Nicotinamide Protects Against Diet-Induced Body Weight Gain, Increases Energy Expenditure, and Induces White Adipose Tissue Beiging.

SCOPE: Interventions that boost NAD+ availability are of potential therapeutic interest for obesity treatment. The potential of nicotinamide (NAM), the amide form of vitamin B3 and a physiological precursor of nicotinamide adenine dinucleotide (NAD)+ , in preventing weight gain has not previously been studied in vivo. Other NAD+ precursors have been shown to decrease weight gain; however, their impact on adipose tissue is not addressed. METHODS AND RESULTS: Two doses of NAM (high dose: 1% and low dose: 0.25%) are given by drinking water to C57BL/6J male mice, starting at the same time as the high-fat diet feeding. NAM supplementation protects against diet-induced obesity by augmenting global body energy expenditure in C57BL/6J male mice. The manipulation markedly alters adipose morphology and metabolism, particularly in inguinal (i) white adipose tissue (iWAT). An increased number of brown and beige adipocyte clusters, protein abundance of uncoupling protein 1 (UCP1), mitochondrial activity, adipose NAD+ , and phosphorylated AMP-activated protein kinase (P-AMPK) levels are observed in the iWAT of treated mice. Notably, a significant improvement in hepatic steatosis, inflammation, and glucose tolerance is also observed in NAM high-dose treated mice. CONCLUSION: NAM influences whole-body energy expenditure by driving changes in the adipose phenotype. Thus, NAM is an attractive potential treatment for preventing obesity and associated complications.

Possible Adverse Effects of High-Dose Nicotinamide: Mechanisms and Safety Assessment.

Nicotinamide (NAM) at doses far above those recommended for vitamins is suggested to be effective against a wide spectrum of diseases and conditions, including neurological dysfunctions, depression and other psychological disorders, and inflammatory diseases. Recent increases in public awareness on possible pro-longevity effects of nicotinamide adenine dinucleotide (NAD+) precursors have caused further growth of NAM consumption not only for clinical treatments, but also as a dietary supplement, raising concerns on the safety of its long-term use. However, possible adverse effects and their mechanisms are poorly understood. High-level NAM administration can exert negative effects through multiple routes. For example, NAM by itself inhibits poly(ADP-ribose) polymerases (PARPs), which protect genome integrity. Elevation of the NAD+ pool alters cellular energy metabolism. Meanwhile, high-level NAM alters cellular methyl metabolism and affects methylation of DNA and proteins, leading to changes in cellular transcriptome and proteome. Also, methyl metabolites of NAM, namely methylnicotinamide, are predicted to play roles in certain diseases and conditions. In this review, a collective literature search was performed to provide a comprehensive list of possible adverse effects of NAM and to provide understanding of their underlying mechanisms and assessment of the raised safety concerns. Our review assures safety in current usage level of NAM, but also finds potential risks for epigenetic alterations associated with chronic use of NAM at high doses. It also suggests directions of the future studies to ensure safer application of NAM.

Effects of Nicotinamide and Lanthanum Carbonate on Serum Phosphate and Fibroblast Growth Factor-23 in CKD: The COMBINE Trial.

BACKGROUND: Higher serum phosphate and fibroblast growth factor-23 (FGF23) levels may be modifiable to prevent cardiovascular disease in CKD. Short-term studies have reported modest efficacy in phosphate and FGF23 reduction with intestinal phosphate binders in CKD. METHODS: To investigate effects of lanthanum carbonate (LC; a phosphate binder) and/or nicotinamide (NAM; an inhibitor of active intestinal phosphate transport) on serum phosphate and FGF23 in stage 3b/4 CKD, we conducted a randomized trial among individuals with eGFR 20-45 ml/min per 1.73 m2 to NAM (750 mg twice daily) plus LC (1000 mg thrice daily), NAM plus LC placebo, LC plus NAM placebo, or double placebo for 12 months. Dual primary end points were change from baseline in serum phosphate and intact FGF23 concentrations. RESULTS: Mean eGFR for the 205 participants was 32ml/min per 1.73 m2. At baseline, serum phosphate was 3.7 mg/dl and median FGF23 was 99 pg/ml (10th, 90th percentiles: 59, 205). Mean rates of change in phosphate increased slightly over 12 months in all groups and did not differ significantly across arms. Similarly, percent changes in FGF23 per 12 months increased for all arms except LC plus placebo, and did not differ significantly across arms. Gastrointestinal symptoms limited adherence. Adverse events rates were similar across arms. CONCLUSIONS: LC and/or NAM treatment did not significantly lower serum phosphate or FGF23 in stage 3b/4 CKD over 12 months. Although these agents appeared safe, intestinal symptoms limited adherence. Reducing phosphate and FGF23 in nondialysis CKD will require new approaches.

