Also found this:
But researchers emphasize that immediate-release niacin should remain as a treatment option for high cholesterol. "The point of our study is not that niacin should be avoided, but that the immediate-release preparation is the preferred form, and that medical supervision and evaluation are necessary for people taking this drug," said James McKenney, professor and chairman of the division of clinical pharmacy at the Medical College of Virginia.
It's especially important for people taking high doses of niacin to have regular liver function tests. These should be performed every few weeks when a patient is adjusting to a new dose, and after that can be cut back to once or twice a year, said Dr. McKenney.
"People should make sure that they stick with the same brand of niacin because side effects may vary from one manufacturer to the next," advised Mason Freeman, director of the Lipid Clinic at Massachusetts General Hospital.