Safety, Tolerability, and Pharmacokinetics of FAAH Inhibitor BIA 10-2474: A Double-Blind, Randomized, Placebo-Controlled Study in Healthy Volunteers.

This study evaluated the safety, tolerability, pharmacokinetics, and pharmacodynamics of BIA 10-2474, a fatty acid amide hydrolase (FAAH) inhibitor, after first administration to healthy male and female participants. Participants (n = 116) were recruited into this phase I, double-blind, randomized, placebo-controlled, single ascending dose and multiple ascending dose (10-day) study. The primary outcome was the safety and tolerability of BIA 10-2474. Secondary outcomes were pharmacokinetics of BIA 10-2474 and pharmacodynamics, considering plasma concentrations of anandamide and three other fatty acid amides (FAAs) and leukocyte FAAH activity. Single oral doses of 0.25-100 mg and repeated oral doses of 2.5-50 mg were evaluated. BIA 10-2474 was well tolerated up to 100 mg as a single dose and up to 20 mg once daily for 10 days. In the cohort receiving repeated administrations of 50 mg, there were central nervous system adverse events in five of six participants, one with fatal outcome, which led to early termination of the study. BIA 10-2474 showed a linear relationship between dose and area under plasma concentration-time curve (AUC) across the entire dose range and reached steady state within 5-6 days of administration, with an accumulation ratio, based on AUC0-24h , of <2 on Day 10. BIA 10-2474 was rapidly absorbed with a mean terminal elimination half-life of 8-10 hours (Day 10). BIA 10-2474 caused reversible, dose-related increases in plasma FAAs. In conclusion, we propose that these data, as well as the additional data generated since the clinical trial was stopped, do not provide a complete mechanistic explanation for the tragic fatality.

Introduction to the EQIPD quality system.

While high risk of failure is an inherent part of developing innovative therapies, it can be reduced by adherence to evidence-based rigorous research practices. Supported through the European Union's Innovative Medicines Initiative, the EQIPD consortium has developed a novel preclinical research quality system that can be applied in both public and private sectors and is free for anyone to use. The EQIPD Quality System was designed to be suited to boost innovation by ensuring the generation of robust and reliable preclinical data while being lean, effective and not becoming a burden that could negatively impact the freedom to explore scientific questions. EQIPD defines research quality as the extent to which research data are fit for their intended use. Fitness, in this context, is defined by the stakeholders, who are the scientists directly involved in the research, but also their funders, sponsors, publishers, research tool manufacturers, and collaboration partners such as peers in a multi-site research project. The essence of the EQIPD Quality System is the set of 18 core requirements that can be addressed flexibly, according to user-specific needs and following a user-defined trajectory. The EQIPD Quality System proposes guidance on expectations for quality-related measures, defines criteria for adequate processes (i.e. performance standards) and provides examples of how such measures can be developed and implemented. However, it does not prescribe any pre-determined solutions. EQIPD has also developed tools (for optional use) to support users in implementing the system and assessment services for those research units that successfully implement the quality system and seek formal accreditation. Building upon the feedback from users and continuous improvement, a sustainable EQIPD Quality System will ultimately serve the entire community of scientists conducting non-regulated preclinical research, by helping them generate reliable data that are fit for their intended use.

Non-clinical toxicology evaluation of BIA 10-2474.

In 2016, one subject died and four were hospitalized with neurological symptoms during a clinical trial with the fatty acid amide hydrolase (FAAH) inhibitor BIA 10-2474. The present paper reviews the regulatory toxicology studies that were carried out to support the clinical trial application for BIA 10-2474. Animal studies complied with national and international standards including European regulatory guidelines (e.g. EEC Council Directive 75/318/EEC and subsequent amendments). The CNS effects seen in the rat and mouse appear to be common in rodents in such studies and do not in principle seem to be of the type to generate a signal. In the same way in non-human primates, insignificant alterations in the mesencephalon, and especially of the autonomic nervous system (Meissner's plexus in the bowel) in rodents and monkeys were observed in some animals treated with a high dose. Overall, these data, as well as the extensive additional data generated since the accident, support the conclusion that the tragic fatality that occurred during the clinical trial with BIA 10-2474 was unpredictable and that the mechanism responsible remains unknown, from a non-clinical toxicological perspective.

