Developmental changes in serum half-life of (EZ)-cyclobilirubin.
BACKGROUND
Phototherapy has been a standard treatment for neonatal hyperbilirubinemia for more than 40 years, but it has remained sub-optimal.


OBJECTIVE
To clarify the developmental changes in parameters of (4E, 15Z)-cyclobilirubin ((EZ)-C) elimination in order to obtain basic data for establishing optimal phototherapy.


METHODS
Blood samples were taken at regular intervals after stopping phototherapy, and bilirubin fractions were analyzed by high-performance liquid chromatography.


METHODS
The subjects were 46 infants with hyperbilirubinemia who underwent phototherapy. The gestational age and birth weight of the subjects ranged from 25.0 to 41.0 weeks and from 656 to 3810 g, respectively, and the age at cessation of phototherapy was a median of 5 days. A kinetic model of (EZ)-C elimination was established, and the serum half-life of (EZ)-C was calculated on the basis of the determined model. Relationships of the half-life of (EZ)-C with birth weight and gestational age were investigated.


RESULTS
Serum (EZ)-C elimination followed a first-order kinetic model in 43 infants and a zero-order kinetic model in three extremely low birth weight infants. The half-life of (EZ)-C calculated on the basis of a first-order elimination model in serum ranged from 68 to 274 min and showed weak negative correlations with birth weight and gestational age.


CONCLUSIONS
Serum (EZ)-C excretion followed a first-order kinetic model in most of the neonates. The half-life of (EZ)-C becomes more prolonged in the very low birth weight infant and early gestational age.
Okada
Hitoshi
H
Department of Pediatrics, Kagawa University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa, 761-0793, Japan. hiokada@kms.ac.jp
Masuya
Kumiko
K
Yasuda
Saneyuki
S
Okubo
Kensuke
K
Kawada
Kou
K
Kusaka
Takashi
T
Namba
Masanori
M
Nishida
Tomoko
T
Imai
Tadashi
T
Isobe
Kenichi
K
Itoh
Susumu
S
D001663:Bilirubin / Q000031:analogs & derivatives* / Q000097:blood; D001724:Birth Weight; D006207:Half-Life; D006801:Humans; D051556:Hyperbilirubinemia, Neonatal / Q000097:blood / Q000628:therapy*; D007231:Infant, Newborn; D007700:Kinetics; D010789:Phototherapy
C041079:cyclobilirubin; D001663:Bilirubin