Treatment of hepatocellular carcinoma: a cost analysis of yttrium-90 transarterial radioembolization versus sorafenib.

AIM: The aim was to evaluate cost-effectiveness of yttrium-90 transarterial radioembolization (TARE) in comparison to sorafenib treatment. PATIENTS & METHODS: A single-center, retrospective, observational study was performed, 166 patients with intermediate-/advanced-stage hepatocellular carcinoma were treated with sorafenib and 19 with TARE. The patients out of the sorafenib group matching the inclusion criteria for TARE, were reassigned to a subgroup SOR3. RESULTS: Mean costs for SOR3 patients amounted to €27,992 per patient, instead for TARE treatment, mean expense per patient was €17,761 (p = 0.028). Overall survival was similar between the two groups, while midterm survival rates (p = 0.012) were significantly higher with TARE treatment. CONCLUSION: TARE causes significantly lower treatment costs than sorafenib with better outcome in midterm survival.

Real-world costs and outcomes in metastatic renal cell carcinoma patients treated with targeted therapies: a cohort study from the French health insurance database.

OBJECTIVES: The objective of this study was to describe treatment patterns, survival, healthcare use and costs in patients with metastatic renal cell carcinoma (mRCC) in a real-world setting. RESEARCH DESIGN AND METHODS: We used the National Health Insurance (NHI) claims database for the Ile-de-France region to perform a retrospective cohort analysis of patients with mRCC treated by a first-line targeted therapy. Treatment naïve patients were identified combining the 10th revision of the International Classification of Diseases (ICD-10) codes (C64 & C77-C79) and a first prescription of targeted therapies. Descriptive analyses were performed on treatment patterns and patients' characteristics. Progression free survival (PFS) and overall survival (OS) were determined using Kaplan-Meier actuarial survival analysis. All healthcare resource use and costs were estimated on a per patient per month (PPPM) basis (€2016). RESULTS: A total of 327 treatment naïve patients with mRCC were included. Median follow-up was 13.4 months. Sunitinib accounted for 73% of first-line treatments. The most frequently observed treatment sequence for the first two lines was sunitinib-everolimus (16%; n = 137) and for the first three lines sunitinib-everolimus-axitinib (20%; n = 49). First-line PFS for sunitinib, everolimus, pazopanib, sorafenib and other was 8.7, 6.2, 10.7, 5.7 and 11.2 months, respectively. Median OS for patients treated by first-line sunitinib, everolimus, pazopanib, sorafenib and other was respectively 14.7, 8.1, 21.1, 8.9 and 14.0 months. From the NHI's perspective, the mean PPPM was €5546. The average PPPM in pre-progression was €5597 compared to €5541 beyond progression of the disease. Oral targeted therapies accounted for 53% of the total PPPM. CONCLUSION: This descriptive study showed that the economic burden of mRCC is substantial with oral targeted therapies accounting for 53% of the PPPM. OS and PFS in real life are poorer than observed in clinical trials.

[Meta-analytic assessment of parenteral cytoflavin effectiveness in different neurologic disorders]. / Metaanaliticheskaia otsenka klinicheskoi éffektivnosti tsitoflavina pri nevrologicheskikh zabolevaniiakh.

AIM: To carry out an integral quantitative assessment of the clinical efficacy of parenteral use of cytoflavin in treatment of patients with CNS disorders based on the systemic selection of published controlled clinical trials and their meta-analysis. MATERIAL AND METHODS: Twenty-one high evidence-based studies on the efficacy of parenteral use of cytoflavin in different CNS disorders (4314 patients) have been analyzed. Comparisons with basic treatment groups were undertaken to clarify the drug clinical effects adjusted for heterogeneity and variability of response parameters. RESULTS AND CONCLUSION: An analysis of formalized efficacy indicators (increase in the absolute and relative value, odds ratio (OR) etc.) has demonstrated the advantages of cytoflavin. Group combination has increased the statistical power of the meta-analysis. Two models with fixed (Mantel-Haenszel amendment) and random effects were used. All the estimation protocols in different clinical groups of patients with neurologic diseases provided similar results and confirmed the stability of calculated values irrespective of heterogeneity of data arrays. OR of positive outcomes in neuropathologies treated with cytoflavin was 3,02 with χ2 heterogeneity 427,3 and p = 0,000…, I2= 85,7% (82%; 88%).

