Effect of Nicotinic Acid as add-on Therapy in Patients Receiving β Blocker for Prophylaxis of Moderate to Severe Migraine: A Randomized, Double-blind, Placebo-controlled Trial

Migraine is "a common episodic neurological disorder with complex pathophysiology that manifests as recurrent attacks of typically throbbing and unilateral, often severe headache with certain associated features such as nausea, phonophobia, and photophobia". Worldwide, estimated prevalence was 13.8% to 15%. Quality of life of a migraine patient is extremely low and migraine badly hampers one's physical, emotional, and social efficiency and disrupt familial, social and professional relationships. Diagnosis is solely clinical depending on characteristics of headache and associated symptoms. Neuroimaging can be done only when exclusion of another cause of headache is needed.

Exact etiology and pathophysiology of migraine is unknown and multifactorial. There are several hypotheses of migraine pain generation. Local dilatation of intracranial and extracerebral vessels activate trigeminal nerve surrounding cerebral and meningeal vasculature. Migraine pain starts from the activation of trigeminovascular system. Afferent fibers innervating cerebral and meningeal vessels project to central nervous system and releases vasoactive peptides and inflammatory mediators. Some important mediators like Calcitonin gene related peptide (CGRP), NO, Substance P play role in inflammation and vasodilatation. Then sensitization and discharge of thalamic neuron and subsequent projection to sensory cortical neurons occurs. Thus, pain perception is received in migraine.

In studies, elevated levels of C reactive protein (CRP) and Transforming growth factor β (TGF-β) provides evidence of neuroinflammation. In migraine, impairment of cerebral mitochondrial energy metabolism and oxidative stress occurs. As a result, abnormalities in cerebral vasculature results in Cortical Spreading Depression (CSD).

Niacin, which is known as nicotinic acid or Vitamin B3 is the precursor of Nicotinamide Adenine Dinucleotide (NAD) or Nicotinamide Adenine Dinucleotide Phosphate (NADP). From dietary tryptophan, through kynurenine pathway, NAD is produced, and rest 1% tryptophan is catabolized to form serotonin (5- hydroxytryptamine/ 5-HT). Migraine is a serotonin deficient condition. It has been estimated that, dietary intake of Niacin is low in migraine patients.

Niacin supplementation provides enough NAD to inhibit Kynurenine pathway and accelerate production of 5-HT from tryptophan. Serotonin acting on 5-HT1 receptor, causes vasoconstriction. It may activate nerve endings in cerebral microcirculation and sensitize them to vasodilatory kinins. Serotonin also inhibits synthesis, release of NO, glutamate, Calcitonin gene-related peptide (CGRP). As a result, inhibition of afferent pain transmission and prevention of neuroinflammation occurs. Niacin also reduces inflammation evidenced by decrease level of pro inflammatory cytokines like IL-6, IL-1β, TNF α, high-sensitivity C-reactive protein (hs-CRP). Increasing level of Niacin also improves brain energy deficiency, and has potent antioxidant properties, which may be helpful in migraine prevention. However, more prospective investigations are necessary to validate niacin's preventive effect on migraine.