Metabolic Effects of an 8 Week Niaspan Treatment in Patients With Abdominal Obesity and Mixed Dyslipidemia
Lead SponsorCentre de Recherche en Nutrition Humaine Rhone-Alpe
StatusCompleted No Results Posted
Nicotinic acid (Niacin) has been used for many years for the treatment of dyslipidemia. Indeed Niacin decreases triglycerides (TG) and low density lipoprotein cholesterol (LDL-c) but more importantly increases high density lipoprotein cholesterol (HDL-c). Although the drug has been used for so long, its precise mechanism of action remains elusive. The aim of this study was to characterise the metabolic changes induced by 8 week treatment with Niacin in dyslipidemic, overweight patients. The importance of the inhibition of lipolysis on the overall lipid effects of niacin will be studied. In order to get a very comprehensive view of all metabolic activities of niacin, this study will investigate the potential effects of niacin on Glucose metabolism, lipid and lipoprotein turnover, quantitative changes in lipoproteins and key enzymes involved in lipid metabolism.
24 patients will be included in a double blind placebo controlled cross-over 8 week study comparing placebo to Niaspan (a long release formulation of niacin). In order to prevent any drop out linked to the flushing side effect of niacin, patient will take aspirin (300mg) prior to treatment throughout the study duration. The study will include at start and end of each arm, a full lipoproteins quantification as well as a measure of enzymes involved in lipid metabolism. On day 42 and 56 of each period, after an administration of either placebo or 500mg of immediate release niacin respectively, changes in plasma free fatty acid levels will be measured for 8hours in order to assess potential loss of activity of niacin over time upon chronic treatment with niaspan. Half of the patient will have an exploration of their glucose metabolism using hyperinsulinic clamp technique, whereas in the other half a metabolic turnover study using stable isotopes will focus on their lipoproteins, triglycerides and cholesterol handling. These explorations will be done at the end of each treatment period.
Voluntary men with mixed dyslipidemia and abdominal obesity will receive extended release nicotinic acid. The dose of niaspan will be up-titrated for 3 weeks starting at 500 mg/d in order to reach 2g/d at start of week 4 dose which will be continued until the end of week 8. After a wash-out period of 3 weeks, they will receive placebo for 8 weeks. According to their randomization arm, subjects will receive either in first place placebo followed by extended release nicotinic acid or the opposite.
Inclusion Criteria: Waist circumference > 94cm Triglyceride concentration between 150mg/dL and 400mg/dL HDL-c < 60mg/dL Body mass index: 27 to 35 kg/m² Exclusion Criteria: cancer diabetes mellitus hepatic, renal or digestive disorder hypertension chronic medical treatment interfering on lipids parameters