The Toxicologist - Society of Toxicology

veloping animals to adverse effects of HBCD. This abstract does not reflect U.S.
EPA, USDA, and NCI/NIEHS policies. Supported by NIH Training Grant T32-
ES07126 and U.S. EPA CR833237.
1575 BUPRENORPHINE MODULATES
METHAMPHETAMINE-INDUCED EXTRACELLULAR
DOPAMINE RELEASE IN THE RAT CAUDATE-PUTAMEN.
B. Gough, S. Ali and Z. Binienda. Neurotoxicology, U.S. FDA/NCTR, Jefferson, AR.
The instrumental use of a stimulant, methamphetamine (METH), for functional
enhancement often leads to dependency. Oxidative stress mediates to a large extent
METH-evoked neurotoxicity. Clinical trials are being conducted to identify pharmacotherapeutic
adjuncts to behavioral therapy in the treatment of METH dependence.
Efficacy of the adjunctive medication with opioid compound, buprenorphine
(BUP), has been demonstrated in the treatment of opiate and cocaine
dependence. Here, we examined the effects of a dopaminergic response to a combined
METH/BUP treatment in the rat striatum. In vivo microdialysis and high
performance liquid chromatography with electrochemical detection (HPLC-EC)
were used to measure baseline and METH-stimulated striatal dopamine (DA) and
its metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) levels in adult male
Sprague-Dawley rats. Animals received either 2 mg/kg METH, i.p. or BUP at 0.01
or 10 mg/kg, s.c. alone 10 min before 2 mg/kg METH. Dialysates were assayed
every 20 min for 300 min following METH administration. Compared with baseline
(100%), a sharp DA increase to 1090 ± 175% was observed after METH treatment.
While treatment with 0.01 and 10 mg/kg BUP alone did not alter DA levels,
rats treated with METH and 0.01 or 10 mg/kg BUP exhibited an extracellular increase
in DA of 439 ± 90% and 639 ± 55%, respectively. The duration of the DA
response and the area under the curve were attenuated as well. Although DOPAC
levels didn’t change from baseline following 0.01 mg/kg BUP (BUP0.01), the concentration
of DOPAC was significantly lower after the combined METH/
BUP0.01 treatment throughout the experiment. On the other hand, extracellular
DOPAC levels increased (p < 0.05) within 140 min following treatment with 10
mg/kg BUP (BUP10). METH/BUP10 treatment induced a decrease in the
DOPAC levels that lasted for 150 min. Data indicate that BUP modulates the DA
response to a METH challenge and may suggest effectiveness of low-dose BUP
treatment in METH addiction.
1576 TOXICOKINETICS OF RESVERATROL IN MALE,
FEMALE, PREGNANT, AND LACTATING WISTAR
HAN RATS.
T. Fennell 1 , N. L. Gaudette 1 , B. L. Fletcher 1 , S. D. Cooper 1 , M. Silinski 1 , J.
Blake 1 , F. Thomas 1 , R. Fernando 1 and B. J. Collins 2 . 1 RTI International, Research
Triangle Park, NC and 2 NIEHS, National Toxicology Program, Research Triangle
Park, NC.
Resveratrol, a polyphenol found in plants such as grapes and peanuts, has been reported
to have antioxidant and cardioprotective effects. Widespread public exposure
to resveratrol in diet or supplements has raised concern about potential toxicity.
This study was conducted to measure resveratrol in plasma, fetuses and pups at
doses proposed for toxicity testing in rats. A single dose of trans-resveratrol was administered
p.o.(78 and 1250 mg/kg) to male and female Wistar Han rats.
Resveratrol was also administered daily to pregnant Wistar Han rats from gestation
day (gd) 11 – 18, or gd 18 - post natal day (pnd) 3 (78 and 1250 mg/kg/day).
Blood, fetuses and pups were collected at 15, 30, 60, 90 min, 4 and 8 hr following
the last dose from one rat or dam per timepoint. Resveratrol in adult plasma was
measured by UPLC-PDA, and in fetal or pup homogenate by LC-MS/MS for noncompartmental
pharmacokinetic analysis. Plasma concentrations ranged from
〈LOQ (10.2 ng/mL) - 1340 ng/mL. The elimination half-life (t 1 ⁄ 2) of resveratrol in
male rats was 323 and 395 min at the low and high dose respectively, compared
with 168 and 609 min in female rats. AUC increased in a less than dose proportionate
manner in male rats. In pregnant rats (gd 11-18), t 1 ⁄ 2 was 88 min at the low
dose, and 1210 min at the high dose. The increase in AUC was greater than proportional
to dose, implying saturation of metabolism. In pregnant/lactating rats (gd
18-pnd 3), t 1 ⁄ 2 was 37 min at the low dose, and 148 min after the high dose. The
highest plasma concentrations were observed in the high dose pregnant/lactating
group (1340 ng/mL). At gd 18, AUC was similar in maternal plasma and fetal tissue,
but on pnd 3, AUC in pups was 6-7 fold higher than in maternal plasma. This
study established plasma resveratrol concentrations expected during toxicity testing
in pregnant and lactating rats, and indicated that resveratrol is transferred to the
fetus in pregnancy and to the pup by lactation.
