Variability of non-clinical behavioral CNS safety assessment: An intercompany comparison.

INTRODUCTION: Irwin/FOB testing is routinely conducted to investigate the neurofunctional integrity of laboratory animals during preclinical development of new drugs, however, the study design frequently varies to meet specific needs. Representatives of several European-based pharmaceutical companies performed a "state-of-the-art" assessment of how they conduct their CNS safety evaluation using Irwin/FOB tests. METHODS: This assessment consisted of (1) a survey of current/historical practice, (2) an evaluation of historical studies with reference compounds (amphetamine, chlorpromazine) to determine intercompany reproducibility of results, and (3) an interlaboratory test using reference compounds (MK-801, chlorpromazine) to determine whether partially standardized conditions (animals, sex, doses, vehicles, administration route, observation time points, systemic exposure) might reduce variability of results. RESULTS: Our survey revealed several similarities, e.g., main endpoints of home cage and openfield observations, species, and positive control substances, but also a high level of heterogeneity between different companies with regard to behavioral endpoints during handling and reflex testing, scoring, group size, and timing of studies. Analysis of heterogeneously designed historical studies with amphetamine and chlorpromazine showed the anticipated behavioral changes, albeit with quantitative variability, and identified more robust (e.g., activity, posture, muscle tone, startle reflex, body temperature) and less robust (piloerection, stereotypical behavior, palpebral closure, respiration) Irwin/FOB parameters. A partially standardized interlaboratory test with MK-801 and chlorpromazine showed the expected behavioral changes and principally confirmed the historically-based more/less robust Irwin/FOB parameters, however, it also showed exposure variability and did not show a markedly reduced quantitative variability of behavioral results. DISCUSSION: Our survey and intercompany test results demonstrate certain heterogeneity in design and conduct of Irwin/FOB tests by pharmaceutical companies. Although the general behavioral profiles for the reference compounds were consistently found, quantitative variability of results remained even under partially standardized conditions. This suggests the importance of a high level of standardization with regard to the Irwin/FOB test modification used, scoring system, and observer training, in order to achieve an improved intercompany comparability of Irwin/FOB results.

Do in vitro assays in rat primary neurons predict drug-induced seizure liability in humans?

Drug-induced seizures contribute to the high attrition rate of pharmaceutical compounds in development. The assessment of drug-induced seizure liability generally occurs in later phases of development using low throughput and intensive in vivo assays. In the present study, we evaluated the potential of an in vitro assay for detecting drug-induced seizure risk compared to evaluation in rats in vivo. We investigated the effects of 8 reference drugs with a known seizurogenic risk using micro-electrode array (MEA) recordings from freshly-dissociated rat primary neurons cultured on 48-well dishes for 28 days, compared to their effects on the EEG in anesthetized rats. In addition, we evaluated functional responses and mRNA expression levels of different receptors in vitro to understand the potential mechanisms of drug-induced seizure risk. Combining the functional MEA in vitro data with concomitant gene expression allowed us to identify several potential molecular targets that might explain the drug-induced seizures occurring in both rats and humans. Our data 1) demonstrate the utility of a group of MEA parameters for detecting potential drug-induced seizure risk in vitro; 2) suggest that an in vitro MEA assay with rat primary neurons may have advantages over an in vivo rat model; and 3) identify potential mechanisms for the discordance between rat assays and human seizure risk for certain seizurogenic drugs.

Considerations on nonclinical approaches to modeling risk factors of suicidal ideation and behavior.

Given the serious nature of suicidal ideation and behavior (SIB) and the possibility of treatment-emergent SIB, pharmaceutical companies are now applying more proactive approaches in clinical trials and are considering the value of nonclinical models to predict SIB. The current review summarizes nonclinical approaches to modeling three common risk factors associated with SIB: aggression, impulsivity, and anhedonia. For each risk factor, a general description, advantages and disadvantages, species considerations, nonclinical to clinical translation, and pharmacological validation with respect to treatments associated with SIB are summarized. From this review, several gaps were identified that need to be addressed before use of these nonclinical models can be considered a viable option to predict the relative risk for SIB. Other future directions that may compliment these nonclinical approaches, including the use of selectively-bred or genetically-modified rodent models, transgenic models, gene expression profiling, and biomarker analysis, are discussed. This article was developed with the support of the DruSafe Leadership Group of the International Consortium for Innovation and Quality in Pharmaceutical Development (IQ, www.iqconsortium.org).

On the use of historical control data in pre-clinical safety studies.

A number of methods to formally incorporate historical control information in pre-clinical safety evaluation studies have been proposed in literature. However, it remains unclear when one should use historical data. Focusing on the logistic-normal model, we investigate situations where historical studies may prove to be useful. Aspects of estimation (precision and bias) and testing (power) for treatment effect are investigated under different conditions such as the number of historical control studies, the degree of homogeneity amongst them, the level of treatment effect and different control rates. The possibility to use a selected subset of historical control studies is also explored.

Trait-anxiety and achievement motivation are positively correlated with memory performance in patients who visit a geriatric outpatient clinic with amnestic symptoms.

Memory performance was studied in relation to anxiety and achievement motivation in a sample of 35 patients who were referred to a geriatric outpatient clinic for their complaints of memory dysfunction. State-anxiety appeared not to be associated with memory performance or the severity of dementia. Trait-anxiety and achievement motivation were associated positively with memory performance and negatively with the severity of dementia. The evaluation of anxiety symptoms in the assessment of dementia is recommended.

Evaluation of the bovine corneal opacity-permeability assay as an in vitro alternative to the Draize eye irritation test.

The bovine corneal opacity-permeability assay (BCO-P) was evaluated as an in vitro alternative test model for the Draize eye irritancy test. Fifty pharmaceutical and commercially available compounds were tested in the BCO-P assay. The compounds were selected on the basis of their in vivo irritancy potential as determined in previous Draize tests. Liquids as well as solids were tested. Corneal opacity and permeability were measured to determine ocular irritation potential. When two irritancy classifications (non-irritant and irritant) were considered, 96% of the tested chemicals were classified correctly. A 72% concordance was obtained when four irritancy classifications (non-irritant, mild, moderate and severe irritant) were considered. Furthermore, all compounds that were severe eye irritants in vivo were equally scored in vitro. The results of this study show that the BCO-P assay is a competent in vitro test system for the prediction of ocular irritation of chemicals. This test model can be used as a first screen to avoid in vivo testing of severe ocular irritants.