Pharmacology profile of F17464, a dopamine D3 receptor preferential antagonist.

F17464 (N-(3-{4-[4-(8-Oxo-8H-[1,3]-dioxolo-[4,5-g]-chromen-7-yl)-butyl]-piperazin-1-yl}-phenyl)-methanesulfonamide, hydrochloride) is a new potential antipsychotic with a unique profile. The compound exhibits high affinity for the human dopamine receptor subtype 3 (hD3) (Ki = 0.17 nM) and the serotonin receptor subtype 1a (5-HT1a) (Ki = 0.16 nM) and a >50 fold lower affinity for the human dopamine receptor subtype 2 short and long form (hD2s/l) (Ki = 8.9 and 12.1 nM, respectively). [14C]F17464 dynamic studies show a slower dissociation rate from hD3 receptor (t1/2 = 110 min) than from hD2s receptor (t1/2 = 1.4 min) and functional studies demonstrate that F17464 is a D3 receptor antagonist, 5-HT1a receptor partial agonist. In human dopaminergic neurons F17464 blocks ketamine induced morphological changes, an effect D3 receptor mediated. In vivo F17464 target engagement of both D2 and 5-HT1a receptors is demonstrated in displacement studies in the mouse brain. F17464 increases dopamine release in the rat prefrontal cortex and mouse lateral forebrain - dorsal striatum and seems to reduce the effect of MK801 on % c-fos mRNA medium expressing neurons in cortical and subcortical regions. F17464 also rescues valproate induced impairment in a rat social interaction model of autism. All the neurochemistry and behavioural effects of F17464 are observed in the dose range 0.32-2.5 mg/kg i.p. in both rats and mice. The in vitro - in vivo pharmacology profile of F17464 in preclinical models is discussed in support of a therapeutic use of the compound in schizophrenia and autism.

Regulatory safety pharmacology evaluation of BIA 10-2474.

The present paper describes the regulatory safety pharmacology studies that were carried out to support the clinical trial application for BIA 10-2474. Animal studies complied with worldwide regulatory guidelines (e.g. EEC Council Directive 75/318/EEC and subsequent amendments). Oral administration of BIA 10-2474 at doses of 30, 100 and 300 mg/kg to male Han Wistar rats did not cause any significant physiological or behavioral changes, affect the respiration rate or the tidal volume, the gastrointestinal transit, urinary output volume or pH, nor urinary sodium, potassium or chloride excretion. BIA 10-2474, at 30 µg/mL, slightly, but significantly, reduced the hERG outward tail currents by 10.62%, but had no effect at 1, 3 or 10 µg/mL. BIA 10-2474 (1.5, 4.5 and 15 µg/mL) had no substantial effects on resting membrane potential (RMP), maximal upstroke velocity (Vmax), action potential amplitude (APA), action potential duration at 30%, 60% and 90% or action potential triangulation over the 30-min superfusion period in the dog isolated Purkinje fiber. In conscious dogs monitored by telemetry, BIA 10-2474 (20, 50 and 100 mg/kg p.o.) did not significantly modify arterial blood pressure as compared with controls (inter-group comparison), although a tendency toward an increase in arterial blood pressure was observed at 100 mg/kg, with systolic blood pressure being the most affected parameter. In conclusion, BIA 10-2474 had no adverse effects on any of the major vital organ systems, and, unfortunately, the data shed no further light on the mechanism(s) responsible for the clinical trial accident with BIA 10-2474.

Preclinical pharmacological evaluation of the fatty acid amide hydrolase inhibitor BIA 10-2474.