Sorafenib Effectiveness in Advanced Hepatocellular Carcinoma.

BACKGROUND: Phase III trials show sorafenib improves survival in advanced hepatocellular carcinoma (HCC). Because of narrow trial eligibility, results may not be generalizable to a broader HCC population. We sought to evaluate the effectiveness of initial sorafenib versus no treatment among Medicare beneficiaries with advanced HCC. MATERIALS AND METHODS: Patients with advanced HCC diagnosed from 2008 to 2011 were identified from the Surveillance, Epidemiology, and End Results-Medicare database. Eligible patients received initial sorafenib or no therapy and were covered by Medicare parts A, B, and D. Sorafenib use and outcomes were described in this population. Using a propensity score (PS)-matched sample, we compared the effectiveness of sorafenib versus no treatment by Cox proportional hazards and binomial regression, using a landmark requiring all patients to survive ≥60 days after diagnosis. RESULTS: Of 1,532 patients, 27% received initial sorafenib. Median duration of sorafenib use was 60 days (interquartile range [IQR], 30-107 days), and median survival from first prescription was 3 months (IQR, 1-8 months). In the PS-matched cohort, median survival was 3 months from the 60-day landmark in sorafenib-treated (n = 223) and 2 months in untreated (n = 223) patients (adjusted hazard ratio, 0.95 [95% confidence interval (CI), 0.78-1.16]). Sorafenib was associated with a nonsignificant reduction in mortality at 3 months (44% versus 51%; adjusted risk ratio, 0.88 [95% CI, 0.72-1.07]), but no reduction thereafter. CONCLUSION: Survival after sorafenib initiation in newly diagnosed Medicare beneficiaries with HCC is exceptionally short, suggesting trial results are not generalizable to all HCC patients. The downsides of sorafenib use-high drug-related symptom burden and high drug cost-must be considered in light of this minimal benefit. IMPLICATIONS FOR PRACTICE: The findings of a median survival of only 3 months in Medicare beneficiaries with HCC prescribed sorafenib as first-line therapy highlight the questionable value of sorafenib in this population. Patients should be cautioned that outside of the narrow confines of randomized trials, their life expectancy may be very short, and any benefit of sorafenib is likely to be quite small. Given that sorafenib causes considerable adverse effects and offers no symptom palliation, supportive care should be discussed as a reasonable alternative to sorafenib, particularly for patients who have a poor performance status or advanced cirrhosis.

Trends and Patterns of Hepatocellular Carcinoma Treatment in Korea.

Multiple therapeutic modalities are available for hepatocellular carcinoma (HCC) treatment. We aimed to evaluate the trends for HCC treatment in Korea. Recent trends and patterns in treatment modalities were assessed in HCC patients who first registered for the Health Insurance Review Assessment Service between 2008 and 2012. From 2009 to 2012, 57,690 patients were diagnosed with HCC. Transcatheter arterial chemoembolization (TACE) was the most common treatment modality for initial treatment. Curative treatment modalities like hepatic resection, liver transplantation, and local ablation therapy increased gradually. The 3 most common treatment modalities (hepatic resection, local ablation therapy, TACE) used after initial treatment in 2009 were studied. Following initial hepatic resection, 44.5% of patients required re-treatment. TACE was the most common modality (in 48.3% of cases), while 15.0% of patients received local ablation therapy. After local ablation therapy, 55.4% of patients were re-treated, wherein 45.0% of patients received TACE and 31.5% received local ablation therapy. Following initial TACE, 73.9% patients were re-treated, most commonly with TACE (57.7%) followed by local ablation therapy (12.8%). While there were no significant differences between the initial and re-treatment modalities, various multiple treatments followed the initial treatment. The treatment modalities were interchangeable.

Volumetric assessment of tumour response using functional MR imaging in patients with hepatocellular carcinoma treated with a combination of doxorubicin-eluting beads and sorafenib.

