The Toxicologist - Society of Toxicology

1914 VALIDATION OF RESPIRATORY INDUCTANCE
PLETHYSMOGRAPHY IN CONSCIOUS CYNOMOLGUS
MONKEYS.
K. R. Kearney, M. R. Metea and P. R. Atterson. WIL Research Laboratories, LLC,
Ashland, OH.
Non-invasive systems for acquisition of respiratory data are increasingly used for
preclinical studies. Such systems allow for acquisition of respiratory data within
standard toxicology study designs, to provide additional endpoints.
The aim of this study was to assess the feasibility of using respiratory inductance
plethysmography (RIP) for continuous respiratory data collection from ambulatory
animals, develop accurate calibration methodology and animal acclimation procedures.
Methods: Three male and three female cynomolgus monkeys were acclimated
to LOMIR infusion jackets and restraint chairs equipped with a helmet system
including pneumotachograph (PNT) on 5 separate occasions. The RIP data
were calibrated using known volumes derived from helmet and the PNT system.
Following calibration of the RIP band system, animals were challenged with morphine
and amphetamine at 5, 1 mg/kg, respectively, according to a crossover design.
Respiratory data (frequency, tidal volume, and minute volume) were continuously
collected for up to 24 hours. Respiratory parameters were analyzed with a repeated
measure analysis of covariance to determine the sensitivity of the method in detecting
respiratory changes. Multiple calibrations were performed using the PNT to develop
accurate calibration procedures and determine drift of RIP signal over time.
Results: Respiratory changes elicited with the reference compounds were detected
with statistical analysis and followed the known time course of the drugs. RIP calibrations
before and after the collection were comparable indicating that the drift
was minimal over long term collections. Minimal acclimation of animals was determined
to be 5 periods of restraint to the PNT collection system and 3 periods of
jacket acclimation.
1915 DRUG DISPOSITION AND CARDIAC TOXICITY: A
LITERATURE-BASED REVIEW.
T. G. Hammond 1 , J. Bowes 1 , S. Boyer 3 , M. P. Burnham 1 , D. Cook 1 , C.
Gavaghan 3 , M. Hance 4 , M. M. Haywood 1 , S. Matis 4 , S. Roberts 1 , B.
Springthorpe 2 and J. Valentin 1 . 1 Safety Assessment, AstraZeneca, Alderley Park,
United Kingdom, 2 Safety Assessment, Astrazeneca, Charnwood, United Kingdom,
3 Safety Assessment, Astrazeneca, Molndal, Sweden and 4 Safety Assessment,
Astrazeneca, Wilmington, DE.
Cardiovascular safety liabilities remain a major cause of: drug attrition during preclinical
and clinical development; adverse drug reactions; and withdrawal of medicines
from the market. However, only a small proportion of these withdrawals are
due to arrhythmias (~27% of 154 drugs). Compounds associated with cardiovascular
toxicities show structural diversity that overlaps most of the “drug-like” space;
therefore there is a need to look at potential mechanisms underpinning such toxicities.
Bio-informatics and text-mining tools, enabling a thorough review of the literature,
were used to assess the current situation. Cardiac accumulation of drugs,
transporters and metabolising enzymes were found to have potential importance in
cardiac drug toxicity. Many transporters (n=127) and P450s (n=14) are expressed,
some selectively, in the heart; some of which are reported to transport (n=12) or
metabolise (n=12) xenobiotics. Conversely, some drugs associated with cardiovascular
toxicities are either transported (n=6) or metabolised (n=6) by these transporters
/ P450s, respectively. Most of these transporters and P450s have unknown
functions in the heart; although genetic studies indicate that some have the potential
to produce detrimental cardiovascular toxicities. Furthermore, the potential for
drug-drug interactions exist but as yet these are unknown. Further research should
be encouraged to understand the full impact of such observations.
1916 POLYSORBATE 80 14.7% IS A SUITABLE VEHICLE IN
LONG-TERM NON-HUMAN PRIMATE TOXICOLOGY
STUDIES.
M. Awori 1 , E. Lesage 1 , F. Vlasseros 1 , S. Y. Smith 1 , T. Ahn 2 and K. Veverka 2 .
1 Toxicology, Charles River Preclinical Services, Montreal, QC, Canada and 2 GTx,
Inc., Memphis, TN. Sponsor: M. Vézina.
Polysorbate 80 (PS80) is a surfactant and emulsifier used in foods and in the manufacture
of some medications for parenteral administration. PS80 is also a commonly
used vehicle in preclinical toxicology studies. However, historical data on the
use of PS80 in long-term non human primate studies is limited. The FDA Inactive
Ingredients Database lists the maximum potency for oral suspensions of PS80 as
12.5%. PS80 is frequently used at concentrations up to 1.0% (w/w) in oral toxicology
studies. The objective of this study was to evaluate the safety and tolerability of
daily oral administration of 14.7% (v/v) PS80 for up to 39 weeks in cynomolgus
monkeys, a longer duration than has been previously documented in this species.
