Frezep

Uses

Vitamin C is used for prevention and treatment of scurvy. It may be used for 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.

Selenium is an ingredient found in a variety of supplements and vitamins.

For the supplementation of total parenteral nutrition to prevent hyposelenemia .

Frezep is also used to associated treatment for these conditions: Common Cold, Deficiency, Vitamin A, Deficiency, Vitamin D, Fever, Flu caused by Influenza, Folate deficiency, Iron Deficiency (ID), Iron Deficiency Anemia (IDA), Oral bacterial infection, Scurvy, Vitamin C Deficiency, Vitamin Deficiency, Nutritional supplementation, Vitamin supplementationNutritional supplementation

How Frezep works

In humans, an exogenous source of ascorbic acid is required for collagen formation and tissue repair by acting as a cofactor in the posttranslational formation of 4-hydroxyproline in -Xaa-Pro-Gly- sequences in collagens and other proteins. Ascorbic acid is reversibly oxidized to dehydroascorbic acid in the body. These two forms of the vitamin are believed to be important in oxidation-reduction reactions. The vitamin is involved in tyrosine metabolism, conversion of folic acid to folinic acid, carbohydrate metabolism, synthesis of lipids and proteins, iron metabolism, resistance to infections, and cellular respiration.

Selenium is first metabolized to selenophosphate and selenocysteine. Selenium incorporation is genetically encoded through the RNA sequence UGA . This sequence is recognized by RNA ste loop structures called selenocysteine inserting sequences (SECIS). These structures require the binding of SECIS binding proteins (SBP-2) to recognize selenocystiene. The specialized tRNA is first bound to a serine residue which is then enzymatically processed to a selylcysteyl-tRNA by selenocystiene sythase using selenophosphate as a selenium donor. Other unidentified proteins are required as part of the binding of this tRNA to the ribosome. Selenoproteins appear to be necessary for life as mice with the specialized tRNA gene knocked out exhibited early embryonic lethality .

The most important selenoproteins seem to be the glutathione peroxidases and thioredoxin reductases which are part of the body's defenses againts reactive oxygen species (ROS) . The importance of selenium in these anti-oxidant proteins has been implicated in the reduction of atherosclerosis by preventing the oxidation of low density lipoprotein . Selenium supplementation is also being investigated in the prevention of cancer and has been suggested to be beneficial to immune function .

Dosage

Frezep dosage

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.

Side Effects

Ascorbic acid does not seem to have any important adverse effects at dosages less than 4 mg/day. Larger dose may cause diarrhoea or formation of renal calculi of calcium oxalate in patients with renal impairment. Ingestion of more than 600 mg daily have a diuretic action.

Toxicity

Oral LD50 of 6700mg/kg in rats . Selenium exposure is teratogenic and can result in fetal death as tested in mice. Chronic toxicity is characterized by hair loss, white horizontal streaking on fingernails, paronchyia, fatigue, irritability, hyperreflexia, nausea, vomiting, garlic odor on breath, and metallic taste . Serum selenium correlates weakly with symtoms. Blood chemistry as well as liver and kidney function are normally unnaffected. Acute toxicity presents as stupor, respiratory depression, and hypotension. ST elevations and t-wave changes characteristic of myocardial infarction may be observed.

Precaution

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.

Interaction

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.

Elimination Route

70% to 90%

Oral bioavailability of 90% when given as L-selenomethionine . Tmax of 9.17h.

Half Life

16 days (3.4 hours in people who have excess levels of vitamin C)

Half life was observed to increase with chronic dosing time . For day 1-2 half life was 1.7 days. For day 2-3 half life was 3 days. For day 3-14 half life was 11.1 days.

Elimination Route

Mainly excreted in urine as 1beta-methylseleno-N-acetyl-d-galactosamine and trimethylselenonium . The amount excreted as 1beta-methylseleno-N-acetyl-d-galactosamine plateaus at doses around 2microg after which the amount excreted as trimethylselenonium increases. Some selenium is also excreted in feces when given orally .

Pregnancy & Breastfeeding use

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.

Storage Condition

Should be stored in a dry place below 30˚C.

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