The Toxicologist - Society of Toxicology

the observed CL values were 0.07 L/h in infants and ranged from 0.57 to 0.81 L/h
in adults. In summary, clearance of ENB-0040 in humans was well predicted using
this allometric modeling approach.
1584 CHARACTERIZATION OF THE TRANSPORT AND
INHIBITORY EFFECTS OF N-BUTYLPYRIDINIUM
CHLORIDE AND ITS STRUCTURALLY RELATED
IONIC LIQUIDS TO ROCT1/2.
Y. Cheng 1 , S. Wright 2 , R. Kuester 1 , M. Hooth 3 and I. Sipes 1 . 1 Pharmacology,
University of Arizona, Tucson, AZ, 2 Physiology, University of Arizona, Tucson, AZ
and 3 NIEHS, Research Triangle Park, NC.
Ionic liquids (ILs) are a class of salts often referred to “green chemicals”. They are expected
to be used as a new source of solvents and for many other applications. It has
been shown previously that N-butylpyridinium chloride (NBuPy-Cl) was rapidly
excreted in the rat kidney by glomerular filtration and renal secretion. This study investigated
the role of the rat organic cation transporter 1 or 2 (rOCT1/2) in urinary
secretion of ILs and their interaction with tetraethylammonium or metformin, substrates
of rOCT1/2. After CHO cells stably expressing rOCT1/2 were constructed,
transport of NBuPy-Cl, 1-methyl-3-butylimidazolium chloride (Bmim-Cl), and
N-Butyl-N-methylpyrrolidinium chloride (BmPy-Cl) was characterized. The ability
of NBuPy-Cl, Bmim-Cl, BmPy-Cl and alkyl substituted pyridinium to inhibit
rOCT1/2 was also determined in vitro. NBuPy-Cl was infused to rats to assess its
effect on the pharmacokinetics of metformin in vivo. NBuPy-Cl, Bmim-Cl and
BmPy-Cl were all substrates of rOCT1/2 with K t
values of 9/14 (rOCT1/2), 13/17
and 277/43 μM, respectively. They all exhibited strong inhibition to rOCT1/2
(IC 50
: 7.7~0.5 μM). The inhibitory effect of alkyl substituted pyridinium ILs increased
(IC 50
decreased) dramatically as the length of the side chain increases. The
IC 50
values were 762, 72, 5, 2 μM (H-,C 2
H 5
-, C 4
H 9
-, C 6
H 13
- pyridinium chloride)
for rOCT1 and 671, 14, 4, 0.1 μM for rOCT2. The in vivo co-administration
study revealed that NBuPy-Cl decreased the elimination rate of metformin and
therefore prolonged its plasma half-life in rats. These results show that ILs are transported
by rOCT1/2 and that they compete with other substrates of OCTs, which
can alter the in vivo pharmacokinetics of such substrates. This research was supported
by the NIEHS NTP Grant No. N01-ES-45529 and NIEHS-sponsored
Southwest Environmental Health Science Center Grant Number P30-ES-06694.
1585 COMPARATIVE PHARMACOKINETICS OF
PERFLUOROHEXANESULFONATE (PFHXS) IN RATS
AND MONKEYS.
S. Chang 1 , D. J. Ehresman 1 , P. E. Noker 2 , G. W. Olsen 1 , G. S. Gorman 2 , J. A.
Hart 1 , T. N. John 3 , M. Sundström 4 , Bergman 4 and J. L. Butenhoff 1 . 1 3M
Company, St. Paul, MN, 2 Sourthern Research Institute, Birmingham, AL, 3 Pace
Analytical Services, Minneapolis, MN and 4 Stockholm University, Stockholm,
Netherlands.
