We studied the release of nicotinic acid from a macromolecular pro-drug containing niacin bound to a polymeric support of dextran. Using a modified High-performance Liquid Chromatography (HPLC) method to provide an improved separation between nicotinic acid and its metabolites, we compared the plasma levels of nicotinic acid 24 h after administration of the pro-drug or a similar dose of unbound nicotinic acid to rats. Nicotinic acid exerts a number of pharmacological activities among which is the hypolipidemic effect. To determine the hypolipidemic effect of the pro-drug, we measured the triglyceride levels and examined the correlation with the plasma levels of nicotinic acid.Starting 6 h after administration of the pro-drug, the plasma levels of nicotinic acid were high enough to cause a decrease in the triglyceride level. These results suggest that nicotinic acid was gradually released from the polymeric support, leading to the sustained presence of the active substance and, therefore, a reduction in the level of triglycerides.