Study on circadian variation in folate pharmacokinetics

Background: In a new preparation of prenatal multivitamins, PregVit®, two tablets a day (a.m. and p.m.) are given. Folic acid is separated from iron and zinc and is given in the p.m. tablet to overcome problems due to folic acid interactions with iron or zinc, and frequent presence of nausea and vomiting of pregnancy in the morning. The circadian variation of folate in humans has not been investigated. This is the first study attempting to determine whether circadian variation of folate pharmacokinetics exists in humans. Objectives: To determine whether circadian rhythm of folate pharmacokinetics exists in humans. Methods: In a crossover design, six healthy, non-pregnant women were randomized to receive 1 tablet of PregVit® p.m., containing 1.1 mg of folic acid, in the morning or evening. Serum folate levels were measured over 10 hours. The area under the concentration-time curve (AUC) was used to compare the extent of absorption between the two time periods. Results: The mean AUC values for serum folate after administration of PregVit® p.m. were 334.5 ± 119.6 nM*h and 283.1 ± 64.3 nM*h for morning and evening, respectively (P = 0.17). The morning and evening peak serum folate concentrations were also similar (135.3 ± 41.7 nM and 130.3 ± 14.2 nM, respectively) (P = 0.75). Similarly, the time to peak for the morning arm (1 ± 0.5 hour) was similar to evening administration (1 ± 0.4 hour). Conclusions: There is no evidence of circadian variation in folate pharmacokinetics. Thus, the introduction of folate in PregVit® p.m. will not affect its effectiveness as compared to its routine administration in the morning.