Hits and misses with animal models of narcolepsy and the implications for drug discovery.

INTRODUCTION: Narcolepsy is a chronic and rare neurological disorder characterized by disordered sleep. Based on animal models and further research in humans, the dysfunctional orexin system was identified as a contributing factor to the pathophysiology of narcolepsy. Animal models played a larger role in the discovery of some of the pharmacological agents with established benefit/risk profiles. AREAS COVERED: In this review, the authors examine the phenotypes observed in animal models of narcolepsy and the characteristics of clinically used pharmacological agents in these animal models. Additionally, the authors compare the effects of clinically used pharmacological agents on the phenotypes in animal models with those observed in narcolepsy patients. EXPERT OPINION: Research in canine and mouse models have linked narcolepsy to the O×R2mutation and orexin deficiency, leading to new diagnostic criteria and a drug development focus. Advancements in pharmacological therapies have significantly improved narcolepsy management, with insights from both clinical experience and from animal models having led to new treatments such as low sodium oxybate and solriamfetol. However, challenges persist in addressing symptoms beyond excessive daytime sleepiness and cataplexy, highlighting the need for further research, including the development of diurnal animal models to enhance understanding and treatment options for narcolepsy.

Bioequivalence, food effect and comparative pharmacokinetics of SUVN-1105, a novel granule formulation of abiraterone acetate, to Zytiga in healthy male subjects.

PURPOSE: SUVN-1105 is a novel formulation of abiraterone acetate which was developed to demonstrate improved bioavailability, compared to Zytiga and Yonsa, and to reduce the dose and eliminate the food effect. A Phase 1 study was conducted to assess the bioequivalence, food effect, and comparative pharmacokinetics of SUVN-1105 to Zytiga in healthy male subjects. METHODS: The study comprised of 2 segments. Segment 1 was a single-center, 4-period crossover, open-label, fixed treatment sequence, single-dose study to evaluate the safety and pharmacokinetics of SUVN-1105 (N = 12 subjects per period). Segment 2 was a single-center, open-label, single-dose, randomized, 4-period, 4-treatment, 4-sequence crossover study to evaluate bioequivalence and comparative pharmacokinetics of SUVN-1105 against Zytiga (N = 44) under overnight fasted, modified fasted, and fed conditions. RESULTS: Abiraterone exposures appeared to increase proportionately with SUVN-1105 dose (200 mg vs. 250 mg) in Segment 1. In Segment 2, abiraterone exposures of 250 mg SUVN-1105 in the fasted or fed conditions were higher than those of Zytiga 1000 mg in the overnight fasted conditions. Abiraterone exposures of 250 mg SUVN-1105 decreased in the fed conditions (64% and 29% decrease in Cmax and AUC, respectively) compared to overnight fasted conditions. CONCLUSIONS: The abiraterone exposures of 250 mg SUVN-1105 in the fasted or fed conditions fall within the abiraterone exposures of 1000 mg Zytiga in fasted and modified fasted conditions. Single doses of SUVN-1105 were safe and well-tolerated in healthy males both in the fasted and fed conditions.

Progress in Investigational Agents Targeting Serotonin-6 Receptors for the Treatment of Brain Disorders.

