Adult: As treatment: Not less than 250 mg daily in divided doses. Max: 1000 mg daily. As prophylaxis: 25-75 mg daily. Doses are individualised according to patient’s needs. Dosage recommendation may vary among countries or individual products. Refer to specific product guidelines. Child: Dosage recommendation may vary among countries or individual products. Refer to specific product guidelines.
Parenteral Scurvy
Adult: 300-1000 mg daily, given via IM, IV or SC inj. Doses are individualised according to patient's needs. Dosage recommendation may vary among countries or individual products. Refer to specific product guidelines. Child: Initially, 100-300 mg daily in divided doses for 1 week then 100 mg daily until stabilisation of tissue saturation. Dosage recommendation may vary among countries or individual products. Refer to specific product guidelines.
Administration
May be taken with or without food.
Reconstitution
IV: Add a daily dose to an appropriate volume of suitable solution (e.g. 5% dextrose in water, sterile water for inj). Add the solutes as necessary to make the final solution isotonic. Instructions for reconstitution may vary among countries or individual products. Refer to specific product guidelines.
Incompatibility
Parenteral: Incompatible with ferric salts, oxidising agents, salts of heavy metals (e.g. Cu), aminophylline, bleomycin sulfate, erythromycin lactobionate, nafcillin Na, nitrofurantoin Na, conjugated estrogens, Na bicarbonate, sulfafurazole diethanolamine. Occasionally, chloramphenicol Na succinate (depending on pH or concentration).
Special Precautions
Patient with diabetes mellitus, G6PD deficiency, haemochromatosis, history of renal stones (e.g. oxalate kidney stones), predisposition to recurrent renal calculi. Renal impairment. Children (<2 years of age) and elderly. Pregnancy and lactation.
Adverse Reactions
Significant: Acute or chronic oxalate nephropathy (prolonged use; large doses). Gastrointestinal disorders: Diarrhoea, nausea, vomiting, heartburn. General disorders and administration site conditions: Fatigue, pain at the inj site. Nervous system disorders: Dizziness, headache. Vascular disorders: Flushing.
Monitor renal function (patient with a predisposition to oxalate nephropathy), haemoglobin, and blood counts (G6PD deficient patient).
Overdosage
Symptoms: Diarrhoea, formation of renal oxalate calculi. Management: Supportive and symptomatic treatment.
Drug Interactions
Increased absorption of Fe. Increased excretion of Fe with desferrioxamine. Induced tissue desaturation with aspirin, nicotine, Fe, phenytoin, tetracycline, estrogen in oral contraceptives, some appetite suppressants and anticonvulsants. May increase the absorption of Al-containing antacids. May diminish the activity of anticoagulants (e.g. warfarin). May increase the serum concentration of estrogen derivatives. May decrease the serum concentration of amphetamines.
Food Interaction
Alcohol may decrease ascorbic acid levels.
Lab Interference
May interfere test results based on oxidation-reduction reactions (e.g. leucocyte count, blood and urine glucose testing, nitrite and bilirubin levels). May cause false-negative faecal occult blood test.
Action
Description: Mechanism of Action: Ascorbic acid, a water-soluble vitamin that acts as a cofactor and as an antioxidant. It is essential for connective tissue synthesis, and Fe absorption and storage. Additionally, it is an electron donor used for collagen hydroxylation, carnitine biosynthesis, and hormone or amino acid synthesis.
Synonym: vitamin C. Onset: 2 days to 3 weeks (reversal of scurvy symptoms). Pharmacokinetics: Absorption: Well absorbed from the gastrointestinal tract. Bioavailability: Approx 100% (Oral: for doses up to 200 mg). Distribution: Crosses the placenta, enters breast milk. Widely distributed in the body tissues; distributed to the pituitary and adrenal glands, eye tissues and humours, leucocytes, and brain; low concentration in the plasma and saliva. Metabolism: Reversibly metabolised via oxidation into dehydroascorbic acid (active), partly metabolised to inactive compounds including ascorbic-acid-2-sulfate and oxalic acid. Excretion: Via urine (with high concentrations); minimal excretion in subthreshold levels (up to 80 mg/day). Elimination half-life: 10 hours.
Chemical Structure
Ascorbic acid Source: National Center for Biotechnology Information. PubChem Database. Ascorbic acid, CID=54670067, https://pubchem.ncbi.nlm.nih.gov/compound/Ascorbic-acid (accessed on Jan. 21, 2020)
Storage
Oral: Store below 25°C. Protect from light and moisture. Parenteral: Store between 2-8°C. Protect from light.
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