Overview of niacin formulations: differences in pharmacokinetics, efficacy, and safety

The pharmacokinetics, efficacy, and safety of niacin and its various formulations are discussed. Niacin has been used for decades for the treatment of dyslipidemia because of its favorable effects on all lipoprotein parameters. Niacin significantly increases high-density lipoprotein cholesterol (HDL-C) more than any other available agent and reduces total cholesterol, low-density lipoprotein cholesterol (LDL-C), lipoprotein (a), and triglycerides. Niacin is currently available in immediate-release (IR), sustained-release (SR), and extended-release (ER) formulations that differ in their dissolution, pharmacokinetic, efficacy, and safety profiles. Important drawbacks to niacin therapy such as cutaneous flushing, associated with IR niacin, and hepatotoxicity, associated with SR niacin, have historically limited its use. The adverse effect profiles of the different niacin formulations can be explained by differences in their dissolution and absorption rates and metabolic disposition, which result in production of metabolites associated with the respective adverse effects. The ER niacin formulation, with an intermediate dissolution rate between the dissolution rates of IR and SR niacin, demonstrates reduced rates of cutaneous flushing compared with IR niacin and hepatotoxic effects compared with SR niacin. Pharmacists need to be familiar with the pharmacokinetics, efficacy, and safety of available niacin formulations so that they can optimally educate both patients and health care providers on the differences among niacin formulations, counsel on the proper selection of a niacin product, and provide strategies for improving tolerance and adherence to therapy.