Adults

For vitamin C deficiency: 250-500 mg daily. For general supplementation: 250 mg daily or as directed by a physician.

Elderly

Same as adult dosage, usually 250 mg daily for supplementation.

Renal_impairment

Use with caution in severe renal impairment due to the risk of oxalate stone formation with high doses. Consult a physician for appropriate dosing.

Onset

Relatively rapid absorption with peak plasma levels typically within 2-3 hours.

Excretion

Excreted primarily by the kidneys. Excess amounts are rapidly excreted unchanged in the urine. Renal threshold for excretion is about 1.5 mg/dL.

Half life

Plasma half-life varies, generally 8-40 minutes for small doses, but can be several hours with saturated body stores.

Absorption

Readily absorbed from the gastrointestinal tract, primarily in the small intestine. Absorption decreases with increasing dose.

Metabolism

Partially metabolized in the liver to inactive metabolites, including ascorbic acid-2-sulfate and oxalic acid.

Aspirin

Aspirin may decrease Vitamin C absorption and increase its urinary excretion.

Warfarin

High doses of Vitamin C may potentially decrease the anticoagulant effect of warfarin.

Iron supplements

Vitamin C enhances the absorption of non-heme iron.