BACKGROUND AND PURPOSE: In 2016, one person died and four others had mild-to-severe neurological symptoms during a phase I trial of the fatty acid amide hydrolase (FAAH) inhibitor BIA 10-2474. EXPERIMENTAL APPROACH: Pharmacodynamic and pharmacokinetic studies were performed with BIA 10-2474, PF-04457845 and JNJ-42165279 using mice, rats and human FAAH expressed in COS cells. Selectivity was evaluated by activity-based protein profiling (APBB) in rats. BIA 10-2474 effect in stroke-prone spontaneously hypertensive rats (SHRSP) was investigated. KEY RESULTS: BIA 10-2474 was 10-fold less potent than PF-04457845 in inhibiting human FAAH in situ but inhibited mouse brain and liver FAAH with ED50 values of 13.5 and 6.2 µg·kg-1 , respectively. Plasma and brain BIA 10-2474 levels were consistent with in situ potency and neither BIA 10-2474 nor its metabolites accumulated following repeat administration. FAAH and α/ß-hydrolase domain containing 6 were the primary targets of BIA 10-2474 and, at higher exposure levels, ABHD11, PNPLA6, PLA2G15, PLA2G6 and androgen-induced protein 1. At 100 mg·kg-1 for 28 days, the level of several lipid species containing arachidonic acid increased. Daily treatment of SHRSP with BIA 10-2474 did not affect mortality rate or increased the incidence of haemorrhage or oedema in surviving animals. CONCLUSIONS AND IMPLICATIONS: BIA 10-2474 potently inhibits FAAH in vivo, similarly to PF-04457845 and interacts with a number of lipid processing enzymes, some previously identified in human cells as off-targets particularly at high levels of exposure. These interactions occurred at doses used in toxicology studies, but the implication of these off-targets in the clinical trial accident remains unclear.

Out of Control? Managing Baseline Variability in Experimental Studies with Control Groups.

Control groups are expected to show what happens in the absence of the intervention of interest (negative control) or the effect of an intervention expected to have an effect (positive control). Although they usually give results we can anticipate, they are an essential component of all experiments, both in vitro and in vivo, and fulfil a number of important roles in any experimental design. Perhaps most importantly they help you understand the influence of variables that you cannot fully eliminate from your experiment and thus include them in your analysis of treatment effects. Because of this it is essential that they are treated as any other experimental group in terms of subjects, randomisation, blinding, etc. It also means that in almost all cases, contemporaneous control groups are required. Historical and baseline control groups serve a slightly different role and cannot fully replace control groups run as an integral part of the experiment. When used correctly, a good control group not only validates your experiment; it provides the basis for evaluating the effect of your treatments.

Inhibition of catechol-O-methyltransferase in the cynomolgus monkey by opicapone after acute and repeated administration.

INTRODUCTION: The aim of the study was to clarify the dose response for inhibition of catechol-O-methyltransferase (COMT) by opicapone, a third generation COMT inhibitor, after acute and repeated administration to the cynomolgus monkey with pharmacokinetic evaluation at the higher dose. METHODS: Three cynomolgus monkeys were used in the study. In the first experiment, COMT inhibition was evaluated over 24 h after the first and at 24 h after the last of 14 daily oral administrations of vehicle, 1, 10 and 100 mg/kg opicapone using a crossover design. In the second experiment, the effect of the maximally effective dose, 100 mg/kg, was retested under the same conditions with additional monitoring of plasma opicapone levels to explore the relationship between pharmacokinetics and pharmacodynamics. RESULTS: Opicapone dose-dependently inhibited COMT activity, significantly so at 10 and 100 mg/kg. Maximal inhibition was 13.1%, 76.4% and 93.2% at 1, 10 and 100 mg/kg respectively, and COMT remained significantly inhibited at 24 h after 10 and 100 mg/kg (42.6% and 60.2% respectively). Following repeated administration of opicapone residual COMT inhibition at 24 h was 15-25% greater at all doses. In contrast to its pharmacodynamic effect, opicapone was rapidly absorbed and eliminated, with no accumulation in plasma following repeated administration. CONCLUSION: Opicapone showed sustained and dose-dependent COMT inhibition despite being rapidly eliminated from plasma and with no evidence for accumulation in plasma after 14 days administration. Opicapone fills the unmet need for a compound with sustained COMT inhibition which will improve levodopa bioavailability in patients with Parkinson's disease.

Evaluating negative-symptom-like behavioural changes in developmental models of schizophrenia.

