A 35 year old alcoholic presents with diarrhoea and scaly rash on his neck, hands and feet. He will improve if he is treated with which one of the following ?

*Niacin encompasses nicotinic acid and nicotinamide . *Niacin deficiency causes pellagra - diarrhea,dermatitis, dementia,death Niacin encompasses nicotinic acid and nicotinamide. Nicotinamide is an essential pa of the two pyridine nucleotides, nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), which play a key role as hydrogen acceptors and donors for many enzymes. Niacin can be synthesised in the body in limited amounts from the amino acid tryptophan. Deficiency - pellagra Pellagra was formerly endemic among poor people who subsisted chiefly on maize, which contains niacytin, a form of niacin that the body is unable to utilise. Pellagra can develop in only 8 weeks in individuals eating diets that are very deficient in niacin and tryptophan. It remains a problem in pas of Africa, and is occasionally seen in alcoholics and in patients with chronic small intestinal disease in developed countries. Pellagra can occur in Hanup's disease, a genetic disorder characterised by impaired absorption of several amino acids, including tryptophan. It is also seen occasionally in carcinoid syndrome (p. 678), when tryptophan is consumed in the excessive production of 5-hydroxytryptamine (5-HT, serotonin). Pellagra has been called the disease of the three Ds: * Dermatitis. Characteristically, there is erythema resembling severe sunburn, appearing symmetrically over the pas of the body exposed to sunlight, paicularly the limbs and especially on the neck but not the face (Casal's necklace, Fig. 19.13). The skin lesions may progress to vesiculation, cracking, exudation and secondary infection. * Diarrhoea. This is often associated with anorexia, nausea, glossitis and dysphagia, reflecting the presence of a non-infective inflammation that extends throughout the gastrointestinal tract. * Dementia. In severe deficiency, delirium occurs acutely and dementia develops in chronic cases. Treatment is with nicotinamide, given in a dose of 100 mg 3 times daily orally or parenterally. The response is usually rapid. Within 24 hours the erythema diminishes, the diarrhoea ceases and a striking improvement occurs in the patient's mental state. Ref Harrison 20th edition pg 98e