Mechanism of action of nicotinic acidniacin refers to nicotinic acid as well as nicotinamide which exerts it`s action by influencing metabolic reactions. it is converted in to coenzymes ncotinamide adenine dinucleotide (nad) and its phosphate ncotinamide adenine dinucleotide phosphate (nadp) involved in oxidation reduction reactions. these pyridine nucleotides act as hydrogen acceptors in the electron transport chain in tissue respiration, glycolysis, and fat synthesis. nicotinic acid in high doses has vasodilator effects and also improves lipid profile- reduces serum cholesterol, raises hdl level, lowers vldl, and ldl levels.indications for nicotinic acid1. pellagra 2. niacin deficiency 3. hartnup disease 4. hyperlipidaemia (only nicotinic acid 5. peripheral vascular diseases (only nicotinic acid)