Serotonin (5-HT) plays an important role in the regulation of several basic functions of the central and peripheral nervous system. Among the 5-HT receptors, serotonin-6 (5-HT6) receptor has been an area of substantial research. 5-HT6 receptor is a G-protein-coupled receptor mediating its effects through diverse signaling pathways. Exceptional features of the receptors fueling drug discovery efforts include unique localization and specific distribution in the brain regions having a role in learning, memory, mood, and behavior, and the affinity of several clinically used psychotropic agents. Although non-clinical data suggest that both agonist and antagonist may have similar behavioral effects, most of the agents that entered clinical evaluation were antagonists. Schizophrenia was the initial target; more recently, cognitive deficits associated with Alzheimer's disease (AD) or other neurological disorders has been the target for clinically evaluated 5-HT6 receptor antagonists. Several 5-HT6 receptor antagonists (idalopirdine, intepirdine and latrepirdine) showed efficacy in alleviating cognitive deficits associated with AD in the proof-of-concept clinical studies; however, the outcomes of the subsequent phase 3 studies were largely disappointing. The observations from both non-clinical and clinical studies suggest that 5-HT6 receptor antagonists may have a role in the management of neuropsychiatric symptoms in dementia. Masupirdine, a selective 5-HT6 receptor antagonist, reduced agitation/aggression-like behaviors in animal models, and a post hoc analysis of a phase 2 trial suggested potential beneficial effects on agitation/aggression and psychosis in AD. This agent will be assessed in additional trials, and the outcome of the trials will inform the use of 5-HT6 receptor antagonists in the treatment of agitation in dementia of the Alzheimer's type.

Potential beneficial effects of masupirdine (SUVN-502) on agitation/aggression and psychosis in patients with moderate Alzheimer's disease: Exploratory post hoc analyses.

OBJECTIVES: The effects of masupirdine on the neuropsychiatric symptoms were explored. METHODS: Masupirdine (SUVN-502) was evaluated for its effects on cognition in patients with moderate AD. The prespecified primary outcome showed no drug-placebo difference. Post hoc analyses of domains of the 12-item neuropsychiatric inventory scale were carried out. RESULTS: In a subgroup of patients (placebo, n = 57; masupirdine 50 mg, n = 53; masupirdine 100 mg, n = 48) with baseline agitation/aggression symptoms ≥1, a statistically significant reduction in agitation/aggression scores was observed in masupirdine 50 mg (95% confidence interval (CI), -1.9 to -0.5, p < 0.001) and masupirdine 100 mg (95% CI, -1.7 to -0.3, p = 0.007) treated arms at Week 13 in comparison to placebo and the effect was sustained for trial duration of 26 weeks in the masupirdine 50 mg treatment arm (95% CI, -2.3 to -0.8, p < 0.001). Similar observations were noted in the subgroup of patients (placebo, n = 29; masupirdine 50 mg, n = 30; masupirdine 100 mg, n = 21) with baseline agitation/aggression symptoms ≥3. In the subgroup of patients (placebo, n = 28; masupirdine 50 mg, n = 28; masupirdine 100 mg, n = 28) who had baseline psychosis symptoms and/or symptom emergence, a significant reduction in psychosis scores was observed in the masupirdine 50 mg (Week 4: 95% CI, -2.8 to -1.4, p < 0.001; Week 13: 95% CI, -3.3 to -1.3, p < 0.001) and masupirdine 100 mg (Week 4: 95% CI, -1.4 to 0, p = 0.046; Week 13: 95% CI, -1.9 to 0.1, p = 0.073) treatment arms in comparison to placebo. CONCLUSION: Further research is warranted to explore the potential beneficial effects of masupirdine on NPS.

Safety, Tolerability, and Pharmacokinetics of Ropanicant (SUVN-911), a Novel Alpha4 Beta2 Nicotinic Acetylcholine Receptor (α4ß2 nAChR) Antagonist, in Healthy Adult and Elderly Subjects.

