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  Vitamin A (Beta-carotene, Retinol, Dehydroretinol)

Pharmacokinetics | Indications | Routes of Administration and Dosage | Contra Indications | Precautions | Interactions | Brand Names


Systems General (systemic)
Category Fat soluble vitamin


Pharmacokinetics

Vitamin A occurs in several forms: Retinol, Dehydroretinol, Beta-carotene. It is absorbed in the intestine by hydrolysis and is absorbed by carrier transport and re-esterified. Compared to Retinol only about 30 % of Beta-carotene is absorbed.Retinol esters circulates in the chylomicrons and is stored in liver cells.Free retinol released by hepatocytes combines with retinol binding protein and is transported to target cells.



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Indications

Beta-carotene is converted in the body to vitamin A, which is necessary for good eye-sight and skin. Deficiency of vitamin A may cause night blindness . It also causes dry eyes[Xerosis],bitot spots, keratomalacia[softening of cornea], corneal opacities, eye infections, skin problems, and deficient growth. Some conditions may increase the need for beta-carotene or vitamin A. These include: Cystic fibrosis, diarrhoea, debilitating illness, injury, hepatic disease, malabsorption problems and pancreatic disease.



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Routes of Administration and Dosage

Prophylaxis for vitamin A difficiency: 3000-5000 IU/day. Treatment of established vitamin A deficiency: 50,000-100,000 IU/day I.M or oral for 1-3 days followed by intermittent supplement doses.



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Contra Indications

It may be contraindicated in severe hepatic disease.



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Precautions

Hypersensitivity reactions to the drug may occur. Precautions must be taken when taking the drug during pregnancy and breast-feeding. Excessive dosage leads to hypervitaminosis A.



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Interactions

Regular use of liquid paraffin can result in vitamin A deficiency. Long term oral neomycin induces steatorrhea and interferes with vitamin A absorption.



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Brand Names

Arovit drop[Roche]



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Pharmacokinetics | Indications | Routes of Administration and Dosage | Contra Indications | Precautions | Interactions | Brand Names

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