Effect of niacin and atorvastatin on lipoprotein subclasses in patients with atherogenic dyslipidemia

Lipid-lowering treatment and low-density lipoprotein cholesterol target achievement in patients with type 2 diabetes and acute coronary syndrome

BACKGROUND

Patients with type 2 diabetes mellitus characteristically display an atherogenic lipid profile with high triglyceride concentrations, low high-density lipoprotein cholesterol (HDL-C) concentrations and low-density lipoprotein cholesterol (LDL-C) concentrations not always elevated. It is unclear if patients with diabetes who present with an acute coronary syndrome (ACS) receive different or more-potent lipid-lowering therapy (LLT).

AIMS

To investigate lipid abnormalities in patients with and without type 2 diabetes hospitalised for an ACS, and use of LLT before admission and 4 months after the event.

METHODS

Patients were included in the observational DYSIS II study if they were hospitalised for an ACS and had a full lipid profile.

RESULTS

Of 3803 patients, diabetes was documented in 1344 (54.7%). Compared to patients without diabetes, those with diabetes had a lower mean LDL-C (101.2 vs. 112.0mg/dL; 2.6 vs. 2.9mmol/L; P<0.0001), with a greater proportion attaining concentrations<70mg/dL (1.8mmol/L) (23.9% vs. 16.0%; P<0.0001) and<55mg/dL (1.4mmol/L) (11.3% vs. 7.3%; P<0.0001), a higher mean triglyceride concentration (139.0 vs. 121.0mg/dL; 1.6 vs. 1.4mmol/L; P<0.0001) and a lower HDL-C concentration. LLT was more commonly given to patients with diabetes (77.5% vs. 58.8%; P<0.0001); there were no differences in types of therapy prescribed. Four months after hospitalisation, most patients from both groups were being treated with LLT (predominantly statin monotherapy).

CONCLUSIONS

Despite the different lipid profiles, the type of LLT prescribed did not vary depending on the presence or absence of type 2 diabetes. There was no difference in LLT in patients with and without diabetes at 4-month follow-up, except for fibrates, which were used in 2% of patients with and 1% of patients without diabetes. Statin monotherapy of intermediate potency was the predominant treatment in both groups.

Pharmacological Intervention to Modulate HDL: What Do We Target?

The cholesterol concentrations of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) have traditionally served as risk factors for cardiovascular disease. As such, novel therapeutic interventions aiming to raise HDL cholesterol have been tested in the clinical setting. However, most trials led to a significant increase in HDL cholesterol with no improvement in cardiovascular events. The complexity of the HDL particle, which exerts multiple physiological functions and is comprised of a number of subclasses, has raised the question as to whether there should be more focus on HDL subclass and function rather than cholesterol quantity. We review current data regarding HDL subclasses and subclass-specific functionality and highlight how current lipid modifying drugs such as statins, cholesteryl ester transfer protein inhibitors, fibrates and niacin often increase cholesterol concentrations of specific HDL subclasses. In addition this review sets out arguments suggesting that the HDL3 subclass may provide better protective effects than HDL2.

The role of HDL in plaque stabilization and regression: basic mechanisms and clinical implications

On the basis of studies that extend back to the early 1900s, regression and stabilization of atherosclerosis in humans has progressed from being a concept to one that is achievable. Successful attempts at regression generally applied robust measures to improve plasma lipoprotein profiles. Possible mechanisms responsible for lesion shrinkage include decreased retention of atherogenic apolipoprotein B within the arterial wall, efflux of cholesterol and other toxic lipids from plaques, emigration of lesional foam cells out of the arterial wall, and influx of healthy phagocytes that remove necrotic debris as well as other components of the plaque. Currently available clinical agents, however, still fail to stop most cardiovascular events. For years, HDL has been considered the 'good cholesterol.' Clinical intervention studies to causally link plasma HDL-C levels to decreased progression or to the regression of atherosclerotic plaques are relatively few because of the lack of therapeutic agents that can selectively and potently increase HDL-C. The negative results of studies that were carried out have led to uncertainty as to the role that HDL plays in atherosclerosis. It is becoming clearer, however, that HDL function rather than quantity is most crucial and, therefore, discovery of agents that enhance the quality of HDL should be the goal.

Dyslipidaemia and its treatment in patients with type 2 diabetes: A joint analysis of the German DIVE and DPV registries

AIMS

To compare lipid abnormalities in people with and without type 2 diabetes mellitus (T2DM) and to assess the effect of treatment.

MATERIALS AND METHODS

We combined data from the German DIVE (DIabetes Versorgungs-Evaluation) and DPV (Diabetes-Patienten-Verlaufsdokumentation) databases to produce a large cohort of people with T2DM. The characteristics of people receiving and not receiving lipid-modifying therapy (LMT) were compared, including demographics, cardiovascular (CV) risk factors and comorbidities. Lipid profiles were evaluated, and the achievement of recommended LDL cholesterol and non-HDL cholesterol targets was assessed. The effect on lipid levels in subgroups of patients aged ≥60 years, being obese or with CV disease was also investigated.

RESULTS

A total of 363 949 people were included in the analysis. Of these, only 97 160 (26.7%) were receiving LMT. These individuals were older than those not receiving LMT, and comorbidities were more prevalent. Statins were the most commonly used agents (84.2%), with ezetimibe, fibrates and nicotinic acid taken by a small proportion of people. The median LDL cholesterol level was lower for the LMT group (100.5 vs 114.0 mg/dL; P < .001), as was the non-HDL cholesterol level (131.0 vs 143.1 mg/dL; P < .001), while the triglyceride level was higher (160.3 vs 152.0 mg/dL; P < .001). HDL cholesterol was lower in the LMT group for both men (41.0 vs 42.0 mg/dL; P < .001) and women (47.5 vs 48.0 mg/dL; P < .001). Elderly people were more likely to have achieved the target lipid levels, while obese people were less likely. For people with CV disease, there was a greater likelihood of achieving LDL, total and non-HDL cholesterol targets, but less chance of attaining a desired HDL cholesterol level.

CONCLUSIONS

Dyslipidaemia was highly prevalent in this large population and management of lipid abnormalities was suboptimal. The distinct lipid profile of people with T2DM warrants further investigation into the use of non-statins in addition to statin LMT.

Effect of PCSK9 Inhibition by Alirocumab on Lipoprotein Particle Concentrations Determined by Nuclear Magnetic Resonance Spectroscopy

BACKGROUND

In patients with discordance between low-density lipoprotein (LDL) cholesterol and LDL particle (LDL-P) concentrations, cardiovascular risk more closely correlates with LDL-P.

METHODS AND RESULTS

We investigated the effect of alirocumab, a fully human monoclonal antibody to proprotein convertase subtilisin/kexin type 9, on lipoprotein particle concentration and size in hypercholesterolemic patients, using nuclear magnetic resonance spectroscopy. Plasma samples were collected from patients receiving alirocumab 150 mg every 2 weeks (n=26) or placebo (n=31) during a phase II, double-blind, placebo-controlled trial in patients (LDL cholesterol ≥100 mg/dL) on a stable atorvastatin dose. In this post hoc analysis, percentage change in concentrations of LDL-P, very-low-density lipoprotein particles, and high-density lipoprotein particles from baseline to week 12 was determined by nuclear magnetic resonance. Alirocumab significantly reduced mean concentrations of total LDL-P (-63.3% versus -1.0% with placebo) and large (-71.3% versus -21.8%) and small (-54.0% versus +17.8%) LDL-P subfractions and total very-low-density lipoprotein particle concentrations (-36.4% versus +33.4%; all P<0.01). Total high-density lipoprotein particles increased with alirocumab (+11.2% versus +1.4% with placebo; P<0.01). There were greater increases in large (44.6%) versus medium (17.7%) or small high-density lipoprotein particles (2.8%) with alirocumab. LDL-P size remained relatively unchanged in both groups; however, very-low-density and high-density lipoprotein particle sizes increased to a significantly greater extent with alirocumab.

