⭕️Vitamin A is a general term encompassing various fat-soluble substances such as retinol, retinyl palmitate, and beta-carotene.

⭕️Dose &dosage form:

7500,8000,25000iu capsule 

50000u/ml injectable

⭕️Indication 

Vitamin A supplementation is offered for the treatment of measles, xerophthalmia, severe malnutrition and to prevent deficiency in pregnant women living in areas endemic to vitamin A deficiency.

Vitamin A’s involvement in cell morphogenesis, differentiation, and proliferation is essential to gene regulation. Additionally, its function as an antioxidant decreases free radical damage to DNA.

⭕️Mechanism of Action

In the liver, retinol is esterified to retinyl esters and stored in the stellate cells. Both retinol and beta-carotene are oxidized to retinal and retinoic acid in the tissues, which are essential for vision and gene regulation, respectively. These active metabolites bind nuclear receptors of the RAR family to control gene expression

⭕️Adverse effect

Acute vitamin A toxicity may occur with a single ingestion of 25,000 IU/kg or more. Signs and symptoms include nausea, vomiting, diarrhea, dizziness, lethargy, drowsiness, increased intracranial pressure, and skin changes such as erythema, pruritus, or desquamation.

Chronic vitamin A toxicity may occur with excessive ingestion of 4000 IU/kg or more daily for 6 to 15 months. Signs and symptoms include low-grade fever, headache, fatigue, anorexia, intestinal disturbances, hepatosplenomegaly, anemia, hypercalcemia, subcutaneous swelling, nocturia, joint and bone pain, and skin changes like yellowing, dryness, alopecia, and photosensitivity. 

⭕️References

Moise AR, Noy N, Palczewski K, Blaner WS. Delivery of retinoid-based therapies to target tissues. Biochemistry. 2007 Apr 17;46(15):4449-58