BACKGROUND AND OBJECTIVES: Ropanicant hydrochloride (previously known as SUVN-911, hereinafter referred to as ropanicant) is a novel alpha4 beta2 nicotinic acetylcholine receptor (α4ß2 nAchR) antagonist being developed for the treatment of major depressive disorder. The objectives of the present studies were to evaluate the safety, tolerability, and pharmacokinetics of ropanicant after single and multiple ascending doses and to evaluate the effect of food, sex, and age on its pharmacokinetics in healthy subjects. METHODS: Two phase I studies have been conducted for ropanicant. Study 1 is a randomized, double-blind, placebo-controlled, first-in-human study to evaluate the safety, tolerability, and pharmacokinetics of single ascending doses (0.5, 6, 15, 30, and 60 mg) and multiple ascending doses (15, 30, and 45 mg) of ropanicant administered orally for 14 days to healthy male subjects. In Study 2, the effect of food, sex, and age on ropanicant pharmacokinetics was evaluated following a single 30-mg oral dose. RESULTS: Ropanicant at single doses up to 60 mg and multiple doses up to 45 mg once daily was found to be safe and well tolerated in healthy subjects. The most frequently reported adverse events were headache and nausea. Ropanicant exposures were more than dose proportional following single and multiple administrations. Urinary excretion of unchanged ropanicant was low across the doses. Upon multiple dosing, 1.5- to 2.5-fold higher exposures for maximum concentration and 1.6- to 4.0-fold higher exposures for area under the concentration-time curve from time 0-24 h were observed on day 14 as compared with day 1. Sex had an effect on the pharmacokinetics of ropanicant as a 64% higher area under the concentration-time curve from time 0 to 24 h and a 26% higher maximum concentration was observed in female adults when compared with male adults. Plasma exposures were comparable in fasted versus fed conditions and in adult versus elderly subjects. CONCLUSIONS: Ropanicant was found to be safe and well tolerated following single and multiple oral administrations in healthy subjects. Ropanicant showed nonlinear pharmacokinetics and accumulation following multiple dosing. Urinary excretion represents an insignificant elimination pathway for ropanicant. Ropanicant pharmacokinetics were sex dependent, and food and age had no effect on its pharmacokinetics. CLINICAL TRIAL REGISTRATION: NCT03155503 and NCT03551288.

Effect of Concurrent Use of Memantine on the Efficacy of Masupirdine (SUVN-502): A Post Hoc Analysis of a Phase 2 Randomized Placebo-Controlled Study.

INTRODUCTION: Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive deterioration in cognition, memory and activities of daily living. Selective blockade of serotonin-6 (5-HT6) receptors, which are exclusively localized to the central nervous system, is reported to play an important role in learning and memory. Masupirdine is a potent and selective 5-HT6 receptor antagonist with pro-cognitive properties in animal models of cognition. METHODS: The efficacy and safety of masupirdine were evaluated in patients with moderate AD concurrently treated with donepezil and memantine. A total of 564 patients were randomized in a 1:1:1 ratio. The study consisted of a 26-week double-blind treatment period. The primary efficacy outcome was the 11-item cognitive subscale of the Alzheimer's Disease Assessment Scale (ADAS-Cog 11). Changes from baseline were analyzed using a mixed effects model for repeated measures (MMRM). In exploratory post hoc analyses, patients were subdivided based on the use of memantine dosage forms and memantine plasma concentrations, to evaluate the impact of memantine on the efficacy of masupirdine. RESULTS: In an exploratory post hoc analysis, less worsening in cognition (ADAS-Cog 11 scores) was observed with masupirdine treatment as compared with placebo in patients whose trough memantine plasma concentrations were ≤ 100 ng/mL. CONCLUSIONS: Although prespecified study endpoints of the phase 2 study were not met, these exploratory post hoc subgroup observations are hypothesis-generating and suggest that the efficacy of masupirdine was adversely affected by concurrent therapy with memantine. Further assessment of masupirdine to determine its potential role as a treatment option for cognitive deficits associated with AD is warranted. TRIAL REGISTRATION: The study was registered at ClinicalTrials.gov (NCT02580305).

Effect of masupirdine (SUVN-502) on cognition in patients with moderate Alzheimer's disease: A randomized, double-blind, phase 2, proof-of-concept study.