CONCLUSIONS

Alirocumab significantly reduced LDL-C and LDL-P concentrations in hypercholesterolemic patients receiving stable atorvastatin therapy. These findings may be of particular relevance to patients with discordant LDL-C and LDL-P concentrations.

CLINICAL TRIAL REGISTRATION

URL: https://clinicaltrials.gov. Unique identifier: NCT01288443.

Extended-release niacin/laropiprant significantly improves lipid levels in type 2 diabetes mellitus irrespective of baseline glycemic control

Background

The degree of glycemic control in patients with type 2 diabetes mellitus (T2DM) may alter lipid levels and may alter the efficacy of lipid-modifying agents.

Objective

Evaluate the lipid-modifying efficacy of extended-release niacin/laropiprant (ERN/LRPT) in subgroups of patients with T2DM with better or poorer glycemic control.

Methods

Post hoc analysis of clinical trial data from patients with T2DM who were randomized 4:3 to double-blind ERN/LRPT or placebo (n=796), examining the lipid-modifying effects of ERN/LRPT in patients with glycosylated hemoglobin or fasting plasma glucose levels above and below median baseline levels.

Results

At Week 12 of treatment, ERN/LRPT significantly improved low-density lipoprotein cholesterol, high-density lipoprotein cholesterol (HDL-C), non-high-density lipoprotein cholesterol, triglycerides, and lipoprotein (a), compared with placebo, with equal efficacy in patients above or below median baseline glycemic control. Compared with placebo, over 36 weeks of treatment more patients treated with ERN/LRPT had worsening of their diabetes and required intensification of antihyperglycemic medication, irrespective of baseline glycemic control. Incidences of other adverse experiences were generally low in all treatment groups.

Conclusion

The lipid-modifying effects of ERN/LRPT are independent of the degree of baseline glycemic control in patients with T2DM (NCT00485758).

Effects of lipid-lowering drugs on high-density lipoprotein subclasses in healthy men-a randomized trial

CONTEXT AND OBJECTIVE

Investigating the effects of lipid-lowering drugs on HDL subclasses has shown ambiguous results. This study assessed the effects of ezetimibe, simvastatin, and their combination on HDL subclass distribution.

DESIGN AND PARTICIPANTS

A single-center randomized parallel 3-group open-label study was performed in 72 healthy men free of cardiovascular disease with a baseline LDL-cholesterol of 111±30 mg/dl (2.9±0.8 mmol/l) and a baseline HDL-cholesterol of 64±15 mg/dl (1.7±0.4 mmol/l). They were treated with ezetimibe (10 mg/day, n = 24), simvastatin (40 mg/day, n = 24) or their combination (n = 24) for 14 days. Blood was drawn before and after the treatment period. HDL subclasses were determined using polyacrylamide gel-tube electrophoresis. Multivariate regression models were used to determine the influence of treatment and covariates on changes in HDL subclass composition.

RESULTS

Baseline HDL subclasses consisted of 33±10% large, 48±6% intermediate and 19±8% small HDL. After adjusting for baseline HDL subclass distribution, body mass index, LDL-C and the ratio triglycerides/HDL-C, there was a significant increase in large HDL by about 3.9 percentage points (P<0.05) and a decrease in intermediate HDL by about 3.5 percentage points (P<0.01) in both simvastatin-containing treatment arms in comparison to ezetimibe. The parameters obtained after additional adjustment for the decrease in LDL-C indicated that about one third to one half of these effects could be explained by the extent of LDL-C-lowering.

CONCLUSIONS

In healthy men, treatment with simvastatin leads to favorable effects on HDL subclass composition, which was not be observed with ezetimibe. Part of these differential effects may be due to the stronger LDL-C-lowering effects of simvastatin.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00317993.

Atorvastatin inhibits hyperglycemia-induced expression of osteopontin in the diabetic rat kidney via the p38 MAPK pathway

Osteopontin (OPN), a large phosphoglycoprotein adhesion molecule, which is up-regulated in the kidneys of humans and mice with diabetes, has emerged as a potentially key pathophysiological contributor in diabetic nephropathy. Here, we investigated the role of OPN in kidney injury caused by diabetic nephropathy and the effect of atorvastatin on the expression of OPN and on diabetic nephropathy. Diabetes was induced with streptozotocin in rats, and atorvastatin (5 mg/kg) was orally administered once a day for 8 weeks. We analyzed the expression and regulation of OPN in the kidneys of streptozotocin-induced diabetic Sprague-Dawley albino rats by immunohistochemistry and western blot analysis. The expression of OPN was increased in diabetic rat kidney, and atorvastatin inhibited this process. Atorvastatin also decreased the expression and phosphorylation of p38. In vitro, atorvastatin inhibited the high glucose-induced OPN expression in Madin-Darby canine kidney epithelial cells through the p38 MAPK signaling pathway. These results suggested that atorvastatin reduced the expression of OPN through inhibition of the p38 MAPK pathway. The expression of OPN was associated with kidney injury. These molecules may represent therapeutic targets for the prevention of acute kidney injury induced by diabetes.

Torcetrapib/atorvastatin combination therapy

Elevated blood levels of low-density lipoprotein cholesterol (LDL-C) are associated with an increased risk for atherosclerotic coronary heart disease (CHD). Atorvastatin is a statin drug that inhibits 3-hydroxy-3-methyl-glutaryl coenzyme A reductase (the rate-limiting step of cholesterol production) and primarily lowers LDL-C levels. Atorvastatin has also been shown to significantly reduce CHD events. However, as with all statins (and all other monotherapy lipid-altering drugs), atorvastatin alone reduces the risk of CHD in only a minority of patients relative to placebo. Conversely, it is low levels of high-density lipoprotein cholesterol that are associated with increased CHD risk. Torcetrapib is a cholesteryl ester transfer protein inhibitor that primarily raises high-density lipoprotein cholesterol levels, and cholesteryl ester transfer protein inhibition has generally been shown to reduce atherosclerosis in rabbits. Taken together, atorvastatin and torcetrapib provide striking improvements in lipid levels, and complementary actions upon important lipid parameters. This review examines the chemistry, mechanism of action, pharmacokinetics, metabolism, safety/tolerability and efficacy of the combination torcetrapib/atorvastatin agent that is currently in development and that provides complementary lipid benefits towards the goal of reducing CHD risk beyond that of atorvastatin alone.

Regression of atherosclerosis: insights from animal and clinical studies

BACKGROUND

Based on studies that date back to the 1920s, regression and stabilization of atherosclerosis in humans has gone from just a dream to one that is achievable. Review of the literature indicates that the successful attempts at regression generally applied robust measures to improve plasma lipoprotein profiles. Examples include extensive lowering of plasma concentrations of atherogenic apolipoprotein B and enhancement of reverse cholesterol transport from atheromata to the liver.

FINDINGS

Possible mechanisms responsible for lesion shrinkage include decreased retention of atherogenic apolipoprotein B within the arterial wall, efflux of cholesterol and other toxic lipids from plaques, emigration of lesional foam cells out of the arterial wall, and influx of healthy phagocytes that remove necrotic debris as well as other components of the plaque. This review will highlight the role key players such as LXR, HDL and CCR7 have in mediating regression.

CONCLUSION

Although much progress has been made, there are many unanswered questions. There is, therefore, a clear need for preclinical and clinical testing of new agents expected to facilitate atherosclerosis regression with the hope that additional mechanistic insights will allow further progress.