OBJECTIVE: To prospectively assess treatment response using volumetric functional magnetic resonance imaging (MRI) metrics in patients with hepatocellular carcinoma (HCC) treated with the combination of doxorubicin-eluting bead-transarterial chemoembolization (DEB TACE) and sorafenib. METHODS: A single center study enrolled 41 patients treated with systemic sorafenib, 400 mg twice a day, combined with DEB TACE. All patients had a pre-treatment and 3-4 week post-treatment MRI. Anatomic response criteria (RECIST, mRECIST and EASL) and volumetric functional response (ADC, enhancement) were assessed. Statistical analyses included paired Student's t-test, Kaplan-Meier curves, Cohen's Kappa, and multivariate cox proportional hazard model. RESULTS: Median tumour size by RECIST remained unchanged post-treatment (8.3 ± 4.1 cm vs. 8.1 ± 4.3 cm, p = 0.44). There was no significant survival difference for early response by RECIST (p = 0.93). EASL and mRECIST could not be analyzed in 12 patients. Volumetric ADC increased significantly (1.32 × 10(-3) mm(2)/sec to 1.60 × 10(-3) mm(2)/sec, p < 0.001), and volumetric enhancement decreased significantly in HAP (38.2% to 17.6%, p < 0.001) and PVP (76.6% to 41.2%, p < 0.005). Patients who demonstrated ≥ 65% decrease PVP enhancement had significantly improved overall survival compared to non-responders (p < 0.005). CONCLUSION: Volumetric PVP enhancement was demonstrated to be significantly correlated with survival in the combination of DEB TACE and sorafenib for patients with HCC, enabling precise stratification of responders and non-responders. KEY POINTS: • PVP enhancement is significantly correlated with survival in responders (p < 0.005). • There was no significant survival difference for early response using RECIST (p = 0.93). • mRECIST or EASL could not assess tumour response in 29% of patients.

[The assessment of the effects of cytoflavin and cardioxipin on the emotional status of rats with dyslipidemia].

OBJECTIVE: To compare the effects of cytoflavin and cardioxipin on the emotional status of rats with experimental disturbance of lipid metabolism using the uplifted cruciform labyrinth method. MATERIAL AND METHODS: The disturbance of lipid metabolism was induced by the introduction of exogenic cholesterol-in -oil emulsion in dosage 40 mg /kg of body mass during 20 days. Pharmacological treatment was performed in the 11th day. The drugs were injected intraperitoneally during 10 days: cytoflavin in dose 1,75 ml/ kg (175 mg/kg with succinic acid), cardioxipin in dose 52,5 mg/kg. RESULTS AND CONCLUSION: Cytoflavin and cardioxipin caused the positive changes in the parameters of emotional status of rats in conditions of experimental dyslipidemia.

Drug safety evaluation of sorafenib for treatment of solid tumors: consequences for the risk assessment and management of cancer patients.

INTRODUCTION: Sorafenib is a multi-tyrosine kinase inhibitor (TKI). Considerable clinical experience has been accumulated since its first Phase III clinical trial in metastatic renal cancer patients in 2007. The management of its early acute toxicity in fit patients is well known. The management of prolonged treatment becomes the new challenge. AREAS COVERED: Using sorafenib as a key word for PubMed search, we review preclinical and clinical data and discuss the pharmacokinetics and pharmacodynamics of sorafenib, its acute and cumulative toxicities and their consequences for patient management. EXPERT OPINION: The systematic multi-disciplinary risk assessment of cancer patients prior to TKI initiation reduces the risks of acute and late toxicity, especially drug-drug interactions and arterial risks. Sarcopenia is now identified as a major risk of severe toxicity. The very diverse clinical pictures of cumulative toxicity must be known. The monitoring of sorafenib systemic exposure is helpful especially in elderly patients. Moreover, at disease progression, it allows distinguishing between underexposure to sorafenib and truly acquired resistance to the drug. The optimal use of sorafenib should allow improving the reported results of flat-dose. Finally, most of this knowledge could be used for the development and optimal use of the other TKIs.

Predictors of non-adherence to systemic oral therapy for advanced hepatocellular carcinoma.

