Current Vascular Pharmacology - Volume 9, Issue 4, 2011

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Aims: Treatment with statins has significantly reduced cardiovascular morbidity and mortality, an effect attributed to both the low-density lipoprotein cholesterol (LDL-C) lowering capacity and the pleiotropic actions of these drugs. However, residual risk remains even after intense LDL-C lowering. Therefore, additional treatment with lipid-lowering drugs which improve other lipid parameters and have favourable non-lipid effects may be of clinical value. The aim of the present article is to review the actions of nicotinic acid and comment on the limitations and possible benefits of this drug in clinical practice. Methods: Relevant articles were identified through a Pubmed search up to July 2010. Results: Nicotinic acid (niacin) improves the lipid profile and has been associated with reduction in morbidity and mortality from cardiovascular disease. This favourable outcome may be due to several beneficial actions of this drug, such as antithrombotic, anti-inflammatory and antioxidant. However, its use has been limited due to side effects, especially flushing. A novel formulation with a prostaglandin D2 receptor antagonist (laropiprant) appears to substantially decrease the frequency and intensity of flushing, without affecting the other properties of niacin. Some concerns regarding treatment with nicotinic acid include impaired glucose metabolism and elevations in uric acid and homocysteine levels. Conclusion: Nicotinic acid is a safe supplementary (to statins) lipid lowering agent which may also improve cardiovascular outcomes. Whether its combination with laropiprant will be proved equally effective and more favourable in terms of adverse effects remains to be established by large clinical trials.

Obesity is a highly prevalent complex trait that raises the risk of other chronic diseases such as type 2 diabetes, certain cancers, sleep apnea, and cardiovascular disease, and shortens lifespan. Clinical intervention studies focused on weight loss and epidemiological studies of obesity indicate that genetic variation may modify the relationship between lifestyle behaviors and weight loss or weight gain. Similar observations have also emerged from pharmacogenetic studies. The literature includes several reports from these studies, but few examples of interactions have been adequately replicated. In this review we introduce the topics of population genetics and gene x environment interaction research. We also provide a systematic review of the published literature on gene x lifestyle (physical activity and dietary factors) and gene x drug interactions in relation to obesity. Finally, we overview the scope and findings from these studies and discuss some of their strengths and limitations.

Over the past decade different effective treatment options for use in pulmonary arterial hypertension (PAH) have been developed. Due to multiple pathophysiological pathways in PAH and unsatisfactory overall results with the use of monotherapy in a substantial number of PAH patients, there is a pharmacological rationale for combination therapy. The currently approved substances target the prostacyclin, the endothelin and the NO (nitric oxide) -pathways. Those agents have shown a varying degree of improvement in different categories of PAH associated limitations like hemodynamics, exercise capacity, functional class, and quality of life. However, clinical worsening over time is still significant in most patients irrespective of the treatment utilized. The recently published ESC-ERS (European Society of Cardiology and European Respiratory Society) guidelines on pulmonary hypertension suggest the use of combination therapy in patients who do not respond adequately to monotheapy. This article reviews and critically discusses the available data on combination therapy in PAH.

Atherosclerotic renal artery stenosis (ARAS) is a progressive disease and it is usually associated with hypertension as well as with chronic kidney and cardiovascular disease. Although the anatomical lesions are relatively easy to depict, there is need to identify diagnostic methods to establish the functional significance of the stenosis and predict the response to revascularization. Over the last years, renal revascularization appears to be increasingly performed in patients with ARAS. However, controversy abounds as so far prospective, randomised trials did not document any benefit of revascularization with or without stenting plus optimal medical treatment over optimal medical treatment alone. In this review, we discuss the current data in the field of diagnosis and management of patients with ARAS

Abdominal aortic aneurysm (AAA) is a common disease and a major cause of death through rupture, the risk of which increases with aneurysm size. There is approximately a 5 year interval from when aneurysmal dilatation develops until it reaches a size where surgery is indicated. Slowing, or arresting, aneurysm growth during this period would be beneficial. Aneurysmal aortic wall degeneration is a multifactorial, chronic inflammatory process resulting via activation of matrix metalloproteinases (MMPs), in destruction of mural connective tissue. Doxycycline, a tetracycline antibiotic, is a known inhibitor of MMPs. Animal studies of doxcycline for AAA provide significant evidence of a beneficial effect. However, the human studies, comprising 6 controlled trials and 2 cohort studies, provide conflicting evidence. They are generally of poor methodological quality with small numbers (just 255 subjects analyzed), lack of adjustment for confounding variables, short term doxycycline exposure and a lack of long term follow up. Standardization of dose (per unit weight) and confirmation of compliance remain other systemic failings. The safety of long-term doxycycline use is yet to be proved. The evidence for any beneficial effect of doxycycline as a treatment for AAA, therefore, remains weak. Further studies are required and will ideally be multicentre, involve large subject numbers and be of high quality randomization and blinding with longer periods of doxycycline exposure, confirmation of compliance, standardization of confounding variables and prolonged follow up.

