Niacin is available in a number of different formulations according to the speed of drug release. The nomenclature is not standardized, and many names are used interchangeably, creating confusion. Formulations that differ in time of release may have different lipid effects and vary in their adverse reaction profiles. Studies comparing immediate-release with various time-release formulations illustrate these variations. Studies have found immediate-release and the intermediate, or extended-release, once-a-day, prescription form of niacin (i.e., Niaspan), to be essentially equivalent with respect to their efficacy in reducing triglycerides and increasing high-density lipoprotein cholesterol (HDL-C). However, there are fewer side effects and better compliance associated with the latter form.