Many lines of evidence suggest that schizophrenia has a major developmental component and that environmental factors that disrupt key stages of development, such as maternal stress during pregnancy as a result of infection or malnutrition, can increase the risk of developing schizophrenia in later life. This review examines how non-clinical neurodevelopmental models pertinent to schizophrenia have been evaluated for their ability to reproduce behavioural deficits related to the negative symptoms of schizophrenia. The more frequently used are the prenatal application of the mitotoxic agent methylazoxymethanol, prenatal immune challenge and the neonatal ventral hippocampus lesion model. In general they have been extensively evaluated in models considered relevant to positive symptoms of schizophrenia. In contrast, very few studies have examined tests related to negative symptoms and, when they have, it has almost exclusively been a social interaction model. Other aspects related to negative symptoms such as anhedonia, affective flattening and avolition have almost never been studied. Further studies examining other components of negative symptomatology are needed to more clearly associate these deficits with a schizophrenia-like profile as social withdrawal is a hallmark of many disorders. Although there are no truly effective treatments for negative symptoms, better characterisation with a broader range of drugs used in schizophrenia will be necessary to better evaluate the utility of these models. In summary, developmental models of schizophrenia have been extensively studied as models of positive symptoms but, given the unmet need in the clinic, the same effort now needs to be made with regard to negative symptoms.

Rodent models of depression: forced swim and tail suspension behavioral despair tests in rats and mice.

The development of antidepressants requires simple rodent behavioral tests for initial screening before undertaking more complex preclinical tests and clinical evaluation. Presented in the unit are two widely used screening tests used for antidepressants, the forced swim (also termed behavioral despair) test in the rat and mouse, and the tail suspension test in the mouse. These tests have good predictive validity and allow rapid and economical detection of substances with potential antidepressant-like activity. The behavioral despair and the tail suspension tests are based on the same principle: measurement of the duration of immobility when rodents are exposed to an inescapable situation. The majority of clinically used antidepressants decrease the duration of immobility. Antidepressants also increase the latency to immobility, and this additional measure can increase the sensitivity of the behavioral despair test in the mouse for certain classes of antidepressant. Testing of new substances in the behavioral despair and tail suspension tests allows a simple assessment of their potential antidepressant activity by the measurement of their effect on immobility.

Comparison of methods for the assessment of locomotor activity in rodent safety pharmacology studies.

INTRODUCTION: General neurobehavioral assays, like a modified Irwin test or a functional observational battery, are necessary for central nervous system (CNS) safety pharmacology testing near the end of the target validation (early discovery) stage of preclinical drug development. However, at earlier stages, when a greater number of test compounds must be screened for potential CNS side effects, locomotor activity assessment may be a better tool for the comparison of compounds. METHODS: Spontaneous locomotor activity counts obtained from two automated test systems - an infrared beam-based activity meter (Actimeter) and the mechanical vibration-based LABORAS - were compared in rats dosed with chlorpromazine (2-8mg/kg) or caffeine (3-24mg/kg), p.o. A modified Irwin test was also performed to visually observe the neurobehavioral effects. RESULTS: In all three assays, dose-dependent sedation- and excitation-related effects were observed with chlorpromazine and caffeine, respectively. The two automated activity-detection systems exhibited similar sensitivities in determining changes in locomotor activity, but with the LABORAS being more sensitive than the Actimeter in detecting caffeine-induced increases in vertical activity (rearing behavior). DISCUSSION: Infrared beam-based activity detection systems and LABORAS provide relatively-comparable quantitative data regarding locomotor activity. Practical considerations, such as relative cost versus degree of versatility, should be considered when deciding which system to use for the screening of test compounds during the earliest stages of preclinical drug development.

Continuous evaluation of drug withdrawal in the rat using telemetry: effects of morphine and chlordiazepoxide.

