Study on the incorporation of 59Fe-sodium ferrous citrate into the blood, milk, and each tissue of maternal and neonatal rats after dosing to lactating rats

The incorporation of 59 Fe-sodium ferrous citrate (SCF) into blood, milk, and each tissue is compared with 59 Fe-ferrous sulfate (FeSO 4 )in both maternal rats and their neonates after a single oral administration to the lactating rats at a dose of 1.5 mg Fe/5 ml/kg (7.5 μCi/kg). A high concentration of radioactivity in the SCF-treated rats was observed in maternal blood, liver, spleen, and bone 24 h after each compound oral administration. However, 96 h after dosing, the difference on the concentration of 59 Fe between SCF and FeSO 4 in each tissue except blood fell to almost the same level. The incorporation of 59 Fe into the red blood cells in lactating rats showed maximum level at 72 h in 59 Fe-SCF and 96 h in 59 FeSO 4 after oral administration. At each peak level in red blood cells 59 Fe concentration in 59 Fe-SCF-treated rats was estimated to be 3-fold compared with that of 59 FeSO 4 . On the other hand, at 24 h after oral administration of 59 Fe-SCF to lactating rats the radioactivity of neonatal rats indicated almost the same in liver and spleen and lower level in bone and blood than maternal rats. In addition, 59 Fe-SCF showed a rapid incorporation rate of 59 Fe in neonatal rats higher than 59 FeSO 4 when both compounds were administered to the maternal rats. But at 96 h after dosing a lower concentration of 59 Fe in neonatal rats whose mothers were treated with SCF was noted in liver, spleen, and blood as compared with neonatal rats whose mothers had been treated with FeSO 4 , but heart and bone Fe concentration in SCF was higher than FeSO 4 . The maximum Fe levels in milk at 3 h by 59 Fe-SCF-treated were observed 1.3-fold higher compared to that at 6 h by 59 FeSO 4 -treated and Fe levels in milk by 59 Fe-SCF continued to 12 h, but that of 59 FeSO 4 disappeared moderately with time. In addition, the ratios of milk-to-plasma concentration showed 8.1 ( 59 Fe-SCF: 12 h) and 3.3 ( 59 FeSO 4 : 6 h) after both oral administration to lactating rats, respectively. The present study suggests that Fe-SCF has a good bioavailability to lactating and also benefit for premature rats via milk of maternal rats more than those of FeSO 4 .