|
Niacinamide (nicotinamide) is one of the two principal forms of
the B-complex vitamin niacin (see Niacin). The term niacin is used
as a collective term to refer to both nicotinamide and nicotinic
acid, the other principal form of niacin, or the term is used
synonymously with nicotinic acid. Nicotinamide and nicotinic acid
have identical vitamin activities, but they have very different
pharmacological activities.
Nicotinamide, via its major
metabolite NAD++ (nicotinamide adenine dinucleotide), is involved in
a wide range of biological processes including the production of
energy, the synthesis of fatty acids, cholesterol and steroids,
signal transduction, and the maintenance of the integrity of the
genome. Nicotinic acid, in pharmacological doses, is used as an
antihyperlipidemic agent. It also causes vasodilatation of cutaneous
blood vessels resulting in the so-called niacin flush. Nicotinamide
in pharmacological doses does not have antihyperlipidemic activity,
nor does it cause a niacin-flush. There is evidence, however, that
pharmacological doses of nicotinamide may prevent type 1 diabetes
mellitus. Pyrazinamide, an important drug in the treatment of
tuberculosis, is an analogue of and shares the same biochemical
mechanism with nicotinamide.
Benefits of
Niacinamide
Nicotinamide, unlike nicotinic acid,
does not have significant effects on lipids, but it has been shown
to be useful for some with type 1 (insulin-dependent) diabetes.
There is preliminary evidence showing that it might help some with
generalized granuloma annular and osteoarthritis. There is little
evidence that it is helpful in rheumatoid arthritis or
schizophrenia. There is a suggestion that it might aid in some
cancer therapies. There is little evidence that it is useful in
tinnitus.
Nicotinamide is being investigated as an agent for
the possible prevention or delaying of the onset of type 1 diabetes
mellitus (insulin-dependent diabetes mellitus or IDDM). The
rationale for using nicotinamide to prevent type 1 diabetes mellitus
is derived from human and animal studies as well as in vitro
investigations. Nicotinamide has been found to prevent diabetes in
alloxan- and streptozotocin-treated mice and rats and in non-obese
diabetic (NOD) mice. In vitro studies have shown that nicotinamide
can prevent macrophage- or interleukin-1beta-induced beta-cell
damage. An intervention study in New Zealand using nicotinamide
treatment showed a 50% reduction in the development of IDDM over a
five-year period.
Nicotinamide has been shown to have
antioxidant activity. In vitro, it has been found to inhibit protein
oxidation and lipid peroxidation. It has also been found to inhibit
reactive oxygen species-induced apoptosis, to inhibit phagocytic
generation of reactive oxygen species, to scavenge reactive oxygen
species and to inhibit the oxidative activity of nitric
oxide.
Nicotinamide has demonstrated a number of
anti-inflammatory activities. Nicotinamide has been shown to inhibit
lipopolysaccharide-induced TNF-alpha in the mouse, in a
dose-dependent manner. It is thought that this inhibition of
TNF-alpha is mediated via inhibition, at the gene transcription
level, of NF-Kappa B, which in turn inhibits TNF-alpha. Nicotinamide
has also been shown to decrease the production of IL-12 and
TNF-alpha in cultures of whole blood from prediabetic and diabetic
subjects and also in healthy subjects.
Dosage and
Administration
Nicotinamide is the form of niacin
which is typically used for nutritional supplementation. It is also
the form of niacin used in food fortification. It is available as a
single ingredient product (immediate-release and sustained-release)
and in multivitamin and multivitamin/multimineral products. Typical
supplemental dosage ranges from 20 to 100 milligrams daily. Pre- and
postnatal vitamin/mineral supplements typically deliver a dose of 20
milligrams daily.
|
