Folinic acid is available in the body for 6-8 hours. To extend the period during which it affects the body, it is customary to divide the daily dosage into 2 doses - one in the morning and the other in the afternoon. The second dose is preferred in the afternoon, rather than in the evening/night, to reduce sleep problems due to the stimulatory effect of the medication, as well as to achieve coverage of the medicine during the hours when the body is cognitively active.
The daily dose is typically limited to 50mg. Studies have shown that higher doses are poorly absorbed:
- At a dose of 25mg, absorption was 97%
- At a dose of 50mg, absorption was 75%
- At a dose of 100mg, absorption was 37%
According to the FDA medicine registration, it is recommended to limit a single dose of leucovorin to be up to 25mg. For example, with a daily dosage of 50mg, there is often a preference to divide the dosage into two separate doses of 25mg each.
Studies have shown that excess folinic acid is excreted in urine ("expensive pee" according to Dr. Frye).