Perfluorohexanesulfonate (PFHxS) has been found in biological samples from
wildlife and humans. The geometric mean half-life of serum elimination of PFHxS
in humans has been estimated to be 7.3 years (95% CI 5.8-9.2 years). We undertook
a series of studies to establish pharmacokinetic parameters in non-human
species. Male (M) and female (F) monkeys were given a single intravenous (IV)
dose of K + PFHxS and serum and urine PFHxS concentrations were followed for
171 days. M and F rats were given single oral doses of 1, 10, or 100 mg/kg
K + PFHxS and urine and feces were collected over 96 hours and serum and liver collected
at 96 hours. Jugular-cannulated M and F rats were given either IV or oral
single 10 mg/kg doses of K + PFHxS and serum concentrations of PFHxS were followed
for 24 hours. M and F rats were given a single IV dose of 10 mg/kg, and
serum, feces, and urine were collected weekly for 10 weeks. All PFHxS analyses utilized
LC-MS/MS methods. Pharmacokinetic parameters were determined by
WinNonlin® software. Volumes of distribution indicated predominant extracellular
distribution. Mean serum elimination half-lives were 141 and 87 days for M and
F monkeys and ca. 30 and 1.5 days for M and F rats.
1586 THE EFFECT OF COLESEVELAM HYDROCHLORIDE
ON THE ELIMINATION OF POTASSIUM
PERFLUOROOCTANOATE (PFOA) FROM SERUM IN
MALE AND FEMALE CYNOMOLGUS MONKEYS.
D. J. Ehresman 1 , P. E. Noker 2 , G. W. Olsen 1 , L. R. Zobel 1 , S. Chang 1 and J. L.
Butenhoff 1 . 1 3M Company, St. Paul, MN and 2 Southern Research Institute,
Birmingham, AL.
Perfluorooctanoate (PFOA) is widely distributed in humans and wildlife. Due to its
slow elimination in humans (serum geometric mean half-life (T 1/2
)=3.5 yrs), this
study was to evaluate whether colesevelam hydrochloride (colesevelam HCl, an
anion-exchang resin compound that lowers lipids by impeding bile acid absorption
in the intestine), can affect the elimination of PFOA from serum in cynomolgus
monkeys. On study day (SD) 0, monkeys (N=3/sex/group, ~ 2 to 5 yrs old) received
a single intravenous dose of K + PFOA (10 mg/kg)in cephalic vein. On SD
21-27 and 56-83, daily oral doses of placebo (water) were given to Group 1 monkeys
while Group 2 monkeys received placebo on SD 21-55. On SD 28-55, daily
oral doses of colesevelam HCl (250 mg/kg-d) were given Group 1 monkeys while
Group 2 monkeys received colesevelam HCl on SD 56-83. Serum samples were
collected and analyzed for PFOA concentrations using LC/MS-MS from each
monkey prior to dosing (0 hr), on SD 0 (0.5 hr post iv dose), 7, 14, 21, 28, 35, 42,
49, 56, 63, 70, 77, and 84. All monkeys survived until the end of the study. There
were no clinically significantly abnormal observations noted and body weights were
comparable between dose groups in each sex during the study. In either male (M)
or female (F) monkeys, there was no apparent difference in mean serum PFOA levels
between Group 1 (given colesevelam HCl on SD 28-55) and Group 2 (given
colesevelam HCl on SD 56-83). PK parameters indicated similar mean overall
serum half-life (T 1/2
) and AUC values of PFOA in M monkeys in Group 1
(T 1/2
=18.8 days, AUC=1965 hrdμg/mL) and Group 2 (T 1/2
=17.0 days,
AUC=1716 hrdμg/mL); as well as in F monkeys in Group 1 (T 1/2
=26.3 days,
AUC=2869 hrdμg/mL) and Group 2 (T 1/2
=28.4 days, AUC=2192 hrdμg/mL).
Therefore, administration of colesevelam HCl had no therapeutically significant
impact on serum PFOA levels, serum PFOA half-life, or serum PFOA AUC levels
within the limits of the study design.
