DESCRIPTION:
Retinol and derivatives of retinol that play an essential role in metabolic functioning of the retina, the growth of and differentiation of epithelial tissue, the growth of bone, reproduction, and the immune response. Dietary vitamin A is derived from a variety of carotenoids found in plants. It is enriched in the liver, egg yolks, and the fat component of dairy products.
COMPOSITION:
Each soft gelatin capsules contains:
Vitamin A USP 2,00,000 I.U.
(As palmitate)
Excipients Q.S.
Approved colours used in capsule shell.
PHARMACOLOGY:
Mechanism of Action
Vitamin A (all-trans retinol) is converted in the retina to the 11-cis-isomer of retinaldehyde or 11-cis-retinal. 11-cis-retinal functions in the retina in the transduction of light into the neural signals necessary for vision. 11-cis-retinal, while attached to opsin in rhodopsin is isomerized to all-trans-retinal by light. This is the event that triggers the nerve impulse to the brain which allows for the perception of light. All-trans-retinal is then released from opsin and reduced to all-trans-retinol. All-trans-retinol is isomerized to 11-cis-retinol in the dark, and then oxidized to 11-cis-retinal. 11-cis-retinal recombines with opsin to re-form rhodopsin. Night blindness or defective vision at low illumination results from a failure to re-synthesize 11-cis retinal rapidly.
Epithelial differentiation: The role of Vitamin A in epithelial differentiation, as well as in other physiological processes, involves the binding of Vitamin A to two families of nuclear retinoid receptors (retinoic acid receptors, RARs; and retinoid-X receptors, RXRs). These receptors function as ligand-activated transcription factors that modulate gene transcription. When there is not enough Vitamin A to bind these receptors, natural cell differentiation and growth are interrupted.
PHARMACOKINETICS
Absorption
Readily absorbed from the normal gastrointestinal tract.
Metabolism
Hepatic. Retinol is conjugated with glucuronic acid; the B-glucuronide undergoes enterohepatic circulation and oxidation to retinol and retinoic acid. Retinoic acid undergoes decarboxylation and conjugation with glucuronic acid.
Protein binding
<5% of circulating vitamin A is bound to lipoproteins in blood in normal condition, but may be up to 65% when hepatic stores are saturated because of excessive intake. When released from liver, vitamin A is bound to retinol-binding protein (RBP). Most vitamin A circulates in the form of retinol bound to RBP.
INDICATIONS:
Effective for
Possibly Effective for
CONTRAINDICATIONS:
Avoid use if hypersensitivity, intravenous use, hypervitaminosis A, malabsorption syndrome (oral therapy) and pregnancy.
DOSAGE AND ADMINISTRATION:
Recommended daily intakes:
Men – 900 mcg/day (3,000 IU)
Women – 700 mcg/day (2,333IU)
ADULTS BY MOUTH:
General: Recommended Dietary Allowance (RDA) levels for adults have been established: men 14 years and older, 900 mcg/day (3000 IU); women 14 years and older, 700 mcg/day (2300 IU); pregnancy 14 to 18 years, 750 mcg/day (2500 IU); 19 years and older, 770 mcg/day (2600 IU); lactation 14 to 18 years, 1200 mcg/day (4000 IU); 19 years and older, 1300 mcg/day (4300 IU). Tolerable Upper Intake Levels (UL) for vitamin A have also been established. The UL is the highest level of intake that is likely to pose no risk of harmful effects. The ULs for vitamin A are for preformed vitamin A (retinol) and do not include provitamin A carotenoids: adolescents 14 to 18 years (including pregnancy and lactation), 2800 mcg/day (9000 IU); adults age 19 and older (including pregnancy and lactation), 3000 mcg/day (10,000 IU).
CHILDREN BY MOUTH:
General: Adequate Intake (AI) levels of vitamin A for infants have been established: birth to 6 months, 400 mcg/day (1300 IU); 7 to 12 months, 500 mcg/day (1700 IU).
ADMINISTRATION
Oral Administration
Administer vitamin A orally with or after meals.
WARNING &PRECAUTIONS:
Warnings
Avoid use if hypersensitivity, intravenous use, hypervitaminosis A, malabsorption syndrome (oral therapy), and pregnancy (recommended daily average).
This medication contains vitamin A. Do not take Retinol, Aquasol A, Retinyl Acetate, or Retinyl Palmitate if you are allergic to vitamin A or any ingredients contained in this drug.
Keep out of reach of children. In case of overdose, get medical help or contact a Poison Control Center immediately.
PREGNANCY& LACTATION:
DRUG INTERACTION:
Calcium Carbonate; Risedronate: (Minor) Doses in excess of 1,500 to 2,000 mcg per day of Vitamin A may lead to bone loss and will counteract the effects of risedronate therapy.
Calcium: (Minor) Doses in excess of 1,500 to 2,000 mcg per day of Vitamin A may lead to bone loss and will counteract the effects of supplementation with calcium salts.
Castor Oil: (Moderate) Absorption of fat-soluble vitamins may be decreased with coadministration of castor oil.
Cholestyramine: (Moderate) Cholestyramine can decrease the intestinal absorption of fat and fat-soluble vitamins. If used concurrently, administration of the two agents should be staggered for the longest time interval possible.
Cod Liver Oil: (Severe) Patients should avoid or limit supplementation with vitamin A during treatment with retinoids to avoid potential additive toxic effects.
Colesevelam: (Moderate) It is not known if colesevelam can reduce the absorption of oral vitamin supplements including fat soluble vitamins A, D, E, and K. To minimize potential interactions, administer vitamins at least 4 hours before colesevelam.
Colestipol: (Moderate) Separate administration of fat-soluble vitamins by 1 hour before or 4 hours after a colestipol dose to limit effects on oral absorption. Because it sequesters bile acids, colestipol may interfere with normal fat absorption and thus may reduce absorption of fat-soluble vitamins.
Methoxsalen: (Moderate) Use methoxsalen and retinoids together with caution; the risk of severe burns/phototoxicity may be additive. If concurrent use is necessary, closely monitor patients for signs or symptoms of skin toxicity.
SIDE EFFECT:
Common Side Effects of Vitamin A
Side effects from taking moderate doses of vitamin A do not occur often.
Serious Side Effects of Vitamin A
These are especially likely to occur under high doses of vitamin A:
STORAGE:Store at room temperature.
PRESENTATION:Blister Pack of 10×10 (100 capsules) in a Box