OBJECTIVES: With increasing use and cost of oral oncology medications, patient non-adherence with oral therapy is of concern. This study evaluated non-adherence among patients receiving first-line oral therapy for hepatocellular carcinoma (HCC). METHODS: This retrospective study used the employer-based MarketScan medical and pharmacy claims database (2005-2011) to identify adult patients with two or more diagnoses of HCC (ICD-9 155), and two or more filled prescriptions for sorafenib. Additional eligibility requirements were not having other previous cancers and a 4 month wash-out period prior to the index sorafenib date. Adherence was assessed using a modified proportion of days covered (PDC) measure with patient-specific sorafenib exposure from index date to treatment discontinuation. Non-adherence was categorized as PDC <85% (base case), with sensitivity analyses using an 80% cut-off and allowance for physician-directed therapy gaps. Logistic regression models were estimated to identify predictors of non-adherence. RESULTS: A total of 1127 patients (median age = 61.0 years; 78.4% male) met eligibility criteria. Median duration of enrollment was 223 days and median sorafenib exposure was 121 days. Between 21.1% (PDC < 0.80) and 28.0% (PDC < 0.85) of patients were non-adherent. Higher age (p = 0.022), number of baseline medications (p = 0.003) and number of baseline comorbidities (p = 0.002) were associated with lower non-adherence, while prior procedures were associated with greater non-adherence (p = 0.002). LIMITATIONS: In this study using billing claims data, we were unable to evaluate patient severity in terms of clinical characteristics such as the Child-Pugh score. Similarly, we could not assess clinical outcomes such as tumor response, radiological progression or overall survival, although median duration of sorafenib exposure and duration of health plan enrollment respectively were found to be good proxies. CONCLUSIONS: Using a modified PDC approach, 22-29% of patients were non-adherent. Identified predictors of non-adherence in HCC should be assessed for newly emerging oral therapies, and may be used to guide patient education and other adherence-enhancing initiatives.

Assessment of nutritional status in cancer--the relationship between body composition and pharmacokinetics.

Several nutritional assessment tools have been used in oncology settings to monitor nutritional status and its associated prognostic significance. Body composition is fundamental for the assessment of nutritional status. Recently, the use of accurate and precise body composition tools has significantly added to the value of nutritional assessment in this clinical setting. Computerized tomography (CT) is an example of a technique which provides state-of-the-art assessment of body composition. With use of CT images, a great variability in body composition of cancer patients has been identified even in people with identical body weight or body mass index. Severe muscle depletion (sarcopenia) has emerged as a prevalent body composition phenotype which is predictive of poor functional status, shorter time to tumor progression, shorter survival, and higher incidence of dose-limiting toxicity. Variability in body composition of cancer patients may be a source of disparities in the metabolism of cytotoxic agents. Future clinical trials investigating dose reductions in patients with sarcopenia and dose-escalating studies based on pre-treatment body composition assessment have the potential to alter cancer treatment paradigms.

In a 'real-world', clinic-based community setting, sorafenib dose of 400 mg/day is as effective as standard dose of 800 mg/day in patients with advanced hepatocellular carcimona, with better tolerance and similar survival.

BACKGROUND: Sorafenib, an oral multityrosine kinase inhibitor, has been approved for treatment of unresectable hepatocellular carcinoma (HCC). British Columbia (BC) was the first province in Canada to provide drug coverage for sorafenib. OBJECTIVE: To review the BC experience with sorafenib to assess its effectiveness and tolerance in a 'real-world' clinical setting. METHODS: A retrospective clinic chart review identified 99 patients referred to the BC Cancer Agency from 2008 to 2010 with a diagnosis of HCC who qualified for treatment with sorafenib. RESULTS: Therapy with sorafenib was initiated and continued at a reduced dosage of 400 mg/day in 66 of 99 patients, with 22 patients requiring further dose reduction. Full- and reduced-dose group patients had similar baseline characteristics, except for a higher proportion of female patients (P=0.02) and individuals with alcoholic liver disease (P=0.04) in the full-dose group. The incidence of any grade of adverse effects was higher in the full-dose group (94% versus 77% in the reduced-dose group; P=0.04). Dose reduction rates were significantly higher in the full-dose group, occurring in 66% versus 24% of reduced-dose group patients (P=0.001). The overall survival rates were similar between the two groups: 7.8 months versus 7.1 months in full- versus reduced-dose groups (P=0.14), as were radiological progression rates and alpha-fetoprotein levels. CONCLUSIONS: In a review of 99 patients in a 'real-world' community setting, a sorafenib dose of 400 mg/day was better tolerated and had similar efficacy compared with a sorafenib dose of 800 mg/day with respect to survival and outcomes.

[Assessment of multimodal effect of cytoflavin in the acute brain stroke in patients with metabolic syndrome].

