ASCOBEX

VITAMIN C [ASCORBIC ACID]

Vitamin C is indicated for prevention and treatment of scurvy. It may be indicated in pregnancy, lactation, infection, trauma, burns, cold exposure, following surgery, fever, stress, peptic ulcer, cancer, methaemoglobinaemia and in infants receiving unfortified formulas. It is also prescribed for haematuria, dental caries, pyorrhea, acne, infertility, atherosclerosis, fractures, leg ulcers, hay fever, vascular thrombosis prevention, levodopa toxicity, succinyl-choline toxicity, arsenic toxicity etc. To reduce the risk of stroke in the elderly, long-term supplementation with Vitamin C is essential.

Vitamin-C Preparations

Pyrodoxine (Vitamin B6) is a water-soluble vitamin which functions in the metabolism of carbohydrates, proteins and fats. It is essential in Hb formation and GABA synthesis within the CNS. It also aids in the release of glycogen stored in the liver and muscles. Folic acid (Vitamin B9) is essential for the production of certain coenzymes in many metabolic systems such as purine and pyrimidine synthesis. It is also essential in the synthesis and maintenance of nucleoprotein in erythropoesis. It also promotes WBC and platelet production in folate-deficiency anaemia. Cyanocobalamin (Vitamin B12) is vital to growth, hematopoiesis and nucleoprotein and myelin synthesis. As a hematopoietic agent, it is converted to coenzyme B12 needed in the conversion of methylmalonate to succinate and production of methionine from homocysteine, a reaction requiring folate. In the absence of folate, such metabolites cannot be formed and folate deficiency occurs. It is also involved in the maintenance of reduced sulfhydryl (SH) groups which are required by various SH-activated enzyme systems. Through such processes, cyanocobalamin participates in fat and carbohydrate metabolism as well as protein synthesis.

Oral administration- For the prevention of scurvy: 1 tablet daily For the treatment of scurvy: 1-2 tablets daily; but dose may be increased depending on the severity of the condition. For the reduction of risk of stroke in the elderly: 1-2 tablets daily. In other cases: 1 tablet daily or as directed by the physician. Maximum safe dose is 2000 mg daily in divided doses. Parenteral administration- Vitamin C is usually administered orally. When oral administration is not feasible or when malabsorption is suspected, the drug may be administered IM, IV, or subcutaneously. When given parenterally, utilization of the vitamin reportedly is best after IM administration and that is the preferred parenteral route. For intravenous injection, dilution into a large volume parenteral such as Normal Saline, Water for Injection, or Glucose is recommended to minimize the adverse reactions associated with intravenous injection. The average protective dose of vitamin C for adults is 70 to 150 mg daily. In the presence of scurvy, doses of 300 mg to 1 g daily are recommended. However, as much as 6 g has been administered parenterally to normal adults without evidence of toxicity. To enhance wound healing, doses of 300 to 500 mg daily for a week or ten days both preoperatively and postoperatively are generally considered adequate, although considerably larger amounts have been recommended. In the treatment of burns, doses are governed by the extent of tissue injury. For severe burns, daily doses of 1 to 2 g are recommended. In other conditions in which the need for vitamin C is increased, three to five times the daily optimum allowances appear to be adequate. Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever the solution and container permit.

Potentially hazardous interactions: Ascorbic acid is incompatible in solution with aminophylline, bleomycin, erythromycin, lactobionate, nafcillin, nitrofurantoin sodium, conjugated oestrogen, sodium bicarbonate, sulphafurazole diethanolamine, chloramphenicol sodium succinate, chlorthiazide sodium and hydrocortisone sodium succinate. Useful interactions: Ascorbic acid increases the apparent half-life of paracetamol and enhances iron absorption from the gastrointestinal tract.

Vitamin C has little toxicity and only mega-doses of vitamin C may cause diarrhoea, abdominal bloating, iron over-absorption that is harmful in patients with thalassaemia, sideroblastic anemia, and haemochromatosis; hyperoxaluria, hyperuricosuria, and hemolysis in patients with glucose-6 phosphate dehydrogenase deficiency. A pregnant woman taking more than 5 gm/day may suffer fetal abortion.

The drug is safe in normal doses in pregnant women, but a daily intake of 5 gm or more is reported to have caused abortion. The drug may be taken safely during lactation.

Ingestion of megadose (more than 1000 mg daily) of vitamin C during pregnancy has resulted in scurvy in neonates. Vitamin C in mega-doses has been contraindicated for patients with hyperoxaluria. Vitamin C itself is a reactive substance in the redox system and can give rise to false positive reactions in certain analytical tests for glucose, uric acid, creatine and occult blood.

Should be stored in a dry place below 308C.