The Therapeutic Role of Niacin in Dyslipidemia Management

There is abundant epidemiologic evidence to support the independent, inverse relationship between low levels of high-density lipoprotein cholesterol (HDL-C) and incident cardiovascular (CV) risk, the clinical importance of which is underscored by the high prevalence of low HDL-C in populations with coronary heart disease (CHD), with or without elevated levels of low-density lipoprotein cholesterol (LDL-C). The National Cholesterol Education Program recommended that optimal treatment for high-risk patients includes both lowering LDL-C and non-HDL-C to risk stratified levels and raising HDL-C when it is <40 mg/dL, although no target level for the latter lipoprotein was suggested. Niacin is the most powerful agent currently available for raising low levels of HDL-C. It also induces significant reductions in triglycerides, lipoprotein(a), and LDL-C levels while also favorably altering LDL particle size and number. In the Coronary Drug Project, niacin treatment was associated with significant reductions in CV events and long-term mortality, similar to the reductions seen in the statin monotherapy trials. In combination trials, niacin plus a statin or bile acid sequestrant produces additive reductions in CHD morbidity and mortality and promotes regression of coronary atherosclerosis. Recently, 2 clinical outcome trials (Atherothrombosis Intervention in Metabolic Syndrome With Low HDL/High Triglycerides and Impact on Global Health Outcomes [AIM-HIGH] and Second Heart Protection Study [HPS-2 THRIVE]) failed to show a reduction in CV events in patients treated to optimally low levels of LDL-C. Despite favorable effects on HDL-C and triglycerides, these studies did not demonstrate incremental clinical benefit with niacin when added to simvastatin, although notable limitations were identified in each of these trials. Thus, there is insufficient evidence from clinical trials to recommend HDL-targeted therapy for additional event reduction at the present time. However, niacin should continue to be used as an adjuvant therapy for reducing atherogenic lipoprotein burden in patients who have not reached their risk stratified LDL-C and non-HDL-C targets.

Systematic review: Evaluating the effect of lipid-lowering therapy on lipoprotein and lipid values

PURPOSE

This systematic review was performed to summarize published experience using low density lipoprotein particle number (LDL-P) to monitor the efficacy of lipid-lowering pharmacotherapies.

METHODS

Studies were identified from a literature search of MEDLINE (January 1, 2000 - June 30, 2012); and abstract searches of select conferences. All accepted studies reported mean (or median) nuclear magnetic resonance (NMR)-based LDL-P values for at least 10 subjects receiving lipid lowering pharmacotherapy.

RESULTS

Searches revealed 36 studies (with 61 treatment arms) in which LDL-P measurements were reported pre- and post-treatment. Most studies also reported changes in low-density lipoprotein cholesterol (LDL-C), but fewer studies reported changes in apolipoprotein B (apoB)(n = 20) and non-HDL-C (n = 28). Treatments included statins (22 arms/15 studies), fibrates (7 arms/7 studies), niacin (7 arms/6 studies), bile acid sequestrants (5 arms/2 studies), an anti-apoB oligonucleotide (2 arms/2 studies), combination therapies (8 arms/6 studies), anti-diabetics (5 arms/4 studies), and, other treatments (5 arms/2 studies). Lipid-lowering pharmacotherapy resulted in reductions in mean LDL-P in all but two studies. In several statin studies, the percent reductions in LDL-P were smaller than reductions in LDL-C, comparable changes were reported when LDL-P and apoB, were reported.

CONCLUSIONS

Study-level data from this systemic review establish that different lipid lowering agents can lead to discordance between LDL-P and LDL-C, therefore, basing LDL-lowering therapy only on the achievement of cholesterol goals may result in a treatment gap. Therefore, the use of LDL-P for monitoring lipid-lowering therapy, particularly for statins, can provide a more accurate assessment of residual cardiovascular risk.

Recent advances in niacin and lipid metabolism

PURPOSE OF REVIEW

This review focuses on the current understanding of the physiological mechanisms of action of niacin on lipid metabolism and atherosclerosis.

RECENT FINDINGS

Emerging findings indicate that niacin decreases hepatic triglyceride synthesis and subsequent VLDL/LDL secretion by directly and noncompetitively inhibiting hepatocyte diacylglycerol acyltransferase 2. Recent studies in mice lacking niacin receptor GPR109A and human clinical trials with GPR109A agonists disproved the long believed hypothesis of adipocyte triglyceride lipolysis as the mechanism for niacin's effect on serum lipids. Niacin, through inhibiting hepatocyte surface expression of β-chain ATP synthase, inhibits the removal of HDL-apolipoprotein (apo) AI resulting in increased apoAI-containing HDL particles. Additional recent findings suggest that niacin by increasing hepatic ATP-binding cassette transporter A1-mediated apoAI lipidation increases HDL biogenesis, thus stabilizing circulation of newly secreted apoAI. New concepts have also emerged on lipid-independent actions of niacin on vascular endothelial oxidative and inflammatory events, myeloperoxidase release from neutrophils and its impact on HDL function, and GPR109A-mediated macrophage inflammatory events involved in atherosclerosis.

SUMMARY

Recent advances have provided physiological mechanisms of action of niacin on lipid metabolism and atherosclerosis. Better understanding of niacin's actions on multiple tissues and targets may be helpful in designing combination therapy and new treatment strategies for atherosclerosis.

Colesevelam improved lipoprotein particle subclasses in patients with prediabetes and primary hyperlipidaemia

BACKGROUND

A randomised, double-blind, placebo-controlled study evaluated lipid- and glucose-lowering effects of colesevelam in patients with prediabetes and primary hyperlipidaemia. We report the effect of colesevelam on lipoprotein particle concentration and particle size (determined by nuclear magnetic resonance spectroscopy) in these patients.

METHODS

Adults with prediabetes (World Health Organization criteria), low-density lipoprotein cholesterol (LDL-C) ≥ 100 mg/dL (≥2.6 mmol/L) and triglycerides < 500 mg/dL (<5.6 mmol/L) were randomised to colesevelam 3.75 g/day or placebo for 16 weeks. The intent-to-treat population comprised 103 colesevelam and 106 placebo recipients.

RESULTS

At the end of the study, mean reduction from baseline in total LDL particle concentration was significantly greater with colesevelam versus placebo (mean treatment difference: -113 nmol/L; p = 0.02). Increases in total very low-density lipoprotein particle concentration (VLDL-P) and high-density lipoprotein particle concentration (HDL-P) did not differ significantly between the groups; however, with colesevelam versus placebo, there were significantly (p < 0.05) greater increases in large and medium VLDL-P and large HDL-P and reductions in small VLDL-P. Mean size increases were significantly greater with colesevelam for VLDL (mean treatment difference: 5.3 nm; p < 0.0001) and HDL (0.1 nm; p = 0.002).

CONCLUSIONS

Colesevelam improved the overall atherogenic lipoprotein profile in adults with prediabetes and primary hyperlipidaemia, despite potentially less favourable changes in VLDL particles.

Clinical use of a carbohydrate-restricted diet to treat the dyslipidemia of the metabolic syndrome

BACKGROUND

The metabolic syndrome is characterized by an atherogenic dyslipidemia identifiable using lipoprotein subclass analysis. This study assesses the effect of a carbohydrate-restricted diet on the dyslipidemia of the metabolic syndrome in a clinical setting.

METHODS

This is a retrospective chart review of patients attending a preventive medicine clinic using lipoprotein subclass analysis (by NMR spectroscopy) to identify the atherogenic dyslipidemia. If present, patients were counseled to begin a carbohydrate-restricted diet (< 20 g/day). Patients already on statin therapy were included only if the medication dose was not changed. The outcomes were changes in body weight, fasting serum lipid profiles and serum lipoprotein subclasses.

RESULTS

Of 122 patients identified, 80 patients had complete pre- and post-treatment data. The mean (+/-SD) age was 66 +/- 9 years, baseline weight was 85 +/- 12 kg, BMI was 28.1 +/- 3.6, 73% were male, 99% were Caucasian. Sixty-five percent were taking statin medication. Carbohydrate-restriction led to a 13% reduction in total cholesterol, 16% reduction in LDL cholesterol, 38% reduction in triglycerides, and a 13% increase in HDL cholesterol (all p values < 0.001). Carbohydrate-restriction also led to a reduction in LDL particle concentration of 28%, a reduction in small LDL of 82%, a reduction of large VLDL of 62%, and an increase in large HDL of 30% (all p values < 0.001).

CONCLUSIONS

A carbohydrate-restricted diet recommendation led to improvements in lipid profiles and lipoprotein subclass traits of the metabolic syndrome in a clinical outpatient setting, and should be considered as a treatment for the metabolic syndrome.

