Preclinical pharmacokinetics, biodistribution, excretion, and plasma protein binding study of 58Fe-labeled hemin by ICP-MS.

BACKGROUND

Hemin, a stable form of heme iron, is a potential iron supplement for the treatment of iron deficiency. To date, the pharmacokinetics and in vivo ADME properties of hemin are to be elucidated.

METHODS

In this study, a rapid, sensitive, and validated inductively coupled plasma mass spectrometry (ICP-MS) method was used in combination with 58Fe stable isotope labeling to systemically investigate the plasma pharmacokinetics, biodistribution, excretion, and plasma binding profiles of hemin in animals.

RESULTS

Results showed that the ICP-MS method is accurate and sensitive enough to quantitatively determine the in vivo disposition process of 58Fe derived from 58Fe-labeled hemin. Following intra-gastric administration, 58Fe was rapidly absorbed in gastrointestinal tract, with Cmax of 41.1 ± 23.1 ng/mL, Tmax of 1.38 ± 0.48 h, and bioavailability of 1.12 ± 0.45 % in beagle dogs. Moreover, 58Fe was distributed to various organs including stomach, small intestine, spleen, and liver, within a few hours after intra-gastric administration in rats. Excretion of 58Fe in rats was predominantly via feces (76.3 ± 15.1 % of dosage), whereas minimally via urine (0.14 ± 0.08 % of dosage). Protein binding study revealed majority of 58Fe in plasma was bound to proteins, with average binding rates of 81.0 % and 92.7 % in human and rat plasma, respectively.

CONCLUSION

In conclusion, the present study validated the work-flow of preclinical pharmacokinetic studies of iron-containing drug candidates with using ICP-MS and stable (trace) isotope labeling strategy. It also provided useful information to support the further development of hemin as a drug/nutrition supplement candidate.