INTRODUCTION: The procedures used to assess withdrawal must be sensitive and widely applicable, i.e. not specific to any particular drug class. Furthermore, the measurements should not be affected by repeat testing. METHODS: We have used implanted telemetry devices to continuously follow body temperature, locomotor activity (LMA), heart rate (HR) and mean arterial blood pressure (mean ABP) in addition to food intake and body weight gain over 20days of treatment and 8days of withdrawal. The effects of morphine (32 and 64mg/kg p.o., b.i.d.) and chlordiazepoxide (16, 32 and 64mg/kg p.o., b.i.d.) were studied in rats. RESULTS: The results show that during the treatment phase chronic morphine reduced food intake and body weight gain, increased body temperature, HR, mean ABP and LMA. These effects continued over the 20days of treatment. In contrast, chlordiazepoxide slightly increased food intake and body weight gain throughout the treatment period. It also decreased body temperature and LMA but increased HR and mean ABP after the first few administrations but these effects disappeared over the 20days of treatment. Following discontinuation, both morphine- and chlordiazepoxide-treated rats showed a dose-related decrease in food intake and loss of weight on days 2 and 3 of discontinuation. Morphine discontinuation also induced a nocturnal hypothermia and a diurnal hypertension (i.e. during the light phase) which lasted for 4-5days and also moderate diurnal increases in locomotor activity and heart rate over the first 3days of discontinuation. Chlordiazepoxide discontinuation induced small increases in telemetry parameters some of which, such as the effect on locomotor activity, lasted for more than 5days. The intensity and duration of effects for both substances were broadly dose-related. DISCUSSION: These data show that telemetry can increase the sensitivity of withdrawal experiments to changes that might otherwise be missed and allows a better definition of the time-course of withdrawal effects. This technique is therefore useful as part of safety pharmacology abuse liability evaluation of novel test substances across a broad range of pharmacological and therapeutic classes.

Current approaches and issues in non-clinical evaluation of abuse and dependence.

Preclinical assessment of drug abuse and dependence has been the subject of several recent regulatory guidelines. Both the European and US authorities recommend a tiered approach and are generally aligned on the methods which should be used. The first tier simply compares the pharmacology of the novel substance to known drugs of abuse. The second tier aims to identify abuse and dependence liability more directly. The most direct approach to assessing reinforcing properties is the i.v. self-administration procedure. Unfortunately there is no standardized procedure for evaluating substances with differing potencies, reinforcement properties or pharmacokinetics (PK). Indeed, the choice of training substance, species and procedural parameters can radically affect the outcome. Apart from the lower cost of the rat, the primate presents several advantages for self-administration studies (potentially greater similarity to humans in behavioral effects, active doses and PK). Although it does not measure abuse liability directly, drug discrimination is a powerful method for assessing the similarity of a test substance to a known drug of abuse. In this procedure an animal uses the interoceptive effects of the substance as the discriminative stimulus to determine which of two responses to make. For certain classes of substance, such as hallucinogens acting via the 5-HT(2A) receptor, discrimination is the only procedure currently able to identify them. Drug dependence is assessed by the occurrence of withdrawal effects on drug discontinuation. Although conceptually simple, many factors (duration and frequency of drug treatment, dose/exposure levels, duration of observation after discontinuation) can complicate interpretation. Telemetry may represent a novel approach which allows continuous observation of somatic and behavioral parameters during drug withdrawal thereby increasing sensitivity. Presently available tools can identify essentially all substances known to cause abuse or dependence with little risk of false positives. It remains unclear how effective these models will be with entirely novel substances. Nonetheless, drug abuse/dependence is an area of safety pharmacology where the predictive value of animal models remains very high.

How good are current approaches to nonclinical evaluation of abuse and dependence?