1587 ANALYTICAL METHOD VALIDATION OF N-BUTYL
GLYCIDYL ETHER IN CORN OIL.
J. W. Algaier 1 , D. M. Logan 1 , V. F. Ault 1 , O. L. Beverly 1 , A. Kazerooni 1 , B. M.
O’Brien 1 , P. J. Schebler 1 , R. K. Harris 1 , B. Jayaram 2 and C. S. Smith 2 . 1 Energy
and Life Sciences Division, Midwest Research Institute, Kansas City, MO and
2
National Toxicology Program, NIEHS, Research Triangle Park, NC.
The compound n-Butyl Glycidyl ether (nBGE) is a high production volume chemical
used in the production of epoxy resins. Epoxy resins are used in many commercial
industries such as construction, electronics manufacturing and coating application.
The ubiquitous presence of epoxy resins, and their components, in these
industries has lead to concern for worker exposure. For this reason, nBGE has been
selected for toxicological evaluation by the National Toxicology Program (NTP).
An analytical method was developed and validated for the analysis of nBGE in corn
oil to cover a dose formulation range of ~4.0 to ~100 mg/mL. Standards were prepared
by adding nBGE and the internal standard (IS), 1-undecene, to corn oil and
diluting the mixture with THF. The standards were analyzed using gas chromatography
(GC) with flame ionization detection (FID) equipped with a Restek RTX-
1701 (30 m x 0.53 mm I.D., 1.5-μm film thickness) column. The oven program
was 40 °C (1-min hold) to 140 °C at 5 °C per minute and then to 240 °C at 20
°C/min. The retention time was 12.4 min for nBGE and 13.0 min for the IS. The
method validation was linear (r ≥ 0.9999), accurate (from -0.8 to 0.9% relative
error), and precise (% RSD ≤ 0.5). Following method validation a 42-day dose formulation
stability study and a 3-hour simulated dosing study were performed at 10
mg/mL nBGE in corn oil. The 42-day dose formulations were stored under ambient
(25 °C) and refrigerated (5 °C) conditions. When compared to Day 0 values,
the results indicated losses ≤ 0.6% under ambient conditions and ≤ 1.1% under refrigerated
conditions. The 3-hour simulated dosing formulations were stored in
clear serum vials exposed to air and light under ambient (25 °C) temperature. When
compared to Day 0, the results indicated losses ≤ 0.6%. A high dose formulation of
~410 mg/mL nBGE in corn oil was evaluated for homogeneity and was shown to be
homogeneous based on with an observed RSD of 0.7% for n=9 samples.
1588 ANALYTICAL METHOD VALIDATION FOR THE
QUANTITATION OF SIX NITROSAMINES IN NTP-2000
RODENT FEED.
P. J. Schebler 1 , A. D. Ammenhauser 1 , J. L. Cookinham 1 , J. W. Algaier 1 , R. K.
Harris 1 , B. Jayaram 2 and C. S. Smith 2 . 1 Energy and Life Sciences Division, Midwest
Research Institute, Kansas City, MO and 2 National Toxicology Program, NIEHS,
Research Triangle Park, NC.
Nitrosamines, a class of compounds identified as potentially carcinogenic, are
found in beverages, nitrate cured foods and may be formed during cooking or food
processing. The presence of nitrosamines in specialized rodent diets used for toxicology
studies can potentially confound the interpretation of data from a toxicological
study. Thus, it is important to demonstrate that rodent diets used in these studies
are low in nitrosamines. To this end the National Toxicology Program has
sponsored the development and validation of a chromatographic method to quantitate
six nitrosamines (N-nitrosodimethylamine, N-nitrosodiethylamine, N-nitrosodibutylamine,
N-nitrosopiperidine, N-nitrosopyrrolidine, and N-nitrosomorpholine)
in NTP-2000 feed. Matrix standards covering a concentration range of
SOT 2010 ANNUAL MEETING 337