A new paradigm for managing dyslipidemia with combination therapy: laropiprant + niacin + simvastatin

Effects of Rosuvastatin Versus Atorvastatin, Alone or in Combination, on Lipoprotein (a)

Background: There are little evidences about the therapeutic efficacy of different lipid-lowering agents in the reduction of elevated lipoprotein(a) [Lp(a)]. Objective: testing the effect of different lipid-lowering agents on elevated Lp(a). Methods: prospective interventional study performed in patients with CAD, or high CAD risk, with Lp(a), >50 mg/dL. Lp(a), total cholesterol (C), HDL-C, LDL-C, triglycerides (TGs), apolipoprotein (Apo) A1, Apo B, enzymes of myocyte and hepatic injury were comparatively analyzed between 4 lipid-lowering strategies: rosuvastatin (R group) 40 mg, atorvastatin (A group) 80 mg, atorvastatin 40 mg add-on micronized fenofibrate (A+F group), and atorvastatin 40 mg add-on 1 g extended-release niacin (A+ERN group). Comparison was made for their therapeutic efficacy on Lp(a), and safety. Results: 87 patients with mean Lp(a) 94.6 ± 39.6 mg/dL were analyzed. Groups: 25 patients in the R, 22 in the A, 20 in the A+F and 20 in A+ERN group. Significant reduction in all lipid fractions in all treatment groups was reported after 6 months. The average reduction of Lp(a) was 15.9 ± 21.0 mg/dL, with: 18.2 ± 24.8 ( P = 0.001) in the R group, 17.3 ± 10.4 (P = 0.001) in A+F, 19.5 ± 10.9 (P = 0.001) in A+ERN and the lowest in the A group (11.24 ± 22.91, P = 0.032). No adverse effects were observed in any of the treatment groups. Conclusions: When compared with atorvastatin, it seems that rosuvastatin can achieve more significant decrease of Lp(a).The efficacy of the second one can be increased by adding fibrate or ERN.

Impact of L-FABP and glucose on polyunsaturated fatty acid induction of PPARα-regulated β-oxidative enzymes

Liver fatty acid binding protein (L-FABP) is the major soluble protein that binds very-long-chain n-3 polyunsaturated fatty acids (n-3 PUFAs) in hepatocytes. However, nothing is known about L-FABP's role in n-3 PUFA-mediated peroxisome proliferator activated receptor-α (PPARα) transcription of proteins involved in long-chain fatty acid (LCFA) β-oxidation. This issue was addressed in cultured primary hepatocytes from wild-type, L-FABP-null, and PPARα-null mice with these major findings: 1) PUFA-mediated increase in the expression of PPARα-regulated LCFA β-oxidative enzymes, LCFA/LCFA-CoA binding proteins (L-FABP, ACBP), and PPARα itself was L-FABP dependent; 2) PPARα transcription, robustly potentiated by high glucose but not maltose, a sugar not taken up, correlated with higher protein levels of these LCFA β-oxidative enzymes and with increased LCFA β-oxidation; and 3) high glucose altered the potency of n-3 relative to n-6 PUFA. This was not due to a direct effect of glucose on PPARα transcriptional activity nor indirectly through de novo fatty acid synthesis from glucose. Synergism was also not due to glucose impacting other signaling pathways, since it was observed only in hepatocytes expressing both L-FABP and PPARα. Ablation of L-FABP or PPARα as well as treatment with MK886 (PPARα inhibitor) abolished/reduced PUFA-mediated PPARα transcription of these genes, especially at high glucose. Finally, the PUFA-enhanced L-FABP distribution into nuclei with high glucose augmentation of the L-FABP/PPARα interaction reveals not only the importance of L-FABP for PUFA induction of PPARα target genes in fatty acid β-oxidation but also the significance of a high glucose enhancement effect in diabetes.

Laropiprant attenuates EP3 and TP prostanoid receptor-mediated thrombus formation

The use of the lipid lowering agent niacin is hampered by a frequent flush response which is largely mediated by prostaglandin (PG) D₂. Therefore, concomitant administration of the D-type prostanoid (DP) receptor antagonist laropiprant has been proposed to be a useful approach in preventing niacin-induced flush. However, antagonizing PGD₂, which is a potent inhibitor of platelet aggregation, might pose the risk of atherothrombotic events in cardiovascular disease. In fact, we found that in vitro treatment of platelets with laropiprant prevented the inhibitory effects of PGD₂ on platelet function, i.e. platelet aggregation, Ca²⁺ flux, P-selectin expression, activation of glycoprotein IIb/IIIa and thrombus formation. In contrast, laropiprant did not prevent the inhibitory effects of acetylsalicylic acid or niacin on thrombus formation. At higher concentrations, laropiprant by itself attenuated platelet activation induced by thromboxane (TP) and E-type prostanoid (EP)-3 receptor stimulation, as demonstrated in assays of platelet aggregation, Ca²⁺ flux, P-selectin expression, and activation of glycoprotein IIb/IIIa. Inhibition of platelet function exerted by EP4 or I-type prostanoid (IP) receptors was not affected by laropiprant. These in vitro data suggest that niacin/laropiprant for the treatment of dyslipidemias might have a beneficial profile with respect to platelet function and thrombotic events in vascular disease.

Extended release niacin-laropiprant in patients with hypercholesterolemia or mixed dyslipidemias improves clinical parameters

The progression of atherosclerosis remains a major cause of morbidity and mortality. Plaque formation is an immunological response driven by a number of risk factors, and reduction of risk is the primary goal of treatment. The role of LDL-C is well established and statins have proved effective drugs, although the relative risk reduction is only around 30%. The importance of other factors-notably low HDL-C and high TGs-has become increasingly clear and the search for alternative strategies continues. Niacin is particularly effective in achieving normalization of HDL-C but is clinically underutilized due to the side effect of cutaneous flushing. The discovery that flushing is mediated by mechanisms distinct from the lipid-lowering effects has led to the development of combination drugs with reduced side effects. This review considers the evidence regarding the clinical efficacy of extended-release niacin and the DP1 antagonist laropiprant in the treatment of hypercholesterolemia and mixed dyslipidemias.

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.

Dyslipidaemia in the metabolic syndrome and type 2 diabetes: pathogenesis, priorities, pharmacotherapies

IMPORTANCE OF THE FIELD

Dyslipoproteinaemia is a cardinal feature of the metabolic syndrome that accelerates atherosclerosis. It is usually characterized by high plasma concentrations of triglyceride-rich and apolipoprotein B (apoB)-containing lipoproteins, with depressed concentrations of high-density lipoprotein (HDL). Drug interventions are essential for normalizing metabolic dyslipidaemia.

AREAS COVERED IN THIS REVIEW

This review discusses the mechanisms and treatment for dyslipidaemia in the metabolic syndrome and type 2 diabetes.

WHAT THE READER WILL GAIN

A comprehensive understanding of the pathophysiology and pharmacotherapy of dyslipidaemia in the metabolic syndrome and diabetes.

TAKE HOME MESSAGE

Dysregulation of lipoprotein metabolism may be due to a combination of overproduction of triglyceride-rich lipoproteins, decreased catabolism of apoB-containing particles, and increased catabolism of HDL particles. These abnormalities may be consequent on a global metabolic effect of insulin resistance and an excess of both visceral and hepatic fat. Lifestyle modifications may favourably alter lipoprotein transport in the metabolic syndrome. Patients with dyslipidaemia and established cardiovascular disease should receive a statin as first-line therapy. Combination with other lipid-regulating agents, such as ezetimibe, fibrates, niacins and fish oils may optimize the benefit of statin on atherogenic dyslipidaemia.