Evaluation of effect on central nervous system by FOB and cardiovascular system by telemetry for CPZ in dogs

Abstracts / Journal of Pharmacological and Toxicological Methods 60 (2009) 210–258

Comparison of pigmented and albino guinea pigs for use in ototoxicity modeling Rachel Tappa,⁎, Michael Eliela, David D. Dolanb, Richard A. Altschulerb, David V. Gauvina, Theodore J. Bairda a Safety Pharmacology & Neurobehavioral Sciences, MPI Research, Mattawan, MI, United States b KHRI, University of Michigan, Ann Arbor, MI, United States Introduction: Ototoxicity evaluation is a supplemental safety assay among the many requisite investigations that identify and characterize the potential neurotoxic effects of new chemical entities and consumer products. Questions as to the value of utilizing pigmented (outbred) versus albino (inbred) strains of animals for these studies, and when considering alternate routes of drug administration (i.e. intra-aural) remain prominent in the present regulatory environment. Data obtained from safety investigations performed at MPI Research are compared to evaluate auditory system status of pigmented and albino guinea pigs and influences of surgical versus non-surgical routes of aural administration. Methods: Pigmented guinea pigs were surgically implanted with an indwelling catheter into the bulla and administered normal saline for 14 days (b.i.d.). Albino animals were administered normal saline via the outer ear canal for 14 days (b.i.d.). Auditory Brainstem Responses (ABRs) were completed pre-study and prior to termination and inner ear structures were evaluated via cytocochleogram. Results: Baseline ABRs showed no difference between pigmented or albino animals from different breeding laboratories. Four pigmented, and 5 albino animals, respectively, were excluded from study due to hearing loss or suspected cochlear abnormalities at baseline. Terminal ABRs and cytocochleograms showed no differences as a function of chronic bullar catheterization and dosing.

doi:10.1016/j.vascn.2009.04.094

Evaluation of dose, time, and frequency dependent ototoxic response to cisplatin administration in the albino guinea pig Theodore J. Bairda,⁎, Jeffrey W.-D. Foyb, David D. Dolanc, Theron Walla, Tara Posthumusa, Michael Eliela, Rachel L. Tappa, David V. Gauvina a Safety Pharmacology & Neurobehavioral Sciences, MPI Research, Mattawan, MI, United States b Quark Pharmaceuticals, Boulder, CO, United States c KHRI, University of Michigan, Ann Arbor, MI, United States The sensitivity of the auditory system to topically applied agents may be observed as patterns of change in functional electrophysiological measures and/or neurohistopathological features. However, systemically administered pharmacotherapeutics with various indications, from antibiotics to anticancer drugs, also have certain risk for producing such effects at doses that are at or near efficacious dose levels. The systemic and ototoxicity of platinum-based chemotherapeutic agents and other metals have been described under a variety of treatment paradigms including varying doses, times, and routes of administration, and in various species. From such prior investigations, the relation of these variables to specific indicators of systemic and ototoxicity are unclear. The present experiment was conducted to definitively establish dose- and time-effect relationships between cisplatin exposure and functional indices of ototoxicity in the guinea pig, while minimizing nephrotoxicity or other complications related to systemic toxicity. Results indicate a threshold effect of cisplatin on functional hearing loss, as well as an acute phase response, with residual ABR threshold shift that is in proportion to cumulative

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cisplatin dose. The implications of these data to the modeling of auditory dysfunction are discussed.

