Safety of lovastatin/extended release niacin compared with lovastatin alone, atorvastatin alone, pravastatin alone, and simvastatin alone (from the United States Food and Drug Administration adverse event reporting system)

A review on the efficacy and safety of lipid-lowering drugs in neurodegenerative disease

There is a train of thought that lipid therapies may delay or limit the impact of neuronal loss and poor patient outcomes of neurodegenerative diseases (NDDs). A variety of medicines including lipid lowering modifiers (LLMs) are prescribed in NDDs. This paper summarizes the findings of clinical and observational trials including systematic reviews and meta-analyses relating to LLM use in NDDs published in the last 15 years thus providing an up-to-date evidence pool. Three databases were searched PubMed, CINAHL, and Web of Science using key terms relating to the review question. The findings confirm the benefit of LLMs in hyperlipidemic patients with or without cardiovascular risk factors due to their pleotropic effects. In NDDs LLMs are proposed to delay disease onset and slow the rate of progression. Clinical observations show that LLMs protect neurons from α-synuclein, tau, and Aβ toxicity, activation of inflammatory processes, and ultimately oxidative injury. Moreover, current meta-analyses and clinical trials indicated low rates of adverse events with LLMs when used as monotherapy. LLMs appear to have favorable safety and tolerability profiles with few patients stopping treatment due to severe adverse effects. Our collated evidence thus concludes that LLMs have a role in NDDs but further work is needed to understand the exact mechanism of action and reach more robust conclusions on where and when it is appropriate to use LLMs in NDDs in the clinic.

Lipid-lowering Therapies in Myositis

PURPOSE OF REVIEW

The use of lipid-lowering therapies in patients with idiopathic inflammatory myopathies (IIM) is complicated and there are no guidelines for diagnosing, monitoring, or treating atherosclerotic cardiovascular disease (ASCVD) in this group of patients.

RECENT FINDINGS

The use of lipid-lowering therapies, especially statins, is recommended in patients with increased risk for ASCVD, which includes patients with inflammatory diseases, based on recent American College of Cardiology/American Heart Association (ACC/AHA) guidelines for ASCVD management. There is accumulating evidence that patients with IIM are at increased risk for ASCVD, similar to other inflammatory diseases. Lipid-lowering therapies have side effects that may be pronounced or confounding in myositis patients, potentially limiting their use. Statins are specifically contraindicated in patients with anti 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) antibodies. Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors have been shown to be safe and potentially beneficial in patients with IIM. Here, we propose a framework for (1) ASCVD risk assessment and treatment based on ACC/AHA ASCVD primary prevention guidelines; (2) myositis disease monitoring while undergoing lipid-lowering therapy; and (3) management of statin intolerance, including, indications for the use of PCSK9 inhibitors.

Serious Adverse Effects of Extended-release Niacin/Laropiprant: Results From the Heart Protection Study 2-Treatment of HDL to Reduce the Incidence of Vascular Events (HPS2-THRIVE) Trial

PURPOSE

The Heart Protection Study 2-Treatment of HDL to Reduce the Incidence of Vascular Events (HPS2-THRIVE) trial of patients at high risk of vascular disease found that adding extended-release niacin-laropiprant to intensive statin-based LDL-lowering therapy had no benefit on cardiovascular outcomes. However, the trial also identified previously unrecognized serious adverse effects (including new-onset diabetes, bleeding, and infection). Our objective was to explore the safety profile of niacin-laropiprant and examine whether any patients were at lower (or higher) risk of its adverse effects.

METHODS

HPS2-THRIVE was a randomized, double-blind trial of niacin-laropiprant (2000/40 mg/d) versus placebo among 25,673 patients at high risk of vascular disease. Information on all serious adverse events was collected during a median of 3.9 years of study treatment. Effects of niacin-laropiprant on new-onset diabetes, disturbances of diabetes control, bleeding, infection, and gastrointestinal upset were estimated by (1) time after randomization, (2) severity, (3) baseline characteristics, (4) baseline risk of the adverse event of interest, and (5) risk of major vascular event.