Introduction: This study explored the efficacy and safety of a serotonin-6 receptor antagonist, masupirdine, as adjunct treatment in patients with moderate Alzheimer's disease (AD) concomitantly treated with donepezil and memantine. Methods: The effects of masupirdine were evaluated in patients with moderate AD dementia on background treatment with donepezil and memantine. Five hundred thirty-seven patients were expected to be randomized in a 1:1:1 ratio, using permuted blocked randomization. After a 2- to 4-week screening period, the study consisted of a 26-week double-blind treatment period, and a 4-week washout period. The primary efficacy measure was the 11-item cognitive subscale of the Alzheimer's Disease Assessment Scale (ADAS-Cog 11). Secondary efficacy measures were Clinical Dementia Rating Scale-Sum of Boxes, Mini-Mental State Examination, 23-item Alzheimer's Disease Co-operative Study Activities of Daily Living, and 12-item Neuropsychiatric Inventory. Changes from baseline were analyzed using a mixed effects model for repeated measures (MMRM). A total of 564 patients were randomized to receive either daily masupirdine 50 mg (190 patients), masupirdine 100 mg (185 patients), or placebo (189 patients). The study is registered at ClinicalTrials.gov (NCT02580305). Results: The MMRM results showed statistically non-significant treatment differences in change from baseline in ADAS-Cog 11 scores at week 26, comparing each masupirdine dose arm to the placebo arm. No significant treatment effects were observed in the secondary evaluations. Discussion: Masupirdine was generally safe and well tolerated. Possible reasons for the observed trial results are discussed. Highlights: Masupirdine was evaluated in moderate Alzheimer's disease patients.First trial in class with background treatment of donepezil and memantine.Masupirdine was generally safe and well tolerated.Possible reasons for the observed trial results are discussed.

Ropanicant (SUVN-911), an α4ß2 nicotinic acetylcholine receptor antagonist intended for the treatment of depressive disorders: pharmacological, behavioral, and neurochemical characterization.

RATIONALE: Ropanicant (SUVN-911) (3-(6-Chloropyridine-3-yloxymethyl)-2-azabicyclo (3.1.0) hexane hydrochloride) is a novel α4ß2 nicotinic acetylcholine receptor (nAChR) antagonist being developed for the treatment of depressive disorders. OBJECTIVES: Pharmacological and neurochemical characterization of Ropanicant to support a potential molecule for the treatment of depressive disorders. METHODS: Ropanicant was assessed for antidepressant-like activity using the rat forced swimming test (FST) and differential reinforcement of low rate -72 s (DRL-72 s). Alleviation of anhedonia was assessed in chronic mild stress model using sucrose preference test. To understand the mechanism of action, serotonin levels, ionized calcium-binding adaptor molecule 1 (Iba1), and brain-derived neurotrophic factor (BDNF) were determined. The onset of antidepressant-like activity was determined using the reduction in submissive behavior assay. The effects on cognition and sexual functions were assessed using the object recognition task and sexual dysfunction assay respectively. Interaction of Ropanicant, TC-5214, and methyllycaconitine (MLA) with citalopram was investigated individually in mice FST. RESULTS: Ropanicant exhibited antidepressant like properties in the FST and DRL-72 s. A significant reduction in anhedonia was observed in the sucrose preference test. Oral administration of Ropanicant produced a significant increase in serotonin and BDNF levels, with a reduction in the Iba1 activity. The onset of antidepressant like effect with Ropanicant was within a week of treatment, and was devoid of cognitive dulling and sexual dysfunction. While Ropanicant potentiated the effect of citalopram in FST, such an effect was not observed with MLA or TC-5214. CONCLUSIONS: Preclinical studies with Ropanicant support the likelihood of its therapeutic utility in the treatment of depressive disorders.

Short-term toxicity study of 1-aminobenzotraizole, a CYP inhibitor, in Wistar rats.

