Relative equivalence of CNS safety (FOB) assessment outcomes in male and female Wistar-Han and Sprague-Dawley rats.

In 2006 the National Toxicology Program (NTP) of the FDA shifted to the preferred use of Wistar-Han rats from the more commonly used Sprague-Dawley (SD) strain - and industry followed. While European laboratories preferred the Wistar-Han line, there was a paucity of relevant historical control data in many US research institutions for the new "industry standard" rat strain. In 2010 the NTP reversed its decision and shifted back to SD rats because of reproductive issues with the Wistar strain. For post hoc comparative analyses, we report minimal practical differences in Functional Observational Battery (FOB) data from a large sample of male and female Wistar-Han and SD rats. In summarizing data from the preclinical safety evaluations of the CNS effects of new drugs using the FOB, it is crucial to understand the value of not only how the functional expression of drug effects in the rat are predictive of the human response, but also how and why they differ. What we can predict from the behavioral and physiological response of the designated test system to drug administration is the foundation of "generalizability" to the human's response. Here, we conclude that the use of either SD or WH rat strains in standard CNS safety studies provide equivalent supportive data for CNS safety assessment required for IND approval under the harmonized guidelines.

A predictive index of biomarkers for ictogenesis from tier I safety pharmacology testing that may warrant tier II EEG studies.

Three significant contributions to the field of safety pharmacology were recently published detailing the use of electroencephalography (EEG) by telemetry in a critical role in the successful evaluation of a compound during drug development (1] Authier, Delatte, Kallman, Stevens & Markgraf; JPTM 2016; 81:274-285; 2] Accardi, Pugsley, Forster, Troncy, Huang & Authier; JPTM; 81: 47-59; 3] Bassett, Troncy, Pouliot, Paquette, Ascaha, & Authier; JPTM 2016; 70: 230-240). These authors present a convincing case for monitoring neocortical biopotential waveforms (EEG, ECoG, etc) during preclinical toxicology studies as an opportunity for early identification of a central nervous system (CNS) risk during Investigational New Drug (IND) Enabling Studies. This review is about "ictogenesis" not "epileptogenesis". It is intended to characterize overt behavioral and physiological changes suggestive of drug-induced neurotoxicity/ictogenesis in experimental animals during Tier 1 safety pharmacology testing, prior to first dose administration in man. It is the presence of these predictive or comorbid biomarkers expressed during the requisite conduct of daily clinical or cage side observations, and in early ICH S7A Tier I CNS, pulmonary and cardiovascular safety study designs that should initiate an early conversation regarding Tier II inclusion of EEG monitoring. We conclude that there is no single definitive clinical marker for seizure liability but plasma exposures might add to set proper safety margins when clinical convulsions are observed. Even the observation of a study-related full tonic-clonic convulsion does not establish solid ground to require the financial and temporal investment of a full EEG study under the current regulatory standards. PREFATORY NOTE: For purposes of this review, we have adopted the FDA term "sponsor" as it refers to any person who takes the responsibility for and initiates a nonclinical investigations of new molecular entities; FDA uses the term "sponsor" primarily in relation to investigational new drug application submissions.

The standardized functional observational battery: Its intrinsic value remains in the instrument of measure: The rat.

The International Conference on Harmonisation's (ICH) Tripartite Guideline on Safety Pharmacology Studies for Human Pharmaceuticals has adopted the requirement that each new test substance must be tested for effects on the central nervous system prior to "first dose in man". This assessment is required to measure, at a minimum, the effects of the substance on general motor activity, behavioral changes, coordination, sensory/motor reflex responses, and body temperatures. To achieve this goal, ICH S7A recommends a neurobehavioral assessment (usually a functional observational battery (FOB) or modified Irwin test), which is generally undertaken in the rat. There seems to be a growing lack of consensus on the value of the FOB to determine CNS safety. This review highlights the importance of the time, effort and cost of training technicians to familiarize with their instrument of measure, so that each observer is better able to identify and document very subtle changes in behavior that will serve to increase the reliability and validity of these assays with respect to CNS safety assessments.

Instilled or injected purified natural capsaicin has no adverse effects on rat hindlimb sensory-motor behavior or osteotomy repair.

BACKGROUND: A novel formulation of > or = 98% pure capsaicin (4975) is currently undergoing clinical investigation using novel routes of delivery to provide selective analgesia lasting weeks to months with a single dose. We conducted this study to assess the safety and effects of instilled and injected 4975 in rat models of wound healing osteotomy repair and sensory-motor nerve function. METHODS: Adult male and female Sprague-Dawley rats were used. To assess the effects of 4975 on nerve or muscle, 0.0083 or 0.025 mg 4975 or vehicle (25% polyethylene glycol-300) was applied to exposed sciatic nerve, or 0.1 mg 4975 or vehicle was injected into the surrounding muscle (Group 1). To assess the effect of 4975 on bone healing, an osteotomy was made in one femur and 0.5 mg of 4975 or vehicle was instilled into the site (Group 2). Behavioral testing was performed on both groups of rats and histological evaluation of the sciatic nerve, and surrounding soft tissue and bone was done at days 3, 14, and 28 after surgery. Femurs from osteotomy rats were assessed using peripheral quantitative computed tomography and biomechanical testing. Standard statistical tests were used to compare groups. RESULTS: Rats with direct application of 4975 to the sciatic nerve and surrounding muscle were no different from the controls in nociceptive sensory responses (F = 0.910, P = 0.454), grip strength (F = 0.550, P = 0.654), or histology of the muscle or sciatic nerve. In osteotomy rats, there were no statistical differences between 4975 and vehicle-treated rats for bone area (H = 2.858, P = 0.414), bone mineral content (F = 0.945, P = 0.425), or bone mineral density (F = 0.87, P = 0.462) and no difference in soft tissue healing. There were neither differences in bone stiffness (F = 1.369, P = 0.268) nor were there noticeable differences in the macro- or microscopic appearance of the right femur osteotomy healing site and surrounding soft tissues between the control group and the 4975-treated animals. CONCLUSION: A single, clinically relevant application of instilled or injected 4975 has no observable adverse effect on wound and bone healing after osteotomy or on the structural integrity of exposed muscle and nerve.

Animal reuse: balancing scientific integrity and animal welfare.

Research scientists and IACUC members are faced with the difficult task of balancing the necessity of using animals for experimental research and their mandate to protect the welfare of those animals used in that research. One way to reduce the number of research animals would be to reuse them, but the regulations do not specifically address this topic. To learn more about the reuse of research animals, the authors conducted an online survey of animal facilities involved in preclinical studies. Their results suggest that animal reuse is a common practice in the field.