A 29 year old medical student developed a positive PPD (purified protein derivative) test. She was staed on isoniazid (INH) and rifampin prophylaxis. Three months into her therapy, she began to experience muscle fasciculations and convulsions. Administration of which of the following vitamins might have prevented these symptoms?

Pyridoxine, or vitamin B6, is sometimes depleted with isoniazid (INH) use. Patients with pyridoxine deficiency may experience neurologic symptoms, such as convulsions and fasciculations. The treatment of this disorder is slow IV administration of 2-5 g of pyridoxine. Niacin deficiency, also known as pellagra, is a disease that involves several organs, including the skin, the gastrointestinal system, and the nervous system. A useful mnemonic for remembering the symptoms of pellagra is the "4 D's": dermatitis, dementia, diarrhea, and death. These symptoms are not consistent with the patient history described in the question. Riboflavin deficiency is not typically seen alone, but rather in conjunction with other vitamin deficiencies. Dermatitis and glossitis are the most frequent clinical manifestations. Thiamine deficiency, or beri-beri, presents with dry skin and paralysis, rather than convulsions. Severe thiamine deficiency produces Wernicke's encephalopathy, with disorientation, ataxia, and ophthalmoplegia. This deficiency is typically seen in alcoholic patients. Ref: Amato A.A., Barohn R.J. (2012). Chapter 384. Peripheral Neuropathy. In D.L. Longo, A.S. Fauci, D.L. Kasper, S.L. Hauser, J.L. Jameson, J. Loscalzo (Eds),Harrison's Principles of Internal Medicine, 18e.