Niacin: the evidence, clinical use, and future directions

The use of FDA-approved niacin (nicotinic acid or vitamin B3) formulations at therapeutic doses, alone or in combination with statins or other lipid therapies, is safe, improves multiple lipid parameters, and reduces atherosclerosis progression. Niacin is unique as the most potent available lipid therapy to increase high-density lipoprotein (HDL) cholesterol and it significantly reduces lipoprotein(a). Through its action on the GPR109A receptor, niacin may also exert beneficial pleiotropic effects independent of changes in lipid levels, such as improving endothelial function and attenuating vascular inflammation. Studies evaluating the impact of niacin in statin-naïve patients on cardiovascular outcomes, or alone and in combination with statins or other lipid therapies on atherosclerosis progression, have been universally favorable. However, the widespread use of niacin to treat residual lipid abnormalities such as low HDL cholesterol, when used in combination with statins among patients achieving very low (<75 mg/dL) low-density lipoprotein cholesterol levels, is currently not supported by clinical outcome trials.

Extended-release niacin/laropiprant effects on lipoprotein subfractions in patients with type 2 diabetes mellitus

BACKGROUND

A potentially atherogenic lipid profile often found in patients with type 2 diabetes mellitus (T2DM) includes increased concentrations of small, low-density lipoprotein (LDL) and intermediate-density lipoprotein (IDL) and decreased concentration of medium/large high-density lipoprotein (HDL) particles. Extended-release niacin/laropiprant (ERN/LRPT) lowers LDL-cholesterol (LDL-C) and triglycerides (TG), and raises HDL cholesterol (HDL-C) levels with attenuation of niacin-induced flushing.

METHODS

Plasma HDL, LDL, IDL, very-low-density lipoprotein (VLDL), and chylomicron particle concentration and size at were evaluated at baseline and week 12 using nuclear magnetic resonance (NMR). The data were acquired from a randomized, multicenter, double-blind, placebo-controlled study including 796 patients with T2DM treated with either 1 tablet of ERN 1 gram/LRPT 20 mg or matching placebo daily, increased after 4 weeks to 2 tablets daily.

RESULTS

ERN/LRPT significantly (P≤0.001 for all) reduced LDL-C 17.9% and TG 23.1%, and increased HDL-C levels 23.2%. Compared to placebo, ERN/LRPT decreased LDL, IDL, VLDL, and chylomicron particle concentrations [median concentration of smallest LDL particles decreased 16.6%, 95% confidence interval (CI) -22.3, -10.9, whereas the largest LDL particles decreased 11.0%, 95% CI -18.7, -3.2, and total VLDL/chylomicron mean plasma particle concentration decreased 34.7%, 95% CI -41.3, -28.1]. Compared to placebo, ERN/LRPT shifted the distribution of HDL particle diameter from smaller to larger (median concentration of the largest HDL particles increased 32.7% (95% CI 25.30, 40.58), whereas concentration of the smallest HDL particles decreased 8.2% (95% CI -11.29, -5.06).

CONCLUSIONS

Compared with placebo in patients with T2DM, ERN/LRPT shifted the lipoprotein profile toward a potentially less atherogenic pattern with reduced atherogenic LDL and IDL particle concentrations, and increased large HDL plasma particle concentrations. (ClinicalTrials.gov: NCT00485758).

Effects of coadministered extended-release niacin/laropiprant and simvastatin on lipoprotein subclasses in patients with dyslipidemia

BACKGROUND

The use of extended-release niacin and the prostaglandin D₂ receptor antagonist laropiprant (ERN/LRPT) reduces niacin-induced flushing in patients while preserving its lipid-modifying effects.

OBJECTIVE

This predefined exploratory analysis examined the individual and combined effects of ERN/LRPT and simvastatin (SIM) on lipoprotein subclasses.

METHODS

This double-blind study randomized 1398 dyslipidemic patients equally to ERN/LRPT 1 g/20 mg, SIM (10, 20, or 40 mg), or ERN/LRPT 1 g/20 mg + SIM (10, 20, or 40 mg) once daily for 4 weeks. At week 5, doses were doubled, except SIM 40 mg (unchanged) and ERN/LRPT 1 g/20 mg + SIM 40 mg (switched to ERN/LRPT 2 g/40 mg + SIM 40 mg). Cholesterol associated with lipoprotein subclasses was quantified by vertical auto profile II (VAP II).

RESULTS

ERN/LRPT + SIM and SIM alone lowered LDL-C 1 and 3, whereas the effects were variable for ERN/LRPT; all three treatments increased LDL-C 4. ERN/LRPT + SIM and ERN/LRPT raised HDL-C 2 and 3, with greater relative percent changes in HDL 2 than HDL 3. ERN/LRPT + SIM for 12 weeks produced substantial reductions in IDL-C, which was additive compared with each monotherapy.

CONCLUSION

Coadministered ERN/LRPT + SIM produced marked reductions in atherogenic lipoproteins, with the greatest effect on IDL-C, and increases in protective HDL subclasses.

Clinical applications of advanced lipoprotein testing in diabetes mellitus

Traditional lipid profiles often fail to fully explain the elevated cardiovascular risk of individuals with diabetes mellitus. Advanced lipoprotein testing offers a novel means to evaluate dyslipidemia and refine risk estimation. Numerous observational studies have demonstrated a characteristic pattern of elevated levels of small, dense LDL particles, out of proportion to traditional lipid levels, in patients with both diabetes mellitus and the metabolic syndrome. Commonly used glucose and lipid-lowering agents have varied effects in patients with diabetes on both LDL and HDL subfractions. The exact role of advanced lipoprotein testing in patients with diabetes mellitus and the metabolic syndrome remains unclear but may offer improved assessment of cardiovascular risk compared with traditional lipid measurements.

Important considerations for treatment with dietary supplement versus prescription niacin products

Niacin is a water-soluble B vitamin (B3) known to have favorable effects on multiple lipid parameters, including raising high-density lipoprotein cholesterol (HDL-C) levels and lowering triglycerides (TGs), lipoprotein(a), and low-density lipoprotein cholesterol (LDL-C). Although LDL-C remains the primary target of lipid-altering therapy, current guidelines emphasize HDL-C and other modifiable lipid factors as key secondary targets. Thus, niacin is considered an important therapeutic option to help reduce the risk of cardiovascular disease in patients with mixed dyslipidemia who, in addition to high LDL-C, have elevated TGs and low HDL-C. Although available prescription niacin products, including immediate-release niacin (IR; Niacor) and an extended-release niacin formulation (Niaspan), have demonstrated safety and efficacy in randomized clinical trials, confusion remains among health care providers and their patients regarding the various commercially available nonprescription dietary supplement niacin products. These dietary supplements, which include IR, sustained-release (SR), and "no-flush" or "flush-free" niacin products, are not subject to the same stringent US Food and Drug Administration regulations as prescription drugs. In fact, both the American Heart Association and the American Pharmacists Association recommend against the use of dietary supplement niacin as a substitute for prescription niacin. Although some dietary supplement IR and SR niacin products have demonstrated a lipid response in clinical trials, products labeled as "no-flush" or "flush-free" that are intended to avoid the common niacin-associated adverse effect of flushing generally contain minimal or no free, pharmacologically active niacin and therefore lack beneficial lipid-modifying effects. To clarify important differences between available prescription and dietary supplement niacin products, this article contrasts current regulatory standards for dietary supplements and prescription drugs and provides an overview of available clinical data from key trials of niacin.

Pitavastatin: evidence for its place in treatment of hypercholesterolemia

Statins, inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, are the most potent pharmacologic agents for lowering total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C). They have become an accepted standard of care in the treatment of patients with known atherosclerotic cardiovascular disease (secondary prevention) and also those at increased risk of cardiovascular events. There are currently six statin drugs commercially available in the US. Although they are chemically similar and have the same primary mechanisms of action in lowering TC and LDL-C, there are differences in their efficacy or potency, metabolism, drug-drug interactions, and individual tolerability. Considering the numbers of patients who need LDL-C-lowering therapy and questions of individual tolerance and therapeutic response, having a variety of agents to choose from is beneficial for patient care. This paper presents background information on statin treatment and reviews data regarding a new agent, pitavastatin, which has recently been approved for clinical use.