Sixty patients were randomized to treatment with cytoflavin (n=30) or nootropil (n=30). Patients of the main group received cytoflavin along with standard treatment for correction of hemodynamics. The treatment scheme was as follows: intravenous injections during 10 days, tablets - from 11 to 35 days. The same scheme of treatment was used in the comparison group. The total duration was 35 days. Patients were assessed with NIHSS, the Rankin scale, the Barthel index, MMSE. MRI was used to verify ischemic lesions. The therapeutic efficacy of cytoflavin was significantly higher compared to nootropil in respect to the restoration of neurological functions and self-service abilities as well as to the reduction of cognitive deficit.

Assessment of hypolipidaemic activity of three thiazolidin-4-ones in mice given high-fat diet and fructose.

Three 4-thiazolidinones, two with nicotinamide (NAT1 and NAT2) and one with 4-chlorophenoxyacetamide (PAT1) side chains were evaluated for their hypolipidaemic, hypoglycaemic activity in Swiss albino mice fed a high-fat diet along with fructose administered in drinking water. NAT1 and PAT caused reduction of elevated triglycerides, cholesterol and glucose; NAT2 was effective only against triglycerides. Nicotinamide side chain might have contributed to the lipid lowering effect of both NAT1 and NAT2, but the bulky group of the latter could have affected proper binding to the receptor sites, making it ineffective against elevated cholesterol. On the other hand, the 4-chlorophenoxyacetamide side chain of PAT might have exerted powerful hypolipidaemic activity, despite the bulky substitution at C2. As antioxidants, NAT2 and PAT1 showed superior activity, compared to NAT1. The thiazolidinone ring might be responsible for the lipid lowering effect, which is however, modified by the type of substitutions at C2 and N of the ring. Detailed study is warranted to explain the mechanism of action of these compounds as also to make more potent ones.

Nicotinamide pharmacokinetics in humans and mice: a comparative assessment and the implications for radiotherapy.

Healthy human volunteers orally ingested escalating doses of up to 6 g nicotinamide in capsule form on an empty stomach. Some side-effects were seen although these were mild and transient. HPLC analysis of blood samples showed peak plasma levels, typically within 45 min after ingestion, which were linearly dependent on dose ingested. The elimination half-life and AUC were also found to increase with drug dose, although these increases were non-linear. Pharmacokinetic studies were also performed in female CDF1 mice with C3H mammary carcinomas grown in the right rear foot. Analysis of blood and tumour samples taken from mice injected i.p. with nicotinamide doses between 100-1000 mg/kg showed similar characteristics as the human data, although the elimination half-lives were not dose-dependent. The average peak plasma concentration of 160 micrograms/ml measured in humans after taking 6 g of nicotinamide was equivalent to that seen in mice after injecting 171 mg/kg. Using a regrowth delay assay the enhancement of radiation damage by nicotinamide in this mouse tumour was found to be independent of drug dose from 100-1000 mg/kg, resulting in a constant 1.3-fold increase in radiation response. Doses of nicotinamide that can be tolerated clinically should therefore produce adequate enhancements of radiation damage in human tumours.

Biochemical markers for assessment of niacin status in young men: urinary and blood levels of niacin metabolites.

Biochemical markers of niacin status were studied in healthy young men fed 6.1 to 32 niacin equivalents (NE) per day over an 11-wk period while residing in a metabolic unit. Methylated metabolites of niacin, N1-methylnicotinamide (NMN) and N1-methyl-2-pyridone-5-carboxamide (2-pyr), in urine and plasma were determined during periods of low (6.1 or 10.1 NE per day), adequate (19 NE per day = 1 RDA) and high (25 or 32 NE per day) niacin intakes and after small test doses of nicotinamide. Urine excretion of less than 1.2 mg/d of either NMN or 2-pyr was a reliable indicator of subjects receiving the lowest intake of 6.1 NE/d, but the NMN metabolite was a better marker of subjects ingesting 10.1 NE/d. The ratio of 2-pyr/NMN in urine was not as good a measure of the 6.1 NE/d intake as the individual metabolite excretions and was not responsive to the 10.1 NE/d intake. Plasma niacin metabolites were generally not as reliable as urinary metabolites for identifying subjects receiving low niacin intakes, however, values for plasma 2-pyr dropped quickly and were eventually nondetectable. After a 1 RDA oral dose of nicotinamide, increases in urine and plasma 2-pyr levels above pre-dose baseline values were significantly decreased in subjects receiving low, as compared to adequate, niacin intake. A leucine supplement had no effect on the rate of repletion of niacin-deficient subjects nor on the level of methylated niacin metabolites in urine or plasma.