OBJECTIVE:To test the safety, tolerance, and efficacy of extended-release niacin monotherapy on dyslipidemia in persons with chronic tetraplegia. DESIGN:Placebo-controlled, blinded, multicenter, randomized controlled trial. SETTING:Three spinal cord injury research/rehabilitation centers. PARTICIPANTS:Persons with chronic tetraplegia (N=54) and low plasma high-density lipoprotein cholesterol (HDL-C) levels. INTERVENTION:Extended-release niacin monotherapy (48 weeks; n=31) on a dose-titration schedule versus matched placebo (n=23). MAIN OUTCOME MEASURES:Safety was assessed by using percentages of treatment-emergent adverse events and increased levels of hepatic transaminases, uric acid, glycosylated hemoglobin, and fasting glucose. Tolerance was assessed by using participant reports for frequency and intensity of adverse effects of extended-release niacin. Primary effectiveness outcomes were fasting HDL-C level and plasma total cholesterol (TC)/HDL-C ratio. Secondary outcomes included plasma low-density lipoprotein cholesterol (LDL-C) and TC levels and LDL-C/HDL-C ratio. RESULTS:Significant increases in fasting HDL-C levels (24.5%) were accompanied by decreases in TC/HDL-C and LDL-C/HDL-C ratios, LDL-C levels, and TC levels (all P<.05). No evidence of sustained hepatotoxicity or hyperglycemia was observed. Treatment-emergent withdrawals (12.9%) accompanied flushing (n=1), hypotension/presyncope (n=1), and diarrhea (n=2). One subject experienced transient hyperuricemia. Other drug-reported symptoms did not differ from those for placebo. CONCLUSIONS:Extended-release niacin monotherapy is safe, tolerated, and effective for most persons with chronic tetraplegia. Special precautions for changes in bowel habits and postadministration hypotension should be observed.