Vitamin B6 & Deficiency

Pyridoxine reduces the effect of Levodopa in the treatment of parkinsonism.

It is co-decarboxylase and by facilitating decarboxylation of levodopa reduces its blood level.

It interacts with isoniazid and reduces the toxicity of isoniazid in slow acetylators.

The hypotensive effect of hydralazine is reduced if pyridoxine is added along with it.

Ref: John Parry Griffin, P. F. D’Arcy, Patrick Francis D’Arcy (1997), Elsevier Publications, In the book, “A Manual of Adverse Drug Interactions”, 5th Edition, Page 367 ; KD Tripathy, 5th Edition, Pages 823 – 824

Pyridoxine (Vitamin B6):

• Vitamin B6 refers to a family of compounds that include pyridoxine, pyridoxal, pyridoxamine, and their 5′-phosphate derivatives. 
• 5′-Pyridoxal phosphate (PLP) is a cofactor for enzymes that involved in amino acid metabolism. 
• Vitamin B6 also is involved in heme and neurotransmitter synthesis and in the metabolism of glycogen, lipids, steroids, sphingoid bases, and several vitamins, including the conversion of tryptophan to niacin.

• Peripheral neuropathy
• Abnormal electroencephalograms
• Personality changes that include depression and confusion.

Ans. is ‘a’ i.e., Isoniazid

o Alcoholism and isoniazid are contributing factors for pyridoxine deficiency.

o Clinical findings of pyridoxine deficiency are seborrhea, glossitis, convulsions, neuropathy, depression, confusion, microcytic anemia.

Contributing factors to deficiency of other vitamins. o Thiamine –> Alcoholism

o Niacin         —>      Alcoholism, Vit B₆ deficiency, Riboflavin deficiency.

o Folate        —>      Alcoholism, sulfasalazine, pyrimethamine, triamterene.

o VitB₁₂        —>       Gastric atrophy (pernicious anemia), terminal ileal disease, strict vegetarian

o VitC            —>      Smoking, alcoholism.

o Vit A           —>      Fat malabsorption, Protein energy malnutrition, Infection, measles, alcoholism.

o VitD            —>      Aging, lack of sunlight exposure, fat malabsorption.

o VitE             —>     Fat malabsorption, genetic abnormalities of vit E transport / metabolism.

o VitK            —>    Fat malabsorption, liver disease, antibiotic use.

Ans. is `b’ i.e., Homocystinuria

Inborn error of Metabolism and treatment

Ans. is ‘b’ i.e., Methyl-malonic acidemia

o For methyl malonic acidemia, Vit B₁, is given.

o I am not sure about option c & d.

Ans. is ‘c’ i.e., Xantheurenic acid

Ans. is ‘d’ i.e., Homocystinuria