doi:10.1016/j.vascn.2009.04.095

A primary “ICH S7A CNS CORE” neurobehavioral screen for early phase drug discovery Donald B. Hodges Jr. Vertex Pharmaceuticals, Cambridge, MA, United States To reduce overall expense in the drug discovery process, it is important to identify possible safety concerns for new chemical entities (NCE) as early as possible. The role of Safety Pharmacology in early phase drug discovery is to provide a perspective of potential risk, identify follow-up evaluations to improve risk assessment and make this information meaningful to all involved in the discovery process. We have developed a rat Functional Observation Battery (FOB) based on the SHIRPA mouse FOB model as a primary neurobehavioral screen. A secondary test for catalepsy was included in the rat FOB. The rat FOB was designed to characterize the acute effects on centrally-mediated behaviors/activities of NCE. The FOB has 55 measures which were completed 10 min per subject. The doses tested in the FOB were vehicle, 1, 5 and 10 times NCE effective dose (n = 6/group). Only a single time point was measured based on the time needed for the NCE to reach maximum brain concentration. Subjective measures were analyzed using the Kruskal–Wallis one-way analysis of variance by ranks. Objective measures were analyzed by one way ANOVA. Measures having significant treatment effects (p ≤ 0.10) were divided into five categories: Muscle and Lower Motor Neuron, Spinocerebellar, Sensory, Neuropsychiatric, and Autonomic functions. Total scores were shown as the sum of the measures in each category. The measures having significant treatment effects, the five categories, and total scores were presented in a table. Data (mean ± sem) for these measures were also presented in a bar graph. Validation studies with diazepam, d-amphetamine, oxotremorine, haloperidol, and morphine showed this method to be effective for profiling NCE and for providing interpretive results to those not familiar with neurobehavioral data. doi:10.1016/j.vascn.2009.04.096

Evaluation of effect on central nervous system by FOB and cardiovascular system by telemetry for CPZ in dogs Kiyotaka Hoshiai Kobuchisawa Research Laboratory, Fuji Biomedix, Kobuchisawa, Hokuto, Yamanashi, Japan Safety pharmacological studies by the functional observational battery (FOB) have been performed in rats. However, it is important to carry out FOB in dogs, because dogs are more approximate to humans for the metabolic pathway of a drug. For the evaluation of safety of a drug, it will add more information to perform telemetric measurement at same time with FOB. It became possible to carry out FOB in dogs in our facilities. Then, the correlation of data between rat and dog was examined. Whether it is possible to carry out at same time the evaluation of cardiovascular effect by the telemetry was also examined. Four male beagles, which were implanted a transmitter for telemetry, were orally administered chlorpromazine (CPZ) at 0, 3, 10 and 30 mg/kg, and the reaction was measured by FOB and telemetry. CPZ 30 mg/kg group showed a tendency of decreases in respiratory rate, threat reaction, auditory response, sense of pain reaction, subdivision-transferring number, earring count, spontaneous beha-

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Abstracts / Journal of Pharmacological and Toxicological Methods 60 (2009) 210–258

vior, reaction in bending forelimb/hind leg and body temperature. Additionally observed were vomiting, tremor, abnormal behavior, miosis, hyperemia of the visible mucosa. Heart rate tended to increase, but the effect on blood pressure could not be recognized. From the above-mentioned results, CPZ 30 mg/kg administration influenced the central nervous system. For the cardiovascular system, it had effect on heart rate, but without influence on blood pressure. In this experiment, it was possible to evaluate effect of the drug on the central nervous system and cardiovascular system in the dogs. doi:10.1016/j.vascn.2009.04.097

detecting functional motor loss depending on the endpoint assessed. For TMPD and the Lilly compound, hind limb grip strength was the most sensitive assay for detecting functional motor loss while rotarod was the least sensitive. Although clinical observations were more sensitive than rotarod and inverted screen tests, they proved to be the most time consuming and laborious. For imipramine, a compound known to produce general ataxia, grip strength and inverted screen were equally sensitive for detecting functional motor changes. These data suggest that hind limb grip strength is the most appropriate assay for detecting functional changes that precede muscle necrosis. doi:10.1016/j.vascn.2009.04.099

Short-term EEG recording in conscious Göttingen minipigs as an alternative to non-human primates and dogs ⁎

Mark Vezina , A. Patel, S. Wise Charles River Laboratories Preclinical Services Montreal, Quebec, Canada Recording an electroencephalogram (EEG) from different species in the conscious state presents different challenges. While acclimation to restraint is necessary for all species, the non-human primate requires additional restraint and the dog tends to have a lower seizure threshold for many compounds. The minipig was investigated as an alternative non-rodent species based on its trainability for restraint and easy access for electrode placement. Animals were acclimated to restraint in a sling, prior to recording baseline EEGs. Subcutaneous needle electrodes were configured to record the approximate equivalents of bipolar leads fz-cz, cz-t2 and o1-o2, covering the frontal temporal and occipital regions. EEGs were recorded for 10-minute epochs at least twice for baseline evaluation through a BioPac MP150 system. Baseline measurements revealed fewer movement artifacts compared to monkeys and dogs. The incidence of spontaneous sharp waves was low. Following baseline recording the animals received incremental intravenous doses of pentylenetetrazol (PTZ) at sub-seizure doses, clearly demonstrating that the model can detect pre-seizure activity with a known proconvulsant compound. It was determined that the conscious minipig was a suitable alternative to dogs and monkeys for shortterm recording of the EEG, using needle electrodes, for seizure liability evaluations. doi:10.1016/j.vascn.2009.04.098