Effects of cardiovascular lifestyle change on lipoprotein subclass profiles defined by nuclear magnetic resonance spectroscopy

Background

Low-density lipoprotein (LDL) cholesterol lowering is a primary goal in clinical management of patients with cardiovascular disease, but traditional cholesterol levels may not accurately reflect the true atherogenicity of plasma lipid profiles. The size and concentration of lipoprotein particles, which transport cholesterol and triglycerides, may provide additional information for accurately assessing cardiovascular risk. This study evaluated changes in plasma lipoprotein profiles determined by nuclear magnetic resonance (NMR) spectroscopy in patients participating in a prospective, nonrandomized lifestyle modification program designed to reverse or stabilize progression of coronary artery disease (CAD) to improve our understanding of lipoprotein management in cardiac patients.

Results

The lifestyle intervention was effective in producing significant changes in lipoprotein subclasses that contribute to CAD risk. There was a clear beneficial effect on the total number of LDL particles (-8.3%, p < 0.05 compared to matched controls), small dense LDL particles (-9.5%, p < 0.05), and LDL particle size (+0.8%; p < 0.05). Likewise, participants showed significant improvement in traditional CAD risk factors such as body mass index (-9.9%, p < 0.01 compared to controls), total cholesterol (-5.5%, p < 0.05), physical fitness (+37.2%, p < 0.01), and future risk for CAD (-7.9%, p < 0.01). Men and women responded differently to the program for all clinically-relevant variables, with men deriving greater benefit in terms of lipoprotein atherogenicity. Plasma lipid and lipoprotein responses to the lifestyle change program were not confounded by lipid-lowering medications.

Conclusion

In at risk patients motivated to participate, an intensive lifestyle change program can effectively alter traditional CAD risk factors and plasma lipoprotein subclasses and may reduce risk for cardiovascular events. Improvements in lipoprotein subclasses are more evident in men compared to women.

Atheroprotective lipoprotein effects of a niacin-simvastatin combination compared to low- and high-dose simvastatin monotherapy

BACKGROUND

Niacin has multiple lipoprotein effects that may provide cardiovascular benefit when added to statin monotherapy.

METHODS

In this randomized, placebo-controlled trial (n = 75) of magnetic resonance imaging of carotid atherosclerosis, we performed a secondary comparison of combination niacin-statin (simvastatin 20 mg/Niacin-ER 2G [S20/N]) to monotherapy with moderate (20 mg [S20]) and high-dose (80 mg [S80]) simvastatin on lipids, apolipoproteins (apo), low density lipoprotein (LDL) and high density lipoprotein (HDL) particle subclasses, and inflammatory markers.

RESULTS

At baseline, average age was 71, 72% were male, 62.5% used statins, and average LDL-cholesterol was 111 mg/dL. At 12 months, S20/N, compared to S80, significantly reduced apoB (-36.6% vs -11.9%; P = .05) and lipoprotein(a) (-18% vs +3.5%; P = .001) and had at least an equivalent effect on LDL-cholesterol (-39.3% vs -24.3%; P = .24). The combination reduced the proportion of subjects with atherogenic LDL pattern-B (50% to 11.5%) compared to S80 (56% to 56%) (P = .01). Despite increases in plasma free fatty acids (+62.4%; F = 5.65, P = .005 vs S20 and S80), plasma triglycerides (-29.4%; F = 6.88, P = .002 vs S20 and S80), and very-low-density lipoprotein (-44.2%; F = 7.94, P < .001 vs S20 and S80), levels were reduced by S20/N. S20/N increased HDL-cholesterol levels (+18.1%) as compared to S20 (0%) and S80 (+5.9%) (P < .001 vs both statin arms), largely due to an increase in HDL particle size (+4.6%; P = .01 vs both statin arms).

CONCLUSIONS

We demonstrate that full-dose niacin/moderate-dose simvastatin combination has sustained benefits on atherogenic apoB lipoproteins, at least comparable to high-dose simvastatin, while also raising HDL-cholesterol. Results of large clinical trials will inform whether niacin-statin combinations reduce cardiovascular disease events.

Extended-release niacin reduces LDL particle number without changing total LDL cholesterol in patients with stable CAD

BACKGROUND

The importance of the number of circulating low-density lipoprotein (LDL) cholesterol particles, in addition to total LDL level, has been increasingly recognized. The effects of extended-release niacin (ERN) on LDL particle numbers have not been studied.

OBJECTIVE

To evaluate ERN's effects on LDL particle numbers.

METHODS

Fifty-four patients with stable coronary artery disease (CAD) and well-controlled LDL levels were randomly assigned to 3 months of ERN (1 g/day) or placebo in addition to their baseline medications. Lipoprotein particle number was analyzed by proton nuclear magnetic resonance spectroscopy at baseline and after 3 months.

RESULTS

Compared to baseline, the addition of ERN had no significant effect on total LDL cholesterol levels; however, ERN decreased the number of medium and small LDL particles (P < .005). After 3 months, ERN decreased the number of medium and small LDL particles compared to placebo-treated patients (P < .05). ERN raised HDL cholesterol levels by 2.7%, significantly increased the number of large HDL particles (P < .001), and decreased the number of small HDL particles (P = .027) compared to placebo. There were no significant changes in lipid values or particle numbers in the placebo-treated patients. In patients with stable coronary artery disease and well-controlled LDL cholesterol levels, ERN reduced the number of circulating particles of the more atherogenic subtypes of LDL, despite having no effect on total LDL cholesterol levels. ERN also favorably altered the number of HDL particles.

CONCLUSION

ERN-induced alterations in lipoprotein particle numbers may contribute to its anti-atherosclerotic effects, and these effects may not be evident from the standard lipid profile.

Mechanism of action of niacin

Nicotinic acid (niacin) has long been used for the treatment of lipid disorders and cardiovascular disease. Niacin favorably affects apolipoprotein (apo) B-containing lipoproteins (eg, very-low-density lipoprotein [VLDL], low-density lipoprotein [LDL], lipoprotein[a]) and increases apo A-I-containing lipoproteins (high-density lipoprotein [HDL]). Recently, new discoveries have enlarged our understanding of the mechanism of action of niacin and challenged older concepts. There are new data on (1) how niacin affects triglycerides (TGs) and apo B-containing lipoprotein metabolism in the liver, (2) how it affects apo A-I and HDL metabolism, (3) how it affects vascular anti-inflammatory events, (4) a specific niacin receptor in adipocytes and immune cells, (5) how niacin causes flushing, and (6) the characterization of a niacin transport system in liver and intestinal cells. New findings indicate that niacin directly and noncompetitively inhibits hepatocyte diacylglycerol acyltransferase-2, a key enzyme for TG synthesis. The inhibition of TG synthesis by niacin results in accelerated intracellular hepatic apo B degradation and the decreased secretion of VLDL and LDL particles. Previous kinetic studies in humans and recent in vitro cell culture findings indicate that niacin retards mainly the hepatic catabolism of apo A-I (vs apo A-II) but not scavenger receptor BI-mediated cholesterol esters. Decreased HDL-apo A-I catabolism by niacin explains the increases in HDL half-life and concentrations of lipoprotein A-I HDL subfractions, which augment reverse cholesterol transport. Initial data suggest that niacin, by inhibiting the hepatocyte surface expression of beta-chain adenosine triphosphate synthase (a recently reported HDL-apo A-I holoparticle receptor), inhibits the removal of HDL-apo A-I. Recent studies indicate that niacin increases vascular endothelial cell redox state, resulting in the inhibition of oxidative stress and vascular inflammatory genes, key cytokines involved in atherosclerosis. The niacin flush results from the stimulation of prostaglandins D(2) and E(2) by subcutaneous Langerhans cells via the G protein-coupled receptor 109A niacin receptor. Although decreased free fatty acid mobilization from adipose tissue via the G protein-coupled receptor 109A niacin receptor has been a widely suggested mechanism of niacin to decrease TGs, physiologically and clinically, this pathway may be only a minor factor in explaining the lipid effects of niacin.