FINDINGS

The hazard ratio (HR) for new-onset diabetes with niacin/laropiprant was 1.32 (95% CI, 1.16-1.51; P < .001), which corresponded to an absolute excess of 4 people (95% CI, 2-6) developing diabetes per 1000 person-years in the study population as a whole. Among the 8299 participants with diabetes at baseline, the HR for serious disturbances in diabetes control was 1.56 (95% CI, 1.35-1.80), corresponding to an absolute excess of 12 (95% CI, 8-16) per 1000 person-years. The HR was 1.38 (95% CI, 1.17-1.63; P < .001) for serious bleeding, corresponding to an absolute excess of 2 (95% CI, 1-3) per 1000 person-years and 1.22 (95% CI, 1.11-1.34; P < .001) for serious infection, corresponding to an absolute excess of 4 (95% CI, 2-6) per 1000 person-years. The excess risks of these serious adverse events were larger in the first year after starting niacin-laropiprant therapy than in later years (except for the excess of infection, which did not appear to attenuate with time), and the risks of nonfatal and fatal events were similarly increased. The absolute excesses of each of these adverse effects were similar regardless of the baseline risk of the outcome.

IMPLICATIONS

Practitioners or patients considering the use of niacin (in addition to, or instead of, a statin) despite the lack of evidence of cardiovascular benefits (at least when added to effective statin therapy) should take account of the significant risks of these serious adverse effects when making such decisions. ClinicalTrials.gov identifier: NCT00461630.

Product indiscriminate use of vitamin risks: A review

Most of the population does not seek professional advice before taking vitamin products and their indiscriminate use can lead to serious health risks. This study aims to demonstrate, through bibliographic survey, the risks of indiscriminate use of vitamin products related to hypervitaminosis and major drug interactions which the multivitamins are involved. A bibliographic survey was conducted in the databases LILACS, SciELO, PubMed, Medline, Micromedex, Drugs.com and textbooks on the subject. Vitamins are commonly described as harmless products by the majority of the population, but these trace elements can interact with other substances, causing mild disconforts or treatment failure for the patient, severe consequences to the body and can lead to death. To avoid the indiscriminate use of vitamin products, it is necessary that health professionals know and use specific laboratory tests for the determination of vitamins in the body, preventing these products from being unnecesarily prescribed. Also, the knowledge about what the possible effects of the indiscriminate use of vitamin supplements can lead to the rational use of these products.

Safety of statins: an update

Statins are widely used and have been proven to be effective in the prevention of atherosclerotic vascular disease events, primarily by reducing plasma low-density lipoprotein cholesterol concentrations. Although statins are generally well tolerated and present an excellent safety profile, adverse effects from muscle toxicity and liver enzyme abnormalities may occur in some patients. Myopathy and rhabdomyolysis are rare with statin monotherapy at the approved dose ranges, but the risk increases with use of higher doses, interacting drugs and genetic predisposition. Asymptomatic increases in liver transaminases with statin treatment do not seem to be associated with an increased risk of liver disease. Therefore, statin treatment can be safely used in patients with mild to moderately abnormal liver tests that are potentially attributable to nonalcoholic fatty liver disease and can improve liver tests and reduce cardiovascular morbidity in this group of patients. The risks of other unfavorable effects such as the slightly increased risk of new-onset diabetes and potentially increased risk of haemorrhagic stroke are much smaller than the cardiovascular benefits with the use of statins.

Dietary modulators of statin efficacy in cardiovascular disease and cognition

Cardiovascular disease remains the leading cause of morbidity and mortality in the United States and other developed countries, and is fast growing in developing countries, particularly as life expectancy in all parts of the world increases. Current recommendations for the prevention of cardiovascular disease issued jointly from the American Academy of Cardiology and American Heart Association emphasize that lifestyle modification should be incorporated into any treatment plan, including those on statin drugs. However, there is a dearth of data on the interaction between diet and statins with respect to additive, complementary or antagonistic effects. This review collates the available data on the interaction of statins and dietary patterns, cognition, genetics and individual nutrients, including vitamin D, niacin, omega-3 fatty acids, fiber, phytochemicals (polyphenols and stanols) and alcohol. Of note, although the available data is summarized, the scope is limited, conflicting and disparate. In some cases it is likely there is unrecognized synergism. Virtually no data are available describing the interactions of statins with dietary components or dietary pattern in subgroups of the population, particularly those who may benefit most were positive effects identified. Hence, it is virtually impossible to draw any firm conclusions at this time. Nevertheless, this area is important because were the effects of statins and diet additive or synergistic harnessing the effect could potentially lead to the use of a lower intensity statin or dose.

