Vitamins are non energy producing organic compounds essential for normal human metabolism, that must be supplied in small quantities in the diet. The importance of vitamins as drugs is primarily in the prevention and treatment of deficiency diseases, Vitamin deficiency occurs due to inadequate intake, malabsorption, increased tissue needs. increased excretion, certain genetic abnormalities and drug vitamin interactions. As Vit. A is stored in liver, deficiency symptoms appear only after long term deprivation.