Discovery and combinatorial synthesis of fungal metabolites beauveriolides, novel antiatherosclerotic agents

For discovery of a new type of antiatherosclerotic agents, a cell-based assay of lipid droplet accumulation using primary mouse peritoneal macrophages was conducted as a model of macrophage-derived foam cell accumulation, which occurs in the early stage of atherosclerogenesis. During the screening of microbial metabolites for inhibitors of lipid droplet accumulation, 13-membered cyclodepsipeptides, known beauveriolide I and new beauveriolide III, were isolated from the culture broth of fungal Beauveria sp. FO-6979, a soil isolate, by solvent extraction, ODS column chromatography, silica gel column chromatography, and preparative HPLC. The structure including the absolute stereochemistry of beauveriolide III was elucidated as cyclo-[(3 S,4 S)-3-hydroxy-4-methyloctanoyl- l-phenylalanyl- l-alanyl- d-alloisoleucyl] by spectral analyses, amino acid analyses, and synthetic methods. Furthermore, the absolute stereochemistry was confirmed by the total synthesis of beauveriolides. Study on the mechanism of action revealed that beauveriolides inhibited macrophage acyl-CoA:cholesterol acyltransferase (ACAT) activity to block the synthesis of cholesteryl ester (CE), leading to a reduction of lipid droplets in macrophages. There are two ACAT isozymes in mammals, ACAT1 and ACAT2. ACAT1 is ubiquitously expressed in most tissues and cells including macrophages, while ACAT2 is expressed predominantly in the liver (hepatocytes) and the intestine (enterocytes). Interestingly, beauveriolides inhibited both ACAT1 and ACAT2 to a similar extent in an enzyme assay that utilized microsomes but inhibited ACAT1 selectively in intact cell-based assays. Beauveriolides proved orally active in both low-density lipoprotein receptor and apolipoprotein E knockout mice, reducing the atheroma lesion of heart and aorta without any side effects such as diarrhea or cytotoxicity to adrenal tissues as observed for many synthetic ACAT inhibitors. To obtain more potent inhibitors, a focused library of beauveriolide analogues was prepared by combinatorial chemistry in which solid-phase assembly of linear depsipeptides was carried out using a 2-chlorotrityl linker, followed by solution-phase cyclization, yielding 104 beauveriolide analogues. Among them, diphenyl derivatives were found to show 10 times more potent inhibition of CE synthesis in macrophages than beauveriolide III. Furthermore, most analogues showed selective ACAT1 inhibition or inhibition of both ACAT1 and ACAT2, but interestingly certain analogues gave selective ACAT2 inhibition. These data indicated that subtle structural differences of the inhibitors could discriminate the active sites of the ACAT1 and ACAT2 isozymes. Efforts of further analogue synthesis would make it possible to obtain highly selective ACAT1/ACAT2 inhibitors.

Nicotinic acid (niacin) receptor agonists: will they be useful therapeutic agents?

Nicotinic acid (niacin) favorably affects very-low-density lipoprotein (VLDL), low-density lipoprotein (LDL), and lipoprotein (a) (LP[a]) and increases high-density lipoprotein (HDL). Emerging data indicates vascular anti-inflammatory properties to additionally account for niacin's proven effects in cardiovascular disease. Recent evidence indicates that niacin acts on GPR109A and GPR109B (HM74A and HM74, respectively), receptors expressed in adipocytes and immune cells. In adipocytes, GPR109A activation reduces triglyceride (TG) lipolysis, resulting in decreased free fatty acid (FFA) mobilization to the liver. In humans, this mechanism has yet to be confirmed because the plasma FFA decrease is transient and is followed by a rebound increase in FFA levels. New evidence indicates niacin directly inhibits diacylglycerol acyltransferase 2 (DGAT2) isolated from human hepatocytes, resulting in accelerated hepatic apolipoprotein (apo)B degradation and decreased apoB secretion, thus explaining reductions in VLDL and LDL. This raises important questions as to whether stimulation of GPR109A in adipocytes or inhibition of DGAT2 in liver by niacin best explain the reduction in VLDL and LDL in dyslipidemic patients. Kinetic and in vitro studies indicate that niacin retards the hepatic catabolism of apoA-I but not liver scavenger receptor B1-mediated cholesterol esters, suggesting that niacin inhibits hepatic holoparticle HDL removal. Indeed, recent preliminary evidence suggests that niacin decreases surface expression of hepatic beta-chain of adenosine triphosphate synthase, which has been implicated in apoA-I/HDL holoparticle catabolism. GPR109A-mediated production of prostaglandin D2 in macrophages and Langerhan cells causes skin capillary vasodilation and explains, in part, niacin's effect on flushing. Development of niacin receptor agonists would, theoretically, result in adipocyte TG accumulation (and clinical adiposity) and increased flushing. This raises questions about niacin receptor agonists as therapeutic agents. Several niacin receptor agonists have been developed and patented, but their clinical effects have not been described. Future research is needed to determine whether niacin receptor agonists will demonstrate all the beneficial properties of nicotinic acid on atherosclerosis and without significant adverse effects.

Efficacy and tolerability of adding prescription omega-3 fatty acids 4 g/d to simvastatin 40 mg/d in hypertriglyceridemic patients: an 8-week, randomized, double-blind, placebo-controlled study

BACKGROUND

Patients with elevated serum triglyceride (TG) levels often have elevations in non-high-density lipoprotein cholesterol (non-HDL-C) levels as well. The National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) has identified non-HDL-C as a secondary therapeutic target in these patients, but treatment goals may not be reached with statin monotherapy alone.

OBJECTIVE

This study evaluated the effects on non-HDL-C and other variables of adding prescription omega-3-acid ethyl esters (P-OM3; Lovaza, formerly Omacor [Reliant Pharmaceuticals, Inc., Liberty Corner, New Jersey]) to stable statin therapy in patients with persistent hypertriglyceridemia.

METHODS

This was a multicenter, randomized, double-blind, placebo-controlled, parallel-group study in adults who had received > or = 8 weeks of stable statin therapy and had mean fasting TG levels > or = 200 and < 500 mg/dL and mean low-density lipoprotein cholesterol levels < or = 10% above their NCEP ATP III goal. The study regimen consisted of an initial 8 weeks of open-label simvastatin 40 mg/d and dietary counseling, followed by 8 weeks of randomized treatment with double-blind P-OM3 4 g/d plus simvastatin 40 mg/d or placebo plus simvastatin 40 mg/d. The main outcome measure was the percent change in non-HDL-C from baseline to the end of treatment.

RESULTS

The evaluable population included 254 patients, of whom 57.5% (146) were male and 95.7% (243) were white. The mean (SD) age of the population was 59.8 (10.4) years, and the mean weight was 92.0 (19.6) kg. At the end of treatment, the median percent change in non-HDL-C was significantly greater with P-OM3 plus simvastatin compared with placebo plus simvastatin (-9.0% vs -2.2%, respectively; P < 0.001). P-OM3 plus simvastatin was associated with significant reductions in TG (29.5% vs 6.3%) and very-low-density lipoprotein cholesterol (27.5% vs 7.2%), a significant increase in high-density lipoprotein cholesterol (HDL-C) (3.4% vs -1.2%), and a significant reduction in the total cholesterol:HDL-C ratio (9.6% vs 0.7%) (all, P < 0.001 vs placebo). Adverse events (AEs) reported by > or= 1% of patients in the P-OM3 group that occurred with a higher frequency than in the group that received simvastatin alone were nasopharyngitis (4 [3.3%]), upper respiratory tract infection (4 [3.3%]), diarrhea (3 [2.5%]), and dyspepsia (3 [2.5%]). There was no significant difference in the frequency of AEs between groups. No serious AEs were considered treatment related.

