Learning & education: Vitamin B3
Nicotinic acid and nicotinamide are different forms of vitamin B3 found in food. These compounds have identical vitamin activity; however, their pharmacological profiles differ. Indeed, nicotinamide has an amide group, notably absent in nicotinic acid, which confers different therapeutic and side effects. Depending on the country, nicotinic acid and nicotinamide are referred to as niacin and niacinamide, respectively.
Niacin exists in different forms, comprising nicotinic acid, nicotinamide, and nicotinamide riboside (NR). All of these compounds have essential roles in metabolism and cellular respiration. At the blood-brain barrier, nicotinamide is rapidly transferred across the cerebral capillaries in a bidirectional manner by a very low-affinity, high-capacity facilitated diffusion system.