1-Aminobenzotriazole (ABT) is a pan-specific, mechanism-based inhibitor of CYP P450 enzymes, often used as co-treatment to investigate the metabolism-dependent toxicity of drugs or chemicals. To assess the confounding effects of ABT in such kind of mechanistic studies, a repeated dose toxicity study with ABT following 7 days oral administration at 0, 25, 50 and 100 mg/kg/day was performed in Wistar rats (5 rats/sex/group). Wistar rat is selected as a model being one of the well characterized rodent species, widely used for toxicity and toxicokinetics studies. The standard parameters of general toxicity study viz. clinical signs, body weight, feed consumption, clinical, gross and histopathology were evaluated. The ABT was tolerated up to the highest tested dose of 100 mg/kg/day. No clinical signs, mortality or effect on feed consumption at any dose. Slight increase in body weight gain was noted in ABT treated females. Increased reticulocyte, and decreased triglycerides, BUN, A/G ratio and plasma potassium; increased weight of liver, kidneys, adrenals and thyroid was noted in ABT treated animals. Microscopically, hypertrophic findings were noted in liver, thyroid, adrenal glands, pituitary and uterus. Some of these changes were observed at as low as 25 mg/kg/day, therefore, NOEL could not be established. Based on this study, it is concluded that ABT is tolerable up to 100 mg/kg/day with some variations in clinical pathology, organ weight and histopathology; these changes should be considered during the assessment of any mechanistic study with ABT. Findings of this manuscript were presented at 58th meeting of the Society of Toxicology, Baltimore, 11 March 2019.

Discovery and Preclinical Characterization of Usmarapride (SUVN-D4010): A Potent, Selective 5-HT4 Receptor Partial Agonist for the Treatment of Cognitive Deficits Associated with Alzheimer's Disease.

A series of oxadiazole derivatives were synthesized and evaluated as 5-hydroxytryptamine-4 receptor (5-HT4R) partial agonists for the treatment of cognitive deficits associated with Alzheimer's disease. Starting from a reported 5-HT4R antagonist, a systematic structure-activity relationship was conducted, which led to the discovery of potent and selective 5-HT4R partial agonist 1-isopropyl-3-{5-[1-(3-methoxypropyl) piperidin-4-yl]-[1,3,4]oxadiazol-2-yl}-1H-indazole oxalate (Usmarapride, 12l). It showed balanced physicochemical-pharmacokinetic properties with robust nonclinical efficacy in cognition models. It also showed disease-modifying potential, as it increased neuroprotective soluble amyloid precursor protein alpha levels, and dose-dependent target engagement and correlation of efficacy with oral exposures. Phase 1 clinical studies have been completed and projected efficacious concentration was achieved without any major safety concerns. Phase 2 enabling long-term safety studies have been completed with no concerns for further development.

First-in-Human Studies to Evaluate the Safety, Tolerability, and Pharmacokinetics of a Novel 5-HT4 Partial Agonist, SUVN-D4010, in Healthy Adult and Elderly Subjects.

BACKGROUND AND OBJECTIVE: SUVN-D4010 is a novel, potent, highly selective 5-HT4 partial agonist intended for the treatment of cognitive disorders. The objective of the clinical study was to characterize the safety, tolerability, and pharmacokinetics of SUVN-D4010 in healthy adults after single and multiple doses, and to evaluate the effect of food, sex, and age on the pharmacokinetics. METHODS: Single-ascending dose and multiple-ascending dose studies for 14 days were conducted in healthy adults using a randomized, double-blind design. The effects of food, sex, and age on SUVN-D4010 pharmacokinetics (25 mg single dose) were evaluated using an open-label, two-period, randomized, fed and fasted, crossover design. Pharmacokinetics and safety assessments were conducted throughout the study. RESULTS: SUVN-D4010 at a single dose up to 45 mg and multiple doses up to 40 mg once daily was found to be safe and well tolerated in healthy adults. The most frequently reported adverse events were headache and nausea. SUVN-D4010 exposure was dose proportional across the tested doses. Steady state was achieved on day 2 after once-daily dosing for 14 days. Food had no significant effect on the exposures but an increase in median time to attain the maximum plasma concentration (tmax) from 2 h in a fasted state to 3.5 h in fed state was observed. The maximum plasma concentration (Cmax) and the area under the concentration-time curve (AUC) of SUVN-D4010 was 37% and 39%, respectively, lower in adult females compared to males following administration of a single 25 mg dose. In the elderly population, Cmax and AUC of SUVN-D4010 were 42% and 37%, respectively, lower compared to adult males following administration of a single 25 mg dose. SUVN-D4010 was well tolerated and safe in elderly subjects (≥ 65 years) following a single 25 mg dose. CONCLUSION: SUVN-D4010 was found to be safe and well tolerated in healthy human subjects. SUVN-D4010 followed linear pharmacokinetics across the dose range. Accumulation was in the range of 1.3- to 1.4-fold after multiple dosing. Renal excretion is not the major route of elimination. Food had no effect on the exposures but increased the tmax of SUVN-D4010. Exposures were lower in females and elderly subjects suggesting sex and age effects on the pharmacokinetics of SUVN-D4010 and possible dose adjustment in these populations. SUVN-D4010 was well tolerated and safe in elderly subjects after a single dose. Clinical trial identifiers: NCT02575482 and NCT03031574.