Functional motor assessments associated with skeletal muscle necrosis CHAR(13) + CHAR(10) Mary Jeanne Kallman⁎, Deah Modlin, Mario Sgro Eli Lilly and Co., Greenfield, IN, United States The purpose of these studies was to identify sensitive and appropriate assays for detecting motor deficits associated with skeletal muscle necrosis and evaluate dose-responsive functional data to provide correlates for biomarker and pathology changes and assess the functional relevance of those alterations. Therefore, multiple behavioral assays for assessing functional motor loss were characterized in male rats. Male Sprague Dawley rats (n = 10/dose group) were evaluated using clinical observation, inverted screen test, rotarod and grip strength assays following oral administration of 7 or 9 mg/kg 2,3,5,6-tetramethyl p-phenylenediamine (TMPD), 30, 100 and 300 mg/kg imipramine or 100, 300 and 1000 mg/kg of a Lilly compound known to produce skeletal muscle necrosis. Results from these evaluations indicate different levels of sensitivity for

Can locomotor screening be utilized as a first-tiered approach for pre-clinical CNS/neurobehavioral safety testing? James J. Lynch III⁎, Scott W. Mittelstadt Department of Integrative Pharmacology, Abbott Laboratories, Abbott Park, IL, United States During the pharmaceutical discovery process, a tiered approach is necessary for the pre-clinical testing of compounds in order to maintain sufficient throughput. For central nervous system (CNS)/neurobehavioral safety pharmacology testing, the locomotor assay has advantages as an initial screen due to its automation, quantitative results, and relatively low level of training required to perform the assay. The current study was conducted to compare results from a spontaneous locomotor activity assay to results from 3 other CNS/neurobehavioral safety assays to determine the predictability of the former for the latter data. Mouse and rat data from a broad range of sufficiently-tested, pre-clinical target compounds were examined. For all 11 of the compounds found to have moderate to severe neurobehavioral effects in the Irwin (primary observation) test, all 6 of the compounds with statistically significant increases in sleep duration in the ethanol interaction test, and 7 of the 8 compounds with significant pro-convulsant activity in the pentylenetetrazole seizure test, significant changes in locomotor activity (mainly decreases) were detected within 10-fold of the lowest doses having effects in the non-locomotor assays. We conclude that changes in spontaneous locomotor activity are excellent indicators of potential primary observational effects, ethanol interaction (sleep induction), and pro-convulsant activity of test compounds in rodents, therefore suggesting the utility of a locomotor assay for the first-tiered screening of pre-clinical candidate compounds for CNS safety. doi:10.1016/j.vascn.2009.04.100

Evaluation of propofol effect in altering pentylenetetrazol induced seizure threshold in peripheral inflammatory models in rats Bikash Medhi⁎, Ajay Prakash, Prasad Byrav D S. Department of Pharmacology, PGIMER, Chandigarh, India Purpose: To evaluate the role of propofol in altering pentylenetetrazol induced seizure threshold in peripheral inflammatory models in rats and its antagonist effect by thalidomide. Materials and methods: Total 42 Wister rats of either sex were included in the study. Animals were divided into seven groups (n=6) control group (PTZ, 60 mg/kg), PTZ low dose group (40 mg/kg), propofol (5 mg/kg), propofol (5 mg/kg) + PTZ (40 mg/kg). TNBS induced colitis group (PTZ 40 mg/kg), TNBS colitis+propofol (5 mg/kg)+PTZ (40 mg/kg) and TNBS colitis+propofol (5 mg/kg)+PTZ (40 mg/kg) and