Weifa C-vitamin

The prevention and treatment of scurvy, or other conditions requiring vitamin C supplementation, where the deficiency is acute or oral administration is difficult.

Route of Administration: Parenteral

Adults

0.5 to 1g daily for scurvy, 200 to 500mg daily for preventative therapy.

Children

100 to 300mg daily for curative purposes, or 30mg daily for protective treatment.

Elderly

No special dosage requirements have been suggested.

Hyperoxaluria

Weifa C-vitamin should be given with care to patients with underlying renal failure due to the risk of formation of renal oxalate calculi. Tolerance may be induced in patients taking high doses.

Large doses of Weifa C-vitamin have resulted in haemolysis in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency.

Weifa C-vitamin injection is unlikely to affect the patient's ability to drive or use machinery.

Large doses may cause gastrointestinal disorders including diarrhoea. Large doses may also result in hyperoxaluria and renal oxalate calculi may form if the urine becomes acidic. Doses of 600mg or more daily have a diuretic action. Induced tolerance with prolonged use of large doses can result in symptoms of deficiency when intake is reduced to normal.

Large doses may cause gastrointestinal disorders including diarrhoea. Large doses may also result in hyperoxaluria and renal oxalate calculi may form if urine is acidic. Doses of 600mg or more daily have a diuretic action. Stop treatment and treat symptomatically.

ATC Code: A11G A01

Weifa C-vitamin, a water-soluble vitamin, is essential for formation of collagen and intercellular material, and therefore necessary for the development of cartilage, bone, teeth and for the healing of wounds. It is also essential for the conversion from folic acid to folinic acid, facilitates iron absorption from the gastro-intestinal tract and influences haemoglobin formation and erythrocyte maturation.

Distribution - widely distributed in body tissues with about 25% bound to plasma proteins. Large amounts are present in leucocytes and platelets. Weifa C-vitamin crosses the placenta.

Metabolism - readily oxidised to dehydroWeifa C-vitamin where some is metabolised to oxalic acid and the inactive ascorbate - 2 - sulphate. Metabolic turnover appears to be greater in females than males.

Excretion - large doses are rapidly excreted in the urine when in excess of the requirements of the body and after an intravenous dose, about 40% is excreted in 8 hours, which is increased to about 70% after tissue saturation. The amount of unchanged drug is dose dependent; in women the excretion of Weifa C-vitamin appears to vary with the stage of the menstrual cycle and it is decreased when taking oral contraceptives.

Weifa C-vitamin is excreted in breast milk.

Oxalic acid and ascorbate - 2 - sulphate are excreted in the urine.

None stated

Incompatible with ferric salts, oxidising agents, and salts of heavy metals, particularly copper.

Injections of Weifa C-vitamin have been reported to be incompatible with aminophylline, bleomycin sulphate, erythromycin lactobionate, nafcillin sodium, nitrofurantoin sodium, conjugated oestrogens, sodium bicarbonate and sulphafurazole diethanolamine. Occasional incompatibility, depending on pH or concentration, has occurred with chloramphenicol sodium succinate.

None stated