Protective action of a calcium antagonist, nilvadipine, against aortic calcium deposition--a pathogenic factor in atherosclerosis

Nilvadipine. A review of its pharmacodynamic and pharmacokinetic properties, therapeutic use in hypertension and potential in cerebrovascular disease and angina

Nilvadipine, a calcium antagonist of the dihydropyridine class, selectively blocks calcium channels in vascular smooth muscle. Compared with nifedipine, the prototype of the dihydropyridines, nilvadipine has a longer duration of action. The antihypertensive efficacy of nilvadipine appears to be comparable with that of nicardipine and nitrendipine, enalapril and captopril and hydrochlorothiazide/triamterene, although further clinical experience is required to establish the claimed advantages nilvadipine may have over the other dihydropyridine derivatives currently used to treat hypertension. Preliminary studies suggest that nilvadipine may also be useful in the treatment of patients with stable exertional or variant angina. Studies conducted in Japan indicate that nilvadipine improves symptoms resulting from cerebral infarction in some patients, but further comparative studies are required to confirm these results. The tolerability of nilvadipine appears to be comparable with that of nicardipine and better than that of nifedipine with respect to flushes, oedema and liver function abnormalities. As is typical of calcium antagonists, there is no evidence of tolerance to the antihypertensive effects of nilvadipine. The drug is equally effective in treating hypertension in elderly and younger patients and does not appear to adversely affect glucose or lipid metabolism. Thus, provided its apparently good tolerability is confirmed by wider clinical experience, it should be a suitable alternative to other calcium antagonists when used alone or in conjunction with other drugs for the majority of patients with mild to moderate hypertension.

Comparable beneficial effects of defibrotide and nifedipine in calcium induced atherosclerosis

The present study demonstrates the antiatherosclerotic property of Defibrotide (DFT) in an experimental model in which the pathology is secondary to calcium deposition in the vessel wall and various organs. Rats were treated by gavage for 21 consecutive days with Vitamin D3 and/or, twice a day, with DFT or Nifedipine (N). The calcium contents of aorta, heart and kidney were determined by atomic absorption spectrometry. Specimens of these tissues were examined histologically. DFT or N administered alone did not modify the calcium contents of aorta, heart or kidney. On the contrary, Vitamin D3 caused a huge increase in the calcium concentration in the aorta and in the kidney, whereas the heart content was only double that of control animals. In rats treated with Vitamin D3, contemporaneous administration of DFT or N sharply and highly significantly reduced the aorta calcium concentration and there were less striking, although still significant, reductions in the other two tissues. Histological examination paralleled these data; the effect of DFT or N in reducing the mineralization of aorta and heart was very evident, and more pronounced for DFT. These results confirm that DFT, even though not belonging to the class of the calcium antagonists, has comparable antiatherosclerotic properties, possibly due to its endothelial protective efficacy, as evidenced by the lesser amount of calcium in the aortic tissue.

Effects of doxazosin on atherosclerosis in cholesterol-fed rabbits

Doxazosin was administered to rabbits fed diets enriched in cholesterol and peanut oil for 7.5 or 12 weeks, in 2 separate experiments. Doxazosin suppressed the accumulation of cholesterol and formation of atherosclerotic plaques in the aortas of treated rabbits and prevented a diet-induced increase in aortic collagen and wall mass. Doxazosin was more effective in the thoracic and abdominal segments of the aorta than in the aortic arch. Pharmacokinetic analysis indicated that treated rabbits were exposed to concentrations of doxazosin, integrated over 24 h, which were consistent with the therapeutic range of doxazosin measured in patients treated for hypertension. Doxazosin did not alter serum levels of cholesterol or triglycerides, nor were there any consistent effects on glucose, free fatty acid or ketone levels. Hypotheses of the mechanism of action of doxazosin are discussed, including the possible involvement of alpha 1-adrenergic receptors in recruitment of smooth muscle cells by subintimal macrophages and nonadrenergic mechanisms of inhibition of lipid infiltration.

Hypothesis: etiology of atherosclerosis and osteoporosis: are imbalances in the calciferol endocrine system implicated?

Atherosclerosis and osteoporosis are currently considered unrelated diseases. Osteoporosis involves bone calcium (Ca) loss and predominantly affects females after menopause. Atherosclerosis is an illness predominantly affecting males, and is primarily characterized by abnormal lipid metabolism. However, pathological calcification of the arterial wall is an underlying feature of atherosclerosis. Ca homeostasis is thus important in atherosclerosis as well as in osteoporosis. Men also develop osteoporosis although at a later age than women, and, as osteoporosis progresses in women, there is an accompanying calcification of arteries leading to increased incidence of atherosclerosis in aging women. Thus, during old age, both atherosclerosis and osteoporosis are prevalent in both males and females. The dramatic increase in atherosclerosis among women as they develop osteoporosis suggests that the two illnesses may be more closely related than previously realized. The use of vitamin D as a food supplement coincides with epidemic onsets of atherosclerosis and osteoporosis, and excess vitamin D induces both conditions in humans and laboratory animals. These observations suggest a role for chronic vitamin D excess in the etiology of the two illnesses. Magnesium (Mg) deficiency, nicotine, and high dietary cholesterol are contributing factors that accentuate adverse effects of vitamin D.

A new generation of calcium antagonists and their role in atherosclerosis

A new generation of calcium antagonists is being developed in an attempt to improve the already widespread therapeutic applications of this class of drugs. In this report the effect of these new calcium antagonists on those processes involved in atherogenesis that occur in the cellular component of the arterial wall is reviewed. The new generation of calcium antagonists appears to possess many of the antiatherosclerotic properties demonstrated by their prototypes. Moreover, these new compounds may have unique mechanisms of action and may be more potent than their first-generation counterparts.