Safety, Tolerability, and Pharmacokinetics of SUVN-G3031, a Novel Histamine-3 Receptor Inverse Agonist for the Treatment of Narcolepsy, in Healthy Human Subjects Following Single and Multiple Oral Doses.

BACKGROUND AND OBJECTIVE: SUVN-G3031 is a novel, potent, and selective histamine-3 receptor (H3R) inverse agonist in development for the treatment of narcolepsy. Our objective was to characterize the safety, tolerability, and pharmacokinetics of SUVN-G3031 in healthy young adults after single and multiple doses, and to evaluate the effect of food, gender, and age on the pharmacokinetics. METHODS: A single ascending dose (SAD) and a multiple ascending dose (MAD) study for 14 days was conducted in healthy young adults using a randomized, double-blind study design. The effect of food, gender, and age on SUVN-G3031 pharmacokinetics (6 mg as a single dose) was evaluated using an open-label, two-period, randomized, crossover design in fed and fasted states. Pharmacokinetics and safety assessments were conducted throughout the study. RESULTS: Single doses of SUVN-G3031 up to 20 mg and multiple doses up to 6 mg once daily were found to be safe and well tolerated in healthy young adults. The most frequently reported adverse events were abnormal dreams, dyssomnia, and hot flushes. SUVN-G3031 exposure was dose proportional across the tested doses. Steady state was achieved on day 6 after once-daily dosing. Renal excretion (~ 60%) of unchanged SUVN-G3031 was the major route of elimination. Food, gender, and age did not have any clinically meaningful effect on SUVN-G3031 exposure. CONCLUSION: SUVN-G3031 was found to be safe and well tolerated in healthy human subjects without any effect of age, gender, and food on the pharmacokinetics and safety profile. Clinical Trials Registration (https://clinicaltrials.gov): NCT04072380 and NCT02342041.

Safety, Tolerability and Pharmacokinetics of the Serotonin 5-HT6 Receptor Antagonist, SUVN-502, in Healthy Young Adults and Elderly Subjects.