CONCLUSION

In these adult, mainly white patients with persistent hypertriglyceridemia, P-OM3 plus simvastatin and dietary counseling improved non-HDL-C and other lipid and lipoprotein parameters to a greater extent than simvastatin alone.

Pioglitazone and rosiglitazone have different effects on serum lipoprotein particle concentrations and sizes in patients with type 2 diabetes and dyslipidemia

OBJECTIVE

Associated with insulin resistance in type 2 diabetes are increased serum triglycerides, decreased HDL cholesterol, and a predominance of large VLDL, small LDL, and small HDL particles. The comparative effects of thiazolidinedione insulin sensitizers on serum lipoprotein particle concentrations and sizes in type 2 diabetes are not known. We studied the effects of pioglitazone (PIO) and rosiglitazone (ROSI) treatments on serum lipoprotein particle concentrations and sizes in type 2 diabetic patients with dyslipidemia.

RESEARCH DESIGN AND METHODS

This is a prospective, randomized, double-blind, multicenter, parallel-group study. After a 4-week placebo washout period, patients randomized to PIO (n = 369) were treated with 30 mg q.d. for 12 weeks followed by 45 mg q.d. for another 12 weeks, while patients randomized to ROSI (n = 366) were treated with 4 mg q.d. followed by 4 mg b.i.d. for the same intervals. Lipoprotein subclass particle concentrations and sizes were determined by proton nuclear magnetic resonance spectroscopy at baseline and end point (PIO [n = 333] and ROSI [n = 325] patients).

RESULTS

PIO treatment increased total VLDL particle concentration less than ROSI treatment and decreased VLDL particle size more than ROSI. PIO treatment reduced total LDL particle concentration, whereas ROSI treatment increased it. Both treatments increased LDL particle size, with PIO treatment having a greater effect. Whereas PIO treatment increased total HDL particle concentration and size, ROSI treatment decreased them; both increased HDL cholesterol levels.

CONCLUSIONS

PIO and ROSI treatments have different effects on serum lipoprotein subclass particle concentrations and sizes in patients with type 2 diabetes and dyslipidemia.

Pharmacologic characteristics of statins

Considerable effort has been devoted to improving the pharmacologic characteristics and clinical effects of statins. Desirable pharmacologic properties include potent inhibition of hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase, selectivity of uptake in hepatocytes, low systemic bioavailability to reduce systemic adverse effects, prolonged elimination half-life, and no or minimal hepatic metabolism to avoid drug-drug interactions. The desirable effects on lipid variables would include increased effectiveness in reducing levels of low-density lipoprotein cholesterol and other atherogenic lipoproteins and measurable beneficial effects on high-density lipoprotein cholesterol levels. As a product of the ongoing efforts regarding statin pharmacology, the new statin rosuvastatin exhibits significant improvements in several of these characteristics.

The Effects of Niacin on Lipoprotein Subclass Distribution

Dyslipidemia is a heterogeneous metabolic condition; high-density lipoprotein (HDL), low-density lipoprotein (LDL), and very-low-density lipoprotein represent families of lipoprotein particles that differ in size and composition and vary in atherogenicity. Lipoprotein subclasses containing apolipoprotein B promote atherosclerosis, of which the most atherogenic appear to be the small, dense LDL and large very-low-density lipoprotein subclasses, while the large HDL2 subclass, which transports esterified cholesterol from the periphery to the liver, is considered the more cardioprotective. Niacin has long been known to improve concentrations of all major lipids and lipoproteins, but it also has consistently favorable effects on subclass distribution. A MEDLINE search was conducted for clinical studies reporting the effects of niacin on lipoprotein subclasses. The niacin-associated elevations in HDL cholesterol likely stem from differential drug effects on subclasses, producing favorable changes in levels of HDL2 and apolipoprotein A-I. Niacin has more moderate LDL cholesterol-lowering efficacy, but this change is associated with an increase in LDL particle size and a shift from small LDL to the less atherogenic, large LDL subclasses. In addition, it also tends to decrease concentrations of the larger very-low-density lipoprotein subclasses. Niacin confers diverse benefits with respect to both the quantity and quality of lipid and lipoprotein particles.

Anti-inflammatory effect is an important property of niacin on atherosclerosis beyond its lipid-altering effects

Niacin has been used for decades to lower the plasma concentrations of cholesterol, free fatty acids, and triglycerides in humans, and in addition it raises more than any other drug the levels of the protective high density lipoprotein. These effects have been used to treat dyslipidemic states. Trials have shown that treatment with niacin reduces progression of atherosclerosis, and clinical events and mortality from coronary heart disease. The beneficial clinical efficacy of niacin appropriately emphasizes the prominent role of its lipid-altering effects; however, high expression of niacin receptor in a variety of immune cell types, lowering of inflammatory markers, and beneficial impact on adipokines expression could provide rational to the hypothesis that anti-inflammatory effect is also an important property of niacin on atherosclerosis beyond its lipid-altering effects.

Clinical importance and therapeutic modulation of small dense low-density lipoprotein particles

The National Cholesterol Education Programme Adult Treatment Panel III accepted the predominance of small dense low-density lipoprotein (sdLDL) as an emerging cardiovascular disease (CVD) risk factor. Most studies suggest that measuring low-density lipoprotein (LDL) particle size, sdLDL cholesterol content and LDL particle number provides additional assessment of CVD risk. Therapeutic modulation of small LDL size, number and distribution may decrease CVD risk; however, no definitive causal relationship is established, probably due to the close association between sdLDL and triglycerides and other risk factors (e.g., high-density lipoprotein, insulin resistance and diabetes). This review addresses the formation and measurement of sdLDL, as well as the relationship between sdLDL particles and CVD. The effect of hypolipidaemic (statins, fibrates and ezetimibe) and hypoglycaemic (glitazones) agents on LDL size and distribution is also discussed.

Functionally defective high-density lipoprotein: a new therapeutic target at the crossroads of dyslipidemia, inflammation, and atherosclerosis

High-density lipoproteins (HDL) possess key atheroprotective biological properties, including cellular cholesterol efflux capacity, and anti-oxidative and anti-inflammatory activities. Plasma HDL particles are highly heterogeneous in physicochemical properties, metabolism, and biological activity. Within the circulating HDL particle population, small, dense HDL particles display elevated cellular cholesterol efflux capacity, afford potent protection of atherogenic low-density lipoprotein against oxidative stress and attenuate inflammation. The antiatherogenic properties of HDL can, however be compromised in metabolic diseases associated with accelerated atherosclerosis. Indeed, metabolic syndrome and type 2 diabetes are characterized not only by elevated cardiovascular risk and by low HDL-cholesterol (HDL-C) levels but also by defective HDL function. Functional HDL deficiency is intimately associated with alterations in intravascular HDL metabolism and structure. Indeed, formation of HDL particles with attenuated antiatherogenic activity is mechanistically related to core lipid enrichment in triglycerides and cholesteryl ester depletion, altered apolipoprotein A-I (apoA-I) conformation, replacement of apoA-I by serum amyloid A, and covalent modification of HDL protein components by oxidation and glycation. Deficient HDL function and subnormal HDL-C levels may act synergistically to accelerate atherosclerosis in metabolic disease. Therapeutic normalization of attenuated antiatherogenic HDL function in terms of both particle number and quality of HDL particles is the target of innovative pharmacological approaches to HDL raising, including inhibition of cholesteryl ester transfer protein, enhanced lipidation of apoA-I with nicotinic acid and infusion of reconstituted HDL or apoA-I mimetics. A preferential increase in circulating concentrations of HDL particles possessing normalized antiatherogenic activity is therefore a promising therapeutic strategy for the treatment of common metabolic diseases featuring dyslipidemia, inflammation, and premature atherosclerosis.

Beneficial effect of simvastatin treatment on LDL oxidation and antioxidant protection is more pronounced in combined hyperlipidemia than in hypercholesterolemia

AIMS

Beneficial effects of statin treatment on cardiovascular morbidity and mortality has been not entirely explained by the reduction in LDL-cholesterol level. We hypothesised that antioxidant activity of statins may contribute to their salutary cardiovascular effects. The aim of the present study was to examine effect of simvastatin treatment on some parameters of LDL oxidation and antioxidant protection in patients with hypercholesterolemia and combined hyperlipidemia. Furthermore, we were interested, whether the effect of treatment is related to the type of hyperlipidemia.

