The flavonoid luteolin inhibits niacin-induced flush

BACKGROUND AND PURPOSE: Sustained release niacin effectively lowers serum cholesterol, LDL and triglycerides, while raising HDL. However, 75% of patients experience cutaneous warmth and itching known as flush, leading to discontinuation. Acetylsalicylic acid (aspirin) reduces this flush only by about 30%, presumably through decreasing prostaglandin D2 (PGD2). We investigated whether niacin-induced flush in a rat model involves PGD2 and 5-HT, and the effect of certain flavonoids. EXPERIMENTAL APPROACH: Three skin temperature measurements from each ear were recorded with an infrared pyrometer for each time point immediately before i.p. injection with either niacin or a flavonoid. The temperature was then measured every 10 min for 60 min. KEY RESULTS: Niacin (7.5 mg per rat, equivalent to a human dose of 1750 mg per 80 kg) maximally increased ear temperature to 1.9+/-0.2 degrees C at 45 min. Quercetin and luteolin (4.3 mg per rat; 1000 mg per human), administered i.p. 45 min prior to niacin, inhibited the niacin effect by 96 and 88%, respectively. Aspirin (1.22 mg per rat; 325 mg per human) inhibited the niacin effect by only 30%. Niacin almost doubled plasma PGD2 and 5-HT, but aspirin reduced only PGD2 by 86%. In contrast, luteolin inhibited both plasma PGD2 and 5-HT levels by 100 and 67%, respectively. CONCLUSIONS AND IMPLICATIONS. Niacin-induced skin temperature increase is associated with PGD2 and 5-HT elevations in rats; luteolin may be a better inhibitor of niacin-induced flush because it blocks the rise in both mediators.     

Niacin Toxicity Resulting from Urine Drug Test Evasion

Background: Niacin, a well-established agent for treating dyslipidemia, has been promoted on the Internet as a method for passing urine drug screening, although there are no data to support its use for this purpose. In a handful of cases, this practice has resulted in serious niacin toxicity. Objectives: The aim of this article is to describe a unique clinical presentation of niacin toxicity. Case Report: A 23-year-old previously healthy man presented to an Emergency Department with altered mental status, fever, acute renal failure, microangiopathic hemolytic anemia, thrombocytopenia, and coagulopathy. It was revealed that he had taken approximately 22.5 g of sustained-release niacin over the preceding 48 h in an attempt to pass a pre-employment urine drug screen. After a complicated hospital course that included mechanical ventilation for respiratory failure and hemodialysis for acute renal failure, the patient made a full recovery and was discharged 10 days after his initial presentation. Conclusion: After a massive niacin overdose, the young man in this case presented with a complex clinical picture that mimicked concurrent thrombotic thrombocytopenic purpura and disseminated intravascular coagulation. Although this patient was fortunate to make a full recovery, the case highlights the potential for multi-system toxicity with niacin overdose, and the potential for harm posed by medical misinformation on the Internet.     

Future of GPR109A agonists in the treatment of dyslipidaemia

Abnormal blood lipids are the major modifiable risk factor underlying the development of cardiovascular disease. Niacin has a profound ability to reduce low-density lipoprotein-C, very low-density lipoprotein-C and triglycerides and is the most effective pharmacological agent to increase high-density lipoprotein-C. Recently, the receptor for niacin, GPR109A, was discovered. GPR109A in the adipocyte mediates a niacin-induced inhibition of lipolysis, which could play a crucial part in its role as a lipid-modifying drug. GPR109A in epidermal Langerhans cells mediates flushing, an unwanted side effect of niacin therapy. For the past decade, the functions of GPR109A have been studied and full or partial agonists have been developed in an attempt to achieve the beneficial effects of niacin while avoiding the unwanted flushing side effect. This review presents what is known to date about GPR109A biology and function and the future of GPR109A as a pharmacological target.     

反刍动物烟酸营养研究进展

烟酸在反刍动物能量、蛋白质、脂肪代谢中发挥重要作用.本文对反刍动物瘤胃中烟酸的来源、分布、吸收及合成影响因素的相关主要研究进行了回顾,并综述了近年国内外烟酸对反刍动物营养代谢影响的主要研究进展,最后对今后的研究方向进行了展望,以期为反刍动物生产和研究提供参考.     

The Emergent Curriculum

The emergent curriculum model, which enables learners to assist in curriculum construction, was used in a nutrition education program with senior citizens in a Title III-C program in New York City. Topics selected for discussion in the seven one-hour-per-week sessions were based on intake interview data, analysis of questions asked during sessions and direct solicitation. Techniques of participant observation for data collection and qualitative analysis were used. The curriculum model was found to be particularly useful because it allowed for personalization in this notably heterogeneous population. Fulfillment of individual learning needs was the major criterion in evaluating success.     

Statins,fibrates, nicotinic acid,cholesterol absorption inhibitors,anion‐exchange resins,omega‐3 fatty acids: which drugs for which patients?

Classes of lipid lowering drugs differ strongly with respect to the types of lipids or lipoproteins they predominantly affect. Statins inhibit the de-novo synthesis of cholesterol. Consequently, the liver produces less VLDL, and the serum concentration primarily of LDL cholesterol (but, to a lesser extent, also of triglycerides) is lowered. Further, statins somewhat increase HDL cholesterol. There is abundant evidence that statins lower the rate of cardiovascular events. Cardiovascular risk reduction is the better, the lower the LDL cholesterol values achieved with statin therapy are. Some evidence is available that anion exchange resins which also decrease LDL cholesterol decrease vascular risk, too. This is not the case for the ezetimibe, which strongly lowers LDL cholesterol: its potential to decrease vascular risk remains to be proven. In contrast evidence for cardiovascular risk reduction through the mainly triglyceride lowering fibrates as well as for niacin is available. Niacin is the most potent HDL increasing drug currently available and besides increasing HDL cholesterol efficaciously lowers triglycerides and LDL cholesterol. Large ongoing trials address the decisive question whether treatment with fibrates and niacin provides additional cardiovascular risk reduction when given in addition to statin treatment.     

Association between Dietary Niacin Intake and Migraine among American Adults: National Health and Nutrition Examination Survey

Migraine is related to brain energy deficiency. Niacin is a required coenzyme in mitochondrial energy metabolism. However, the relationship between dietary niacin and migraines remains uncertain. We aimed to evaluate the relationship between dietary niacin and migraine. This study used cross-sectional data from people over 20 years old who took part in the National Health and Nutrition Examination Survey between 1999 and 2004, collecting details on their severe headaches or migraines, dietary niacin intake, and several other essential variables. There were 10,246 participants, with 20.1% (2064/10,246) who experienced migraines. Compared with individuals with lower niacin consumption Q1 (≤12.3 mg/day), the adjusted OR values for dietary niacin intake and migraine in Q2 (12.4–18.3 mg/day), Q3 (18.4–26.2 mg/day), and Q4 (≥26.3 mg/day) were 0.83 (95% CI: 0.72–0.97, p = 0.019), 0.74 (95% CI: 0.63–0.87, p < 0.001), and 0.72 (95% CI: 0.58–0.88, p = 0.001), respectively. The association between dietary niacin intake and migraine exhibited an L-shaped curve (nonlinear, p = 0.011). The OR of developing migraine was 0.975 (95% CI: 0.956–0.994, p = 0.011) in participants with niacin intake < 21.0 mg/day. The link between dietary niacin intake and migraine in US adults is L-shaped, with an inflection point of roughly 21.0 mg/day.