1577 PRECLINICAL SAFETY ASSESSMENT OF A NEW
ANTITHROMBOTIC DRUG, THE NANOBODY®
ALX-0081.
S. Jacobs 1 , H. Ulrichts 1 , S. Priem 1 , S. Rossenu 1 , P. Stanssens 1 , J. Leuschner 2 , J.
Baumeister 1 and J. Holz 1 . 1 Ablynx, Zwijnaarde, Belgium and 2 LPT, Hamburg,
Germany. Sponsor: V. Chen.
Ablynx develops antibody-derived therapeutic proteins, Nanobodies®, for the use
in patients affected by various diseases including cardiovascular, bone and inflammatory.
They are based on the smallest functional fragments of heavy chain antibodies,
which occur naturally in the Camelidae family. ALX-0081, a bivalent
Nanobody® manufactured in E.coli, targets the platelet adhesive von Willebrand
Factor (vWF). It is formulated for i.v. (drug product: ALX-0081) or s.c. administration
(drug product: ALX-0681). ALX-0681 and ALX-0081 are currently in clinical
development PhI and PhII respectively. ALX-0081 specifically blocks interaction
of the A1-domain in regular sized and ultra-large vWF multimer with the
platelet receptor GPIb-IX-V. Therefore, this compound could be a powerful inhibitor
of the pathophysiology of thrombotic events in several diseases e.g. ACS
and TTP. Cynomolgus monkey and guinea pig were identified as the appropriate
species for safety assessment. This was confirmed via tissue cross-reactivity staining,
in vitro binding/competition and efficacy assays and in vivo PK/PD measurements.
The toxicology program includes single dose and repeated dose toxicity studies in
both species and an embryo-fetal developmental study in guinea pig. Safety pharmacology,
fertility testing and local tolerance are incorporated in the repeated dose
studies. Maximum target saturation was anticipated in the design and dosing
schemes were guided by a mechanistic PK model describing clearance mechanisms
and drug-target relationships of ALX-0081. ALX-0081 exhibits no sign of adverse
effects in both species so far due to (i) a unique PK behavior where only drug
bound to the target vWF is retained in circulation and excess drug is rapidly eliminated,
(ii) a lack of secondary pharmacology and (iii) a mode of action highly specific
for pathological events. The sole treatment-related effect noted was a decrease
in FVIII and vWF, which can be attributed to the pharmacology of ALX-0081 as
vWF serves as a carrier for FVIII.
1578 TOXICOKINETICS OF PERFLUOROOCTANOIC ACID
(PFOA) AND PERFLUOROOCTANE SULFONATE (PFOS)
USING MALE SPRAGUE-DAWLEY RATS AND
AUTOMATED DOSING/SAMPLE COLLECTION
INSTRUMENTS (EMPIS/CULEX).
S. Gibbs 1 , V. Godfrey 2 , S. Hong 1 , J. D. Johnson 1 , B. L. Burback 1 , S. W.
Graves 1 and C. Smith 2 . 1 Battelle Memorial, Columbus, OH and 2 NIEHS, NIH,
Research Triangle Park, NC.
PFOA and PFOS are considered global contaminants due to detection in humans
and wildlife in various geographical locations. This study determined plasma concentrations
for estimation of TK parameters of PFOA and PFOS and examined the
effect of co-administration of PFOA and PFOS. Three rats were given a single IV
administration of either 6.0 mg/kg PFOA, 2.0 mg/kg PFOS, or 6.0 mg/kg PFOA
co-mixed with 2.0 mg/kg PFOS in 2% Tween 80 in deionized water, delivered by
the automated dosing instrument (Empis). The dosing volume was 4 mL/kg. Blood
samples were collected by the automated sampling collection instrument (Culex).
The plasma samples were separated and analyzed by LC-MS/MS. The use of the
Empis/Culex significantly reduced the number of animals on study by allowing
sample collections from each rat to construct a complete TK profile. Both PFOA
and PFOS plasma concentration time profiles for the rats exhibited a biphasic decline,
which supported the use of a two-compartment model with first order elimination.
PFOA and PFOS exhibited similar TK parameter values when considering
variability associated with group mean values. PFOA and PFOS had long elimination
phases. The beta half-life values for PFOA were 6.89 and 3.08 days and for
PFOS were 5.74 and 2.22 days, alone and co-mixed, respectively. Whether PFOA
and PFOS were administered alone or together the TK parameter estimates did not
substantially change, thereby demonstrating the feasibility of conducting TK studies
on PFOA and PFOS as a co-mixture. The results of this study were used to design
a preliminary toxicokinetic study in order to correlate toxic effects with systemic
availability and to evaluate the feasibility of this automated approach for
future studies. [Supported by NIH, N01-ES-55551]
SOT 2010 ANNUAL MEETING 335