The current state of niacin in cardiovascular disease prevention: a systematic review and meta-regression

OBJECTIVES

This study sought to assess the efficacy of niacin for reducing cardiovascular disease (CVD) events, as indicated by the aggregate body of clinical trial evidence including data from the recently published AIM-HIGH (Atherothrombosis Intervention in Metabolic Syndrome with Low HDL/High Triglycerides: Impact on Global Health Outcomes) trial.

BACKGROUND

Previously available randomized clinical trial data assessing the clinical efficacy of niacin has been challenged by results from AIM-HIGH, which failed to demonstrate a reduction in CVD event incidence in patients with established CVD treated with niacin as an adjunct to intensive simvastatin therapy.

METHODS

Clinical trials of niacin, alone or combined with other lipid-altering therapy, were identified via MEDLINE. Odds ratios (ORs) for CVD endpoints were calculated with a random-effects meta-analyses. Meta-regression modeled the relationship of differences in on-treatment high-density lipoprotein cholesterol with the magnitude of effect of niacin on CVD events.

RESULTS

Eleven eligible trials including 9,959 subjects were identified. Niacin use was associated with a significant reduction in the composite endpoints of any CVD event (OR: 0.66; 95% confidence interval [CI]: 0.49 to 0.89; p = 0.007) and major coronary heart disease event (OR: 0.75; 95% CI: 0.59 to 0.96; p = 0.02). No significant association was observed between niacin therapy and stroke incidence (OR: 0.88; 95% CI: 0.5 to 1.54; p = 0.65). The magnitude of on-treatment high-density lipoprotein cholesterol difference between treatment arms was not significantly associated with the magnitude of the effect of niacin on outcomes.

CONCLUSIONS

The consensus perspective derived from available clinical data supports that niacin reduces CVD events and, further, that this may occur through a mechanism not reflected by changes in high-density lipoprotein cholesterol concentration.

Potential drug interactions associated with treatments for type 2 diabetes and its comorbidities: a clinical pharmacology review

Type 2 diabetes is a disease of glucose metabolism that commonly involves multiple comorbidities, including lipid dyscrasias and hypertension. Each concurrent disorder contributes some risk of complications and requires therapeutic intervention. The simultaneous management of so many coexisting illnesses can be complex and commonly results in patients being prescribed multiple medications--referred to as polypharmacy--which may further complicate treatment. To ensure the best patient outcomes, the treating physician must be aware of all the therapeutic agents that a patient is taking to assess possible drug interactions that such a plethora of medications may confer. This article addresses the underlying comorbidites, the drugs commonly used to treat them and the interactions that may arise from concomitant administration.

Public health concerns for anti-obesity medicines imported for personal use through the internet: a cross-sectional study

OBJECTIVE

To explore the circulation of anti-obesity medicines via the internet and their quality.

DESIGN

Cross-sectional study.

SETTING

Internet pharmacies and pharmaceutical suppliers accessible from Japan.

PARTICIPANTS

Anti-obesity medicines were purchased using relevant keywords on Japanese Google search engine. Blogs and advertisement-only sites were excluded.

PRIMARY AND SECONDARY OUTCOME MEASURES

The authenticity of the samples was investigated in collaboration with the manufacturers of the samples and medicine regulatory authorities. Quality of the samples was assessed by pharmacopoeial analyses using high-performance liquid chromatography.

RESULTS

82 samples were purchased from 36 internet sites. Approximately half of the sites did not mention a physical address, and 45% of the samples did not contain a package insert. A variety of custom declarations were made for the shipments of the samples: personal health items, supplement, medicines, general merchandise, tea and others. Among 82 samples, 52 samples were analysed to check their pharmacopoeial quality. Authenticity responses were received from only five of 20 manufacturing companies. According to the pharmacopoeial analyses and authenticity investigation, three of the samples were identified as counterfeits and did not contain any active ingredients. Two of these samples were confirmed as counterfeits by the manufacturer of the authentic products. The manufacturer of the other sample did not respond to our request for an authenticity check even after several communication attempts. These counterfeit cases have been reported at the rapid alert system of Western Pacific Region of the WHO.

CONCLUSIONS

Many counterfeit and unapproved anti-obesity medicines may be easily bypassing regulatory checks during shipping and are widely circulated through the internet. Regulatory authorities should take measures to prevent these medicines from entering countries to safeguard their citizens.

