in the per-patient mean of 1) the average diameter of evaluable native coronary segments, and 2) the minimal luminal diameter of evaluable stenoses, and 3) the appearance of new lesions. Extensive lipoprotein and other metabolic studies and analyses of genetic polymorphisms are carried out to study the determinants of CAD progression. At baseline, the study subjects were 59.1 +/- 6.8 (mean +/- standard deviation) years old, had a body mass index 26.4 +/- 2.2 kg/m2, and serum triglyceride, serum cholesterol, HDL cholesterol, and LDL cholesterol concentrations 1.64 +/- 0.64, 5.17 +/- 0.64, 0.82 +/- 0.14, and 3.61 +/- 0.53 mmol/L, respectively.

New avenues in antihypertensive drug treatment

After a brief synopsis of the classical antihypertensive drugs a survey is given of the newer therapeutics, such as calcium antagonists, ACE-inhibitors and alpha 1-adrenoceptor antagonists. Experimental drugs, such as imidazoline receptor agonists, renin inhibitors, angiotensin II receptor antagonists, alpha 2-adrenoceptor antagonists, potassium channel openers, ketanserin, endopeptidase inhibitors, and hybrid (multifactorial) drugs are discussed, with special attention for their modes of action. In spite of the ever increasing number of antihypertensive drugs and principles, the large scale of clinical evidence for a beneficial effect of long-term treatment (in particular with respect to protection against stroke) remains limited to diuretics and beta-blockers. In spite of this limitation it seems worthwhile to consider the newer antihypertensive drugs as well, especially for optimal treatment of the individual patient. The newer drugs may in particular offer special advantages in the presence of concomitant diseases, such as diabetes mellitus, hyperlipidaemia, angina pectoris or congestive heart failure.

Felodipine: a new dihydropyridine calcium-channel antagonist

Felodipine, a dihydropyridine calcium-channel antagonist, significantly reduces systolic and diastolic blood pressure (BP) in patients with hypertension and has been associated with beneficial hemodynamic effects in patients with chronic stable angina pectoris or congestive heart failure (CHF). In hypertensive patients, felodipine does not appear to significantly affect glomerular filtration rate, creatinine clearance, glucose tolerance, or plasma lipoprotein concentrations. Studies comparing felodipine with other agents as monotherapy in mild to moderate hypertension have demonstrated felodipine to be at least as efficacious as hydrochlorothiazide (HCTZ) and HCTZ plus amiloride hydrochloride in combination. Comparisons of felodipine with other agents as adjuncts to beta-blocker or diuretic therapy have shown felodipine to be at least as effective as HCTZ, propranolol hydrochloride, prazosin hydrochloride, and nifedipine. Evaluations of patients with chronic stable angina are limited, and additional studies are needed before felodipine can be recommended for the routine management of angina pectoris. Similarly, additional studies are essential to delineate the role of felodipine, if any, in the management of CHF. In the management of hypertension, felodipine 5-40 mg/d significantly reduces systolic and diastolic BP. Although some patients may be controlled throughout the entire dosing interval when felodipine is administered bid, many patients will require more frequent dosing to obtain adequate BP control. Adverse effects associated with felodipine are similar to those of other dihydropyridine calcium-channel antagonists and include peripheral edema, headache, dizziness, flushing, and fatigue. A potentially clinically important drug interaction was observed when felodipine was administered concomitantly with theophylline aminopropanol; significant decreases in theophylline concentrations were noted. In summary, felodipine appears to be safe and effective for the management of hypertension when used alone or in combination with other antihypertensive agents. The efficacy of felodipine in the management of chronic stable angina pectoris and CHF requires further investigation.