Nonclinical assessment of drug abuse and dependence is the subject of several recent regulatory guidelines, which are generally aligned on the methods to be employed. The most direct approach to assessing reinforcing properties of a drug is the self-administration procedure whereby animals can initiate intravenous injections of the test substance, something they readily do with prototypic drugs of abuse. Complications arise because there is no standardized procedure for evaluating substances with differing potencies, reinforcement properties, or pharmacokinetics. Moreover, the choice of training substance, species, and procedural parameters can radically affect the outcome. Apart from the lower cost of rats, primates present several advantages for self-administration studies with similarity to human pharmacokinetics in particular. The most powerful method for assessing similarities between a test substance and a prototypic drug of abuse is the drug discrimination procedure. In contrast to self-administration, drug discrimination is pharmacologically very specific, often reflecting functional activity at receptor level. Dependence is assessed by the occurrence of withdrawal effects on drug discontinuation. Although conceptually simple, interpretation can be complicated by factors such as duration and frequency of administration and observations as well as the choice of end points. Telemetry allows continuous observation of multiple parameters during withdrawal, thereby increasing sensitivity. Presently available tools identify all substances known to cause abuse or dependence, with little risk of false-positives. It remains unclear, however, how predictive these models are with entirely novel substances. Nonetheless, drug abuse/dependence is an area of safety pharmacology where the predictive value of animal models is remarkably high.

Behavioral indices in antipsychotic drug discovery.

Schizophrenia is characterized by three major symptom classes: positive symptoms, negative symptoms, and cognitive deficits. Classical antipsychotics (phenothiazines, thioxanthenes, and butyrophenones) are effective against positive symptoms but induce major side effects, in particular, extrapyramidal symptoms (EPS). The discovery of clozapine, which does not induce EPS and is thought effective against all three classes of symptom, has driven research for novel antipsychotics with a wider activity spectrum and lower EPS liability. To increase predictiveness, current efforts aim to develop translational models where direct parallels can be drawn between the processes studied in animals and in humans. The present article reviews existing procedures in animals for their ability to predict compound efficacy and EPS liability in relation to their translational validity. Rodent models of positive symptoms include procedures related to dysfunction in central dopamine and glutamatergic (N-methyl-D-aspartate) and serotonin (5-hydroxytryptamine) neurotransmission. Procedures for evaluating negative symptoms include rodent models of anhedonia, affective flattening, and diminished social interaction. Cognitive deficits can be assessed in rodent models of attention (prepulse inhibition) and of learning/memory (object and social recognition, Morris water maze and operant-delayed alternation). The relevance of the conditioned avoidance response is also discussed. A final section reviews procedures for assessing EPS liability, in particular, parkinsonism (catalepsy in rodents), acute dystonia (purposeless chewing in rodents, dystonia in monkeys), akathisia (defecation in rodents), and tardive dyskinesia (long-term antipsychotic treatment in rodents and monkeys). It is concluded that, with notable exceptions (attention, learning/memory, EPS liability), current predictive models for antipsychotics fall short of clear translational validity.

Rodent models of depression: forced swim and tail suspension behavioral despair tests in rats and mice.

The development of antidepressants requires simple rodent behavioral tests for initial screening before undertaking more complex preclinical tests and clinical evaluation. Presented in the unit are two widely used screening tests used for antidepressants, the forced swim (also termed behavioral despair) test in the rat and mouse, and the tail suspension test in the mouse. These tests have good predictive validity and allow rapid and economical detection of substances with potential antidepressant-like activity. The behavioral despair and the tail suspension tests are based on the same principle: measurement of the duration of immobility when rodents are exposed to an inescapable situation. The majority of clinically used antidepressants decrease the duration of immobility. Antidepressants also increase the latency to immobility, and this additional measure can increase the sensitivity of the behavioral despair test in the mouse for certain classes of antidepressant. Testing of new substances in the behavioral despair and tail suspension tests allows a simple assessment of their potential antidepressant activity by the measurement of their effect on immobility.

Use of latency to immobility improves detection of antidepressant-like activity in the behavioral despair test in the mouse.

The behavioral despair test (BDT), also called the forced swim test, is an economic, reliable and sensitive test for the detection of potential antidepressant-like activity of new test substances. The vast majority of clinically active antidepressants are active in the BDT, although substances specifically acting on serotonin transmission are generally reported to be less easily detected. Substances active in the BDT decrease the duration of immobility at doses considered as relatively high. In contrast, some psychostimulants are considered as potential false positives since they are also active in the BDT although they are not recognized as clinically active antidepressants. In the present study we have evaluated the usefulness of latency to the first immobility period as an additional parameter in the BDT to further evaluate the effects of antidepressants and psychostimulants administered intraperitoneally in the mouse. The results show that this measure increases the sensitivity of the test for detecting the effects of tricyclic antidepressants (imipramine, desipramine) and selective serotonin/norepinephrine reuptake inhibitors (duloxetine and venlafaxine) but not of serotonin reuptake inhibitors (fluoxetine and escitalopram). In contrast with previous reports, psychostimulants (amphetamine and modafinil) did not affect the duration or the latency to immobility in the BDT. The mouse strain used in the BDT seems to be an important parameter to discriminate between antidepressants and psychostimulants. These results suggest that the measure of the latency to the first immobility improves the predictive validity of the BDT.

