This study measured the time courses of concentration changes following administration of the catalytic
antioxidants Mn (III) tetrakis (4-benzoic acid) porphyrin (MnTBAP) and Mn (III) 3-methoxy N, N' bis (salicyclidene)
ethylenediamine chloride (EUK-134) in blood and cerebrospinal fluid (CSF) of rats with a spinal cord injury (SCI) and
sham controls. Parallel measurements were made for methylprednisolone, the only drug presently used clinically for
treating SCI. The time courses kinetically characterized the agents in their stability, disposition, and ability to penetrate
the blood–spinal cord barrier (BSB). In both the SCI and control groups, MnTBAP was stable in CSF and in blood across
the collection periods (10 h and 24 h, respectively) following administration. In the blood, [EUK-134] and
[methylprednisolone] rapidly declined to near basal concentrations at 4 h and 2 h, respectively, post-administration.
Therefore the order of stability in CSF and blood was MnTBAP >> EUK-134 > methylprednisolone. The maximum
CSF/blood concentration ratios for EUK-134, methylprednisolone and MnTBAP post-administration were: 32 ± 3.1%,
19.2 ± 6.4%, and 4.42 ± 0.73% in the injured rats, and 22 ± 6.5%, 17.8 ± 2.9%, and 1.0 ± 0.5% in the sham control
animals. This suggests an order of BSB penetration of EUK-134 > methylprednisolone >> MnTBAP. Despite much lower
penetration by MnTBAP compared with EUK-134 and methylprednisolone, a lower dose of MnTBAP because of its
stability provided a higher concentration in CSF than did the other agents given at higher doses. This finding supports
further exploration of MnTBAP as a potential treatment for SCI.