410 SOT 2011 ANNUAL MEETING
PS80 was diluted in PRANG solution to prepare a concentration of 14.7%
which was administered orally (cage side dosing) daily for 39 weeks to 10 male
monkeys aged between 5 and 6 years old and weighing between 5.8 and 8.1 kg at
the start of dosing. Animals were dosed at a dose volume of 4 mL/kg/day, 633
mg/kg/day, for the first 23 weeks and at 5 mL/kg/day, 792 mg/kg/day, for the remainder
of the dosing period. Five monkeys were dosed for 13 weeks, of which 3
were euthanized, and 5 monkeys were dosed for 39 weeks of which 3 were euthanized,
with the remaining animals retained untreated and euthanized after 4 weeks
recovery. The administration of 14.7% PS80 during a period of 13 or 39 weeks was
not associated with any clinical signs or effects on appetence, body weights, ophthalmology,
electrocardiography, clinical pathology and histopathology. Based on
these data, oral administration of Polysorbate 80 was considered to be non toxic at
a concentration of 14.7% when administered daily to male monkeys for up to 39
weeks and is considered a suitable vehicle for use in long-term non human primate
toxicology studies.
1917 BACKGROUND DATA AND COMPARISON OF TWO
LONG-TERM CONTINUOUS INTRAVENOUS
INFUSION MODELS IN THE MOUSE USED FOR
SAFETY ASSESSMENT STUDIES.
H. Van Wijk and A. Fraser. Covance Laboratories Ltd., Harrogate, United Kingdom.
Sponsor: S. Kirk.
The need for improvements in the development of long term vascular infusion systems
for rodents continues to increase. The mouse is proving a viable alternative to
the rat but there is little published background data. This poster presents data on
the comparison of two different techniques. Two continuous intravenous infusion
techniques were conducted involving catheterisation of the vena cava via the
femoral vein with different points of exteriorisation. The tail cuff technique, in
which the catheter exteriorises via the tail stabilised by a tail cuff, was found to be
appropriate for studies up to 28 days. However, for longer term studies a different
continuous infusion model is needed and so the harness method was developed in
which the catheter exteriorises via the dorsum, stabilised by a harness and skin button.
Two 14 day and a 28 day tail cuff studies and a 91 day harness/skin button
study (with a 7 day interim kill) were conducted. Data from these studies, including
surgical success rates, reliability of the infusion method, bodyweights, clinical
and behavioural observations, ophthalmoscopy, clinical pathology and histopathology
were collected for comparison. For the tail cuff method, the reliability was
87.6% up to 14 days which dropped to 74% by 28 days due to pathology around
the tail cuff. In terms of animal welfare, the tail cuff method allowed freedom of
movement around the cage and normal sleeping patterns compared to the more restrictive
harness/skin button method. The harness/skin button method was less reliable,
mainly due to problems of securing the harness on the mouse. In addition,
exophthalmos due to compression of the anterior tissues of the animals by the harness
caused a keratitis in 75% of terminal kill animals. In conclusion, the tail cuff
method is considered to be a reliable method for studies up to 28 days and acceptable
with respect to animal welfare. After 28 days the harness/skin button method
developed in this study is not yet considered to be a reliable alternative due to problems
associated with the harness itself.
1918 INTEGRATION OF PIG-A, MICRONUCLEUS,
CHROMOSOME ABERRATION, AND COMET ASSAY
ENDPOINTS IN A 28-DAY RODENT TOXICITY STUDY
WITH 4-NITROQUINOLINE-1-OXIDE (4NQO).
M. McKeon, H. Chen, T. E. Lawlor, H. Murli, D. J. Roberts, A. Thakur, Y.
Xu and L. F. Stankowski. Covance Laboratories, Inc., Vienna, VA.
As part of a multi-lab validation, we examined induction of Pig-a mutant red blood
cells (RBCs) and reticulocytes (RETs) by flow cytometry during a 28-day subchronic
toxicity study in male Sprague-Dawley rats using 4NQO (1.25, 2.50, 3.75,
5.00 and 7.50 mg/kg/day by oral gavage). Also evaluated were micronucleated
RETs (mnRETs); blood, liver, and stomach DNA damage using the comet assay;
and chromosome aberrations in peripheral blood lymphocytes. All genotoxicity
endpoints were analyzed at two or more timepoints where possible. Mortality, body
weight, food consumption, clinical pathology and organ weights also were analyzed,
since this study was intended to evaluate integration of the genotoxicity endpoints
into a standard 28-day toxicity study. Animals were sacrificed at Day 29, except
those dosed at 7.50 mg/kg/day, which were sacrificed early (Day 15) due to
extreme weight loss and morbidity/mortality. Dose-dependent body weight loss
and/or decreased body weight gain reached significance (p< 0.05) at 5.00 and 7.50
mg/kg/day by Day 6 or 5, respectively. Observations at sacrifice included: de-