Pharmacokinetics of Vitamin K(1) in Low-Birth-Weight Neonates

Abstract

The pharmacokinetics of vitamin K(1) was studied in 21 newborn infants. 11 neonates had received no parenteral loading dose prior to the study (group I), while 10 had been injected 5-10 mg vitamin K(1), at birth (group II). At postnatal age 2-9 h, 1 mg of vitamin K(1) was injected intravenously, and small samples of blood (≤ 500µl) were collected at different times during 6 h. Serum vitamin K(1) and its epoxide were assayed by high-performance liquid chromatography (HPLC). In both groups, the disappearance curve showed two exponential components: a fast distribution component during the 1 st h and a slower elimination component during the next 5 h. In group I, the plasma half-life of the first component was between 18 and 52 min (median 23 min), and the half-life of the second was between 67 and 179 min (median 109 min). Both half-lives were significantly higher in group II. The volumes of distribution were suggestive of distribution into plasma during the first phase and roughly into the extracellular water for the second component. Epoxide was detected in most patients 15 min after vitamin K(1) injection, and after 3 h its concentration was higher than the concentration of vitamin K(1). These data suggest that the kinetics of vitamin K(1) in neonates is not very different from that in adults. The newborn infant is able to oxidize vitamin K(1), a phenomenon in keeping with the gamma carboxylation of glutamic acid.

Vitamin K–containing dietary supplements: comparison of synthetic vitamin K1 and natto-derived menaquinone-7

“…Although the available data points do not allow accurate half-life time assessment, the decline of K1 was 86% in 4 hours, which is consistent with the reported short half-life time (1-2 h) for K 1 . 13,19,20 An estimate of the half-life time for MK-7 was obtained from the slope of the second phase of the decline (50% loss in 68 h), which is consistent with its reported very long half-life time (about 3 days). 13 In studies 2 to 4, we have investigated whether differences can also be found between the 2 K vitamins with respect to other characteristics, including circulating vitamin K concentrations at daily intake and efficacy of protein carboxylation.…”

Changes in Hepatic Vitamin K1 Levels After Prophylactic Administration to the Newborn

“…Moreover, the development of high performance liquid chromatography (HPLC) determination techniques has brought about a better understanding of the newborn's vitamin K status. Since then pharmacokinetic studies have been performed (5)(6)(7), vitamin KI concentrations across the placental barrier and at birth have been studied (8,9), and nutritional was also very rapid , since the median value after 48 h was 8.4 fLg/g and only 2.9 fLg/g 5 days after administration. However, hepatic total storage after 5 days in one infant with vitamin K1 supplementation was much higher (112 ug) than in infants who had not received supplementation.…”