Electroencephalographic and behavioral convulsant effects of hydrobromide and hydrochloride salts of bupropion in conscious rodents.

A novel bromide salt of the antidepressant bupropion (bupropion HBr) has recently been developed and approved for use in the United States. Given previous use of bromides to treat seizures, and that the existing chloride salt of bupropion (HCl) can cause seizures, it is important to determine if the HBr salt may be less likely to cause seizures than the HCl salt. In the present animal studies this was evaluated by means of quantified electroencephalogram (EEG), observation, and the rotarod test in mice and rats. Both bupropion salts were tested at increasing equimolar doses administered intraperitoneally. The results in mice showed that bupropion HCl 125 mg/kg induced a significantly higher ten-fold increase in the mean number of cortical EEG seizures compared to bupropion HBr (7.50 +/- 2.56 vs 0.75 +/- 0.96; p = 0.045), but neither drug caused any brain injuries. In rats bupropion HBr 100 mg/kg induced single EEG seizure activity in the cortical and hippocampal (depth) electrodes and in significantly (p < 0.05) fewer rats (44%) compared to bupropion HCl, which induced 1 to 4 convulsions per rat in all rats (100%) dosed. The total duration of cortical seizures in bupropion HCl-treated rats was significantly longer than the corresponding values obtained in bupropion HBr-treated rats (424.6 seconds vs 124.5 seconds respectively, p < 0.05). Bupropion HCl consistently induced more severe convulsions at each dose level compared to bupropion HBr. Both treatments demonstrated a similar dose-dependent impairment of rotarod performance in mice. In conclusion, these findings suggest that bupropion HBr may have a significantly lower potential to induce seizures in mice and rats, particularly at higher doses, compared to bupropion HCl. Determination of this potential clinical advantage will require human studies. If confirmed by such studies, it is likely that this potential beneficial clinical benefit would be due to the presence of the bromide salt given the long history of the use of bromide to treat seizure disorders.

Preclinical behavioral models for predicting antipsychotic activity.

Schizophrenia is a major psychiatric disease that is characterized by three distinct symptom domains: positive symptoms, negative symptoms, and cognitive impairment. Additionally, treatment with classical antipsychotic medication can be accompanied by important side effects that involve extrapyramidal symptoms (EPS). The discovery of clozapine in the 1970s, which is efficacious in all three symptom domains and has a reduced propensity to induce EPS, has driven research for new antipsychotic agents with a wider spectrum of activity and a lower propensity to induce EPS. The following chapter reviews existing behavioral procedures in animals for their ability to predict compound efficacy against schizophrenia symptoms and liability to induce EPS. Rodent models of positive symptoms include procedures related to hyperfunction in central dopamine and serotonin (5-hydroxytryptamine) systems and hypofunction of central glutamatergic (N-methyl-d-aspartate) neurotransmission. Procedures for evaluating negative symptoms include rodent models of anhedonia, affective flattening, and diminished social interaction. Cognitive deficits can be assessed in rodent models of attention (prepulse inhibition (PPI), latent inhibition) and of learning and memory (passive avoidance, object and social recognition, Morris water maze, and operant-delayed alternation). The relevance of the conditioned avoidance response (CAR) is also discussed. A final section reviews animal procedures for assessing EPS liability, in particular parkinsonism (catalepsy), acute dystonia (purposeless chewing in rodents, dystonia in monkeys), akathisia (defecation in rodents), and tardive dyskinesia (long-term antipsychotic treatment in rodents and monkeys).