Preparation of lovastatin matrix sustained-release pellets by extrusion-spheronization combined with microcrystal dispersion technique

The poorly water-soluble drug lovastatin (LVA) is an inhibitor of 3-hydroxy-3-methylglutarylcoenzyme A reductase and has a slow dissolution rate. In this study, a microcrystal dispersion (MCD) technique was used in the preparation of LVA to increase its dissolution rate and then combining with an extrusion-spheronization method, microcrystalline cellulose (MCC) matrix sustained-release pellets containing LVA-MCD were developed and characterized in vitro. Photomicrographs indicated that LVA-MCD existed as fine crystals, of which the mean particle size was reduced from 65.75 μm to 3.97 μm and the dried LVA-MCD powders released completely within 2 hours. SEM results during the release process showed that pellets possessed a matrix structure and after the dissolution test, this matrix structure became loose and porous. The release of LVA was fast and complete, and accumulated release by the optimal formulation was: 0.5 h (20.23 ± 3.40%), 2 h (56.87 ± 2.85%), 4 h (78.71 ± 3.42%), and 8 h (96.81 ± 3.30%). The 3 months accelerating test at 40°C and 75% RH demonstrated that drug release of pellets was not changed and drug degradation was less than 1%. Thus, a novel MCD process with MCC matrix was feasible and effective to get complete release without a lag time for the poorly water soluble drug, LVA, with high stability.

Atorvastatin: safety and tolerability

IMPORTANCE OF THE FIELD

Atorvastatin is the most widely used statin administered in a variety of settings, including primary and secondary prevention of cardiovascular events, in the elderly, in patients with chronic kidney disease and in diabetic patients. Therefore, the safety and tolerability of atorvastatin is of paramount importance.

AREAS COVERED IN THIS REVIEW

We searched MEDLINE for literature published between 1997 and 2010 on the safety and tolerability of atorvastatin. We retrieved data from randomized controlled trials, meta-analyses, post-marketing studies, reports to regulatory bodies and case reports of rare adverse events.

WHAT THE READER WILL GAIN

The reader will gain insight into the incidence, severity, prevention and management of the major adverse effects of atorvastatin (i.e., liver function abnormalities and muscle-related side effects) overall and in special populations.

TAKE HOME MESSAGE

The existing data suggest that atorvastatin is generally well tolerated across the range of its therapeutic dosage (10 - 80 mg/day).

Combination therapy of dyslipidemia

Clinical trials have demonstrated the benefit of low-density lipoprotein (LDL) cholesterol reduction and, with less robust evidence, reduction of triglyceride levels and increased high-density lipoprotein (HDL) cholesterol in the prevention of atherosclerotic cardiovascular disease. Although the statins are the cornerstone of lipid-lowering therapy, they may not be adequate to accomplish all of the changes in lipid and lipoprotein levels called for in current guidelines. Combinations of one or more lipid-modifying drugs in addition to lifestyle changes are now part of clinical guidelines and are being used extensively in practice. Clinicians need to be familiar with the individual drugs and how they interact. There is also a need for outcome data with combination therapy, especially for statin-fibrate and statin-niacin combinations. Several clinical trials are underway and should provide further evidence for the benefit of combination therapy of dyslipidemia. New drug classes have the potential to provide additive effects with currently available medications to provide substantial LDL reduction and increased HDL level that may lead to a substantial reduction in the burden of atherosclerotic vascular disease.

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

IMPORTANCE OF THE FIELD

Despite effective lowering of low-density lipoprotein cholesterol (LDL-C) with statin for prevention of cardiovascular adverse events, residual risk remains high due to low high-density lipoprotein cholesterol (HDL-C) levels in patients with mixed dyslipidemia. As a result, alternative treatment options to raise HDL-C are being investigated intensively. Currently, niacin is the most potent lipid lowering agent for raising HDL-C levels together with lowering of triglyceride and LDL-C. Previous clinical studies have demonstrated that niacin therapy significantly reduces the risk of cardiovascular events in high risk subjects. However, the clinical use of niacin is limited by its major adverse effect, cutaneous flushing. Although the use of extended-release (ER) formulation can reduce flushing, the tolerability and compliance of niacin remains suboptimal. A selective antagonist of prostaglandin D Type 1 receptor, laropiprant, has been investigated in a number of clinical studies and shown to be effective in reducing niacin-induced flushing. Despite the potential of laropiprant in reducing niacin-induced flushing, the long-term clinical efficacy and potential off-target side effects are not well studied. AREAS COVERED IN THIS REVIEWS: In this article, the pharmacological properties, clinical efficacy and future perspective of this combination therapy of simvastatin/ER niacin/laropiprant are reviewed.