Platelets play a crucial role in thrombosis, inflammation, immunity and atherogenesis. Antiplatelet agents are widely used in patients with acute coronary syndrome and other cardiovascular disorders. Aspirin and clopidogrel are the most commonly prescribed antiplatelet agents, with a relatively safe profile and efficiency in a variety of clinical conditions. Numerous prospective studies have revealed variability of antiplatelet efficacy. The so called “antiplatelet resistance” prompted a search for mechanisms implicated in poor responsiveness to aspirin and clopidogrel therapy. In this regard, genetic polymorphisms in the platelet receptor genes attracted considerable interest. Specific genetic variants in platelet receptors such as the P2Y12, glycoprotein (GP) IIb/IIIa, GPIa/IIa, GPIb/IX/V and the cytochrome P450 (CYP) family of genes are associated with variable response to antiplatelet therapy and cardiovascular events. Genetic polymorphisms and haplotypes that comprehensively capture the genetic information encoded within the platelet receptor genes can, to some extent, predict response to the antiplatelet drug better than any single genotype. Genotyping for multiple receptor variants in patients on antiplatelet therapy, complemented by standardized quantification of platelet function, can provide useful information for future drug design studies and possibly for personalized antiplatelet therapy and prevention of thrombotic events. Additional information is, however, needed to evaluate the cost-effectiveness of complex genetic and platelet function testing.

Microparticles are circulating fragments derived from blebbing and shedding of cell membranes through several mechanisms that include activation, apoptosis and cell damage. In the past they were largely considered as unimportant cell “dust”, but more refined detection techniques have revealed large variations in their relative proportion and concentration in numerous disease states. Importantly, these conditions include the most prevalent causes of death and disability in our societies, namely cardiovascular, neoplastic, and inflammatory diseases. Microparticles carry procoagulant, proapoptotic and neoangiogenetic materials in the blood stream, and can also be viewed as a technique cells may adopt to rapidly modify their phenotype, independently from genetic signals. In this review, we focus on the role of these very small (<1 micron) particles, not only as mere markers of an underlying pathologic state, but also as primordial intercellular messengers and defense mechanism that every viable cell can exploit in distress conditions. In this view, we suggest that this old communication system could be the target of future high-tech interventions, with potential broad consequences.

Nowadays, the great saphenous vein is the vascular conduit that is most frequently employed in coronary and peripheral revascularization surgery. It is known that saphenous vein bypass grafts have shorter patency than arterial ones, partly because the wall of the normal saphenous vein has different structural and functional characteristics. The features of this vein can be affected by the large distention pressures it is submitted to during its preparation and insertion into the arterial system. Indeed, a vein graft is subjected to considerable changes in hemodynamic forces upon implantation into the arterial circulation, since it is transplanted from a non-pulsatile, low-pressure, low-flow environment with minimal shear stress to a highpressure system with pulsatile flow, where it undergoes cyclic strain and elevated shear. These changes can be responsible for functional and morphological alterations in the vessel wall, culminating in intima hyperproliferation and atherosclerotic degeneration, which contribute to early graft thrombosis. This review has followed a predetermined strategy for updating information on the human saphenous vein (HSV). Besides presenting the aspects relative to the basic pharmacology, this text also includes surgical aspects concerning HSV harvesting, the possible effects of the major groups of cardiovascular drugs on the HSV, and finally the interference of major cardiovascular diseases in the vascular reactivity of the HSV.

Nicotinic acid is the oldest hypolipidemic agent in use, since 1955. It possesses broad-spectrum lipidmodifying properties including reduction of total cholesterol, low density lipoprotein (LDL) cholesterol and triglycerides. In addition, nicotinic acid is the most potent available hypolipidemic agent for increasing plasma high density lipoprotein (HDL) cholesterol and decreasing lipoprotein (a) levels. Clinical trials have demonstrated that nicotinic acid can decrease cardiovascular morbidity and mortality. However, nicotinic acid is underused in the clinical setting due to its high rate of side effects, including flushing, gastrointestinal disorders, rash, hyperglycemia and hyperuricemia. The nicotinic acid-associated side effects and their management are the focus of this review.