PATIENTS AND METHODS

Fourty-two patients (12 males, 30 females, mean age 60+/-10 years) were included in the present study. Fourteen patients had hypercholesterolemia defined as total cholesterol>5.0 mmol/l. Twenty-eight patients had combined hyperlipidemia defined by total cholesterol>5.0 mmol/l and triglycerides>1.7 mmol/l. Simvastatin was administered to patients during 8-week period in a daily dose of 20mg. Oxidation of LDL was measured by assessment of circulating conjugated diene (CD) and malondialdehyde (MDA) level. Antioxidant properties of blood were assessed based on measurement of total antioxidant status (TAS) and glutathione peroxidase (GPx) activity.

RESULTS

Besides expected significant decrease in total cholesterol, LDL-cholesterol, apolipoprotein B and triglyceride levels, simvastatin treatment also reduced significantly circulating CD by 41% (p<0.0001) and MDA level non-significantly by 6% (p=0.078). Simvastatin treatment resulted in an increase of GPx activity by 38% (p<0.0001), but did not have a significant effect on TAS. Patients with combined hyperlipidemia had significantly higher baseline CD (p<0.01) and consequently significantly greater absolute and relative decrease (46% versus 23%) in circulating CD (DeltaCD), when compared with patients with hypercholesterolemia. The increase in GPx activity was significant only in patients with combined hyperlipidemia (p<0.0001). In the multiple stepwise linear regression analysis, both baseline triglyceride (r(2)=0.32; p=0.004) and LDL cholesterol (r(2)=0.08; p=0.05) levels were significant independent predictors of DeltaCD after simvastatin treatment.

CONCLUSION

Simvastatin treatment significantly reduced circulating conjugated diene level and led to an increase in glutathione peroxidase activity. These effects were more pronounced in patients with combined hyperlipidemia than in hypercholesterolemia. The results suggest that simvastatin possesses certain antioxidant properties, which may contribute to its beneficial cardiovascular effect.

The Clinical Relevance of Low-Density-Lipoproteins Size Modulation by Statins

The predominance of small, dense low density lipoproteins (LDL) has been accepted as an emerging cardiovascular risk factor by the National Cholesterol Education Program Adult Treatment Panel III; in fact, LDL size seems to be an important predictor of cardiovascular events and progression of coronary heart disease. Several studies have also shown that the therapeutical modulation of LDL size is of great benefit in reducing the risk of cardiovascular events. Hypolipidemic treatment is able to alter LDL subclass distribution and statins are currently the most widely used lipid-lowering agents. Statins are potent inhibitors of hydroxy-methyl-glutaryl-coenzyme A reductase, the rate-limiting enzyme in hepatic cholesterol synthesis and are the main drugs of choice for the treatment of elevated plasma LDL cholesterol concentrations. Statins potentially lower all LDL subclasses (e.g., large, medium and small particles); thus, their net effect on LDL subclasses or size is often only moderate. However, a strong variation has been noticed among the different agents: analyses of all published studies suggest a very limited role of pravastatin and simvastatin in modifying LDL size and their subclasses, while fluvastatin and atorvastatin seem to be much more effective agents. Finally, rosuvastatin, the latest statin molecule introduced in the market, seems to be promising in altering LDL subclasses towards less atherogenic particles.

Clinical evidence for use of acetyl salicylic acid in control of flushing related to nicotinic acid treatment

Nicotinic acid (NA) is highly effective and widely used in the management of dyslipidaemia. For many patients, the side effect of flushing of the face and upper body leads to discontinuation. Flushing with NA is mediated by prostaglandins, and as acetyl salicylic acid (ASA, 'aspirin') is a highly effective inhibitor of prostaglandin synthesis, there is a rationale for its use to prevent or reduce the severity of NA-related flushing. This literature survey identified four studies specifically exploring the utility of ASA in preventing NA-related flushing in healthy volunteers. Twenty-three NA studies, where ASA was mandatory or optional within the protocol, and four studies, where background ASA therapy was reported in most participants, were also identified. Although the incidence of flushing in studies using ASA was often high, discontinuation rates due to flushing were low (mean 7.7%). This figure compares favourably with discontinuation rates with NA commonly reported in the literature (up to approximately 40%). There is good supportive evidence for the use of ASA in reducing the severity of NA-related flushing.

Paradoxical effects of fenofibrate and nicotinic acid in apo E-deficient mice

Atherosclerosis is a complex vascular disease initiated by abnormal accumulation of plasma lipoproteins in the subendothelial space. Elevated levels of plasma triglycerides (TG) and low-density lipoprotein (LDL)-cholesterol as well as low concentrations of high-density lipoprotein (HDL) play a causal role in the development and progression of atherosclerotic lesions. We have shown that apolipoprotein E-deficient (apo E-KO) mice have elevated triglyceride levels plus diminished HDL concentrations. Drugs such as fenofibrate and nicotinic acid are well known to reduce TG and increase HDL levels in humans. In this study, we investigated the beneficial effects of fenofibrate and niacin on lipid profile and atherogenesis in apo E-KO mice and their wild-type counterparts. Animals were fed with a cholesterol-enriched diet supplemented with fenofibrate (0.1% wt/wt, n = 8) or nicotinic acid (0.5% wt/wt, n = 8) for 14 weeks. Body weights were recorded weekly, and plasma lipid profiles were determined at 4-week intervals. The hearts and aortas were collected and fixed for histologic and morphometric evaluations of atherosclerotic lesions. Fenofibrate treatment in apo E-KO mice paradoxically increased total cholesterol and TG by 65% and 44%, respectively, and decreased HDL-cholesterol levels by 35% as compared with controls. Similar effects of fenofibrate on cholesterol levels, but not on TG concentrations, were observed in C57BL/6 mice. Fenofibrate-treated mice had lower body weight as compared with controls. Niacin had no effect on body weight gain but failed to decrease TG or to increase HDL levels in either apo E-KO mice or their wild-type counterparts. Neither fenofibrate nor niacin significantly influenced atherogenesis in apo E-KO mice as compared with controls. In conclusion, this study shows that neither niacin nor fenofibrate has beneficial lipid-modifying and antiatherosclerosis activities in mice. Identification of mechanisms underlying paradoxical effects of fenofibrate on lipoprotein metabolisms in apo E-KO mice merits further investigation.

The metabolic syndrome: prevalence, CHD risk, and treatment

An increased risk of coronary heart disease (CHD) morbidity and mortality is associated with the metabolic syndrome, a condition characterized by the concomitant presence of several abnormalities, including abdominal obesity, dyslipidemia, hypertension, insulin resistance (with or without glucose intolerance or diabetes), microalbuminuria, prothrombotic, and proinflammatory states. Estimates of the prevalence of the metabolic syndrome indicate that this condition is now common and likely to increase dramatically over the coming decades, in parallel with greater rates of obesity and Type 2 diabetes. Risk factors for the metabolic syndrome are already present in obese children and adolescents. Thus, identifying and treating all affected individuals promptly and optimally are critical to ensure that this potentially challenging healthcare burden is minimized. Here, we review the prevalence of the metabolic syndrome, dyslipidemias, and CHD risk. Although changes in lifestyle are fundamental to reducing many of the CHD risk factors associated with the metabolic syndrome, pharmacologic interventions also play an important role. Retrospective subanalyses of the effects of statins on coronary event rates and lipid levels in patients with the metabolic syndrome included in clinical trials indicate that these agents are beneficial in correcting the extensive lipid abnormalities that are frequently present in these individuals. However, the optimal management of metabolic syndrome dyslipidemia will depend on the outcomes of future prospective clinical trials. This review examines the underlying causes and prevalence of the metabolic syndrome and its impact on CHD morbidity and mortality and discusses the role of statins in optimizing its management.