WHAT THE READER WILL GAIN

Readers will understand both the mechanism and clinical effects of the combination therapy of simvastatin/ER niacin/laropiprant.

TAKE HOME MESSAGE

The triple combination therapy of simvastatin/ER niacin/laropiprant may reduce flushing side effects and facilitate a more comprehensive treatment for patients with mixed dyslipidemia.

Evidence-based guidelines for cardiovascular risk reduction: the safety and efficacy of high-dose statin therapy

Current clinical guidelines for management of low-density lipoprotein cholesterol (LDL-C) have evolved to reflect the findings of numerous randomized clinical trials and represent an important opportunity to effectively improve the cardiovascular (CV) risk profile of a wide range of patients. Implementation of guideline-recommended LDL-C management strategies facilitates the appropriate use of all available treatments, including lifestyle and dietary changes and pharmacotherapy. Where intensive lowering of LDL-C is required, suboptimal use of statins is a major contributor to the significant number of patients who remain at an unnecessarily increased risk of CV disease as a consequence of failing to reach their guideline-recommended LDL-C goals. This underuse may be explained by concerns over the safety and efficacy of high-dose statin regimens in certain populations. These issues are explored in the context of current, evidence-based clinical guidelines for LDL-C management and, through 3 hypothetical case studies, selection of appropriate starting doses of statins, and titration to a higher dose or switching to a more potent statin, to ensure that patients reach their individual LDL-C goals and reduce their overall CV risk, is also examined.

Managing diabetic dyslipidemia: beyond statin therapy

Cardiovascular disease is a significant cause of morbidity and mortality in patients with diabetes mellitus. The lipid profile of type 2 diabetes mellitus is characterized by increased triglycerides (TGs), decreased high-density lipoprotein cholesterol (HDL-C), increased very low density lipoproteins (VLDLs), and small, dense low-density lipoprotein particles, the combination of which is highly atherogenic. In diabetic patients, current treatment guidelines target low-density lipoprotein cholesterol (LDL-C) <or= 100 mg/dL with statins. In patients with elevated TGs, non-HDL-C is considered a secondary target of therapy. Despite the use of statin therapy in diabetes, a significant number of fatal and nonfatal coronary heart disease (CHD) events still occur, indicating the need to target other modifiable risk factors for CHD, including high TGs and low HDL-C.

The safety of niacin in the US Food and Drug Administration adverse event reporting database

Of currently approved drugs, niacin is the most effective in raising high-density lipoprotein cholesterol levels, either as monotherapy or in combination with other agents. The US Food and Drug Administration's (FDA) Adverse Event Reporting System provides 1 mechanism to evaluate the safety of niacin as it is used in common clinical practice. In this report, the authors review recent analyses of adverse events reported to the FDA demonstrating that the extended-release formulation of niacin (niacin-ER) has a significantly better safety profile compared with other niacin formulations and compares favorably with other commonly used lipid-altering drugs, including 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) and fibrates. In addition, analyses of FDA adverse event reports of the pill combining lovastatin and niacin-ER suggest that the safety of combination therapy with niacin-ER and a statin is comparable with the safety of each of the drugs alone. These analyses should encourage the use of niacin-ER in patients at high risk for cardiovascular disease, as recommended by current national guidelines for cardiovascular prevention.

Neuromuscular complications of statins

Statins, 3-hydroxy-3-methlglutaryl coenzyme A reductase inhibitors, are commonly prescribed for patients who have hyperlipidemia. Statins were first approved in 1987. Statin therapy is well documented to reduce serum low-density lipoprotein levels, incidence of cardiovascular events, and mortality. Although statin therapy is well tolerated, serious adverse affects have been reported, including neuromuscular and hepatic complications. Myopathy is particularly concerning because of the potential for rhabdomyolysis and death. Recently, peripheral neuropathy also has been identified as a possible complication. The incidence of neuromuscular complications is expected to increase with the increased number of people using statin therapy. Clinicians should be aware of the potential neuromuscular complications. This article reviews epidemiology, possible mechanisms, risk factors, and management of statin-associated neuromuscular complications.

Relative safety of gemfibrozil and fenofibrate in the absence of concomitant cerivastatin use

Previous analyses of fibrate safety may have been driven by a higher propensity for gemfibrozil to interact with cerivastatin, which is currently off the market because of safety concerns. We reviewed gemfibrozil- and fenofibrate-associated adverse event reports (AERs) submitted to the US Food and Drug Administration over a 5-year period. To control for cerivastatin's impact on fibrate-associated AERs, reports with concomitant cerivastatin use were excluded. Rates per million prescriptions were calculated for all AERs, serious AERs, rhabdomyolysis AERs, muscle-related AERs without rhabdomyolysis, and liver AERs. The rates of all AERs (odds ratio [OR] 0.76, 95% confidence interval [CI] 0.69 to 0.83), serious AERs (OR 0.72, 95% CI 0.65 to 0.81), and liver AERs (OR 0.37, 95% CI 0.28 to 0.50) were significantly lower for gemfibrozil compared with fenofibrate (p <0.001 for each). In contrast, rates of rhabdomyolysis AERs (OR 2.67, 95% CI 2.11 to 3.39, p <0.001) and muscle-related AERs without rhabdomyolysis (OR 1.36, 95% CI 1.12 to 1.71, p = 0.002) were significantly higher for gemfibrozil compared with fenofibrate. In conclusion, the safety profiles of fibrates differ, with a higher rate of liver-related AERs associated with fenofibrate and a higher rate of muscle-related AERs associated with gemfibrozil. Rates of all AERs and serious AERs were higher with fenofibrate, but well within the range observed with commonly used lipid-altering medications.

Present-day uses of niacin: effects on lipid and non-lipid parameters

Existing guidelines for the prevention and treatment of coronary artery disease focus on lowering low-density lipoprotein cholesterol (LDL-C) as the primary lipid target. However, there has been increasing interest in raising high-density lipoprotein cholesterol (HDL-C) due to strong evidence linking low HDL-C levels with an increased risk of atherosclerosis. Raising HDL-C levels with lifestyle changes and pharmacologic interventions appear to reduce the risk of coronary artery disease beyond that of lowering LDL-C alone. Niacin has a substantial HDL-C raising effect, and also may beneficially alter total cholesterol, LDL-C and triglyceride levels. Niacin also exhibits antioxidant, anti-inflammatory and other beneficial effects on atherosclerosis. Niacin is safe and effective to use in women, in patients with diabetes mellitus and/or metabolic syndrome, and when used in combination with statins. Niacin has the promise of being a powerful pharmacologic agent in the fight against atherosclerotic disease, although additional clinical studies are required to examine this further.

Simvastatin: present and future perspectives

Simvastatin is lipophilic statin with a short half-life that is primarily metabolized by CYP450 3A4. At doses of 5 - 80 mg, simvastatin lowers LDL cholesterol by 25 - 50%. Simvastatin has been shown to reduce the risk of cardiovascular disease by 35% and overall mortality by up to 30% over 5 years. The recommended starting dose of simvastatin 40 mg is approved as a lipid-lowering agent and for all high-risk patients, including those with cardiovascular disease and diabetes, regardless of the baseline LDL level. Simvastatin dose should be adjusted in those receiving CYP3A4 inhibitors, gemfibrozil, or ciclosporin, amiodarone, or in those with severe renal insufficiency. Coformulation of simvastatin with ezetimibe is now available, and coformulation with extended release niacin is under development.

Niacin in cardiovascular prevention: mechanisms, efficacy, and safety

PURPOSE OF REVIEW

This review describes niacin's mechanism of action, efficacy in cardiovascular prevention, and safety.

RECENT FINDINGS

A G-protein-coupled receptor [GPR109A/HM74A, mouse PUMA-G (protein upregulated in macrophages by interferon-gamma)] was found to mediate the antilipolytic effect of niacin via inhibition of adenylyl cyclase in adipocytes. The same receptor in skin Langerhans cells mediates the common flushing side effect. The endogenous ligand for the receptor may be beta-hydroxybutyrate. Among nine controlled clinical trials using niacin, mostly combined with other drugs, statistically significant positive impact on clinical or anatomic cardiovascular end-points was found in seven, which represents a remarkably consistent record of benefit. Although niacin induces insulin resistance, deterioration of glycemic control in diabetes is usually minor, and there is no evidence of increased incidence of new onset diabetes. Hepatic toxicity is common with higher doses of sustained-release niacin but rare with immediate-release and extended-release niacin at doses up to 2000 mg/day. Extended-release and immediate-release niacin do not substantially potentiate myopathic effects when given in combination with statins.

SUMMARY

Recently developed understanding of the mechanisms, efficacy, and safety of niacin, along with progress in reducing the chief side effect of flushing, should enhance the use of this valuable agent for cardiovascular prevention.