BACKGROUND AND OBJECTIVE: SUVN-502, a selective 5-HT6 receptor antagonist, was found to be active in preclinical models of cognitive deterioration suggesting a potential role in the treatment of dementia related to Alzheimer's disease. The objective of this study was to characterize the safety, tolerability and pharmacokinetics of SUVN-502 in healthy young adults and elderly subjects following single and multiple oral doses. METHODS: Single doses (5, 15, 50, 100 and 200 mg SUVN-502) and multiple doses (50, 100 and 130 mg SUVN-502 once daily for 7 days) were evaluated in healthy young adults and multiple doses (50 and 100 mg SUVN-502 once daily for 14 days) were evaluated in elderly subjects using randomized, double-blind, placebo-controlled, dose-escalating study designs. The effect of food, gender and age on SUVN-502 pharmacokinetics (100 mg single dose) was evaluated using an open-label, two-period, randomized, fed and fasted in a crossover design. SUVN-502 and M1 (major metabolite of SUVN-502) were monitored using validated analytical methods. RESULTS: SUVN-502 is safe and well tolerated up to the highest tested single dose of 200 mg in healthy young adults and multiple doses up to 130 mg for 7 days and 100 mg for 14 days in healthy young adults and elderly subjects, respectively. Exposures of SUVN-502 and M1 were more than dose-proportional over the evaluated dose range. Food and gender did not have a clinically meaningful effect on SUVN-502 exposure. The mean SUVN-502 total (AUC0-∞, and AUC0-last) and peak exposures (Cmax) were 2.9- and 2.2-fold higher, respectively, in elderly subjects compared to young subjects. Steady-state was achieved for SUVN-502 and M1 within 7 days after once-daily dosing of SUVN-502. CONCLUSIONS: SUVN-502 exhibited an acceptable safety, tolerability and pharmacokinetic profile in healthy young adults and elderly subjects. Based on the above results, 50 and 100 mg once-daily doses of SUVN-502 were advanced to Phase 2 evaluation in patients with moderate AD.

Assessment of toxicity and tolerability of a combination vehicle; 5% Pharmasolve, 45% Propylene glycol and 50% Polyethylene glycol 400 in rats following repeated intravenous administration.

The selection of a suitable vehicle for administration of NCEs in non-clinical studies is always a challenge for poorly soluble compounds. Challenge is increased if the dose formulation is intended for intravenous (i.v.) administration where isotonic, biologically compatible pH and solution form is an absolute requirement. Vehicle toxicity and tolerability data are not readily available for a number of combination vehicles therefore, an i.v. tolerability studies was planned in rats with 5% v/v Pharmasolve (NMP), 45% v/v Propylene glycol (PG) and 50% v/v Polyethylene glycol (PEG) 400 combination, at dose volume of 0.5, 1, 2 and 5 mL/kg body weight for 28 days. The vehicle combination was administered via lateral tail vein and effects on clinical signs, body weights, feed consumption, clinical pathology and histopathology were evaluated. Clinical signs of toxicity like tremors, convulsions and death were noticed at 5 mL/kg during the course of the study. At 2 mL/kg, injection site injury without systemic toxicity was noticed. In conclusion, 1 mL/kg of a combination vehicle of 5% NMP, 45% PG and 55% PEG 400 can be administered intravenously once-a-day up to 28 days without any discomfort or injury to rats.

Evaluation of clinical chemistry analytes from a single mouse using diluted plasma: effective way to reduce the number of animals in toxicity studies.

Clinical chemistry is an essential analytical tool in many areas of research, drug assessment and development, and in the evaluation of general health. A certain amount of blood is required to evaluate all blood analytes. Experiments where mice are used, it is difficult to measure all analytes due to the small amount of blood that can be obtained from a single animal. To overcome this problem, separate cohorts of animals are used in toxicity studies for hematology and biochemistry analysis. This requires the use of extra animals and additional resources. Hence interpretation of results derived from using these different animals can be unreliable. This study was undertaken to explore the possibility of using diluted plasma for measuring various biochemistry analytes. Plasma from mice was diluted to 3, 5 and 10-fold with Water for Injection, and various biochemistry analytes were analyzed using an automated analyzer. Results of diluted and undiluted plasma from the same mouse were compared. Most of the analytes from the diluted plasma were found to be well within the ranges of the undiluted plasma except for sodium, potassium and chloride. Diluting plasma to analyze some analytes also freed up undiluted plasma for analyzing electrolytes. In conclusion, in order to obtain reliable and interpretable data from a single mouse it is worthwhile considering diluting the plasma, which should reduce the number of animals used in an experiment.

Synthesis and SAR of Imidazo[1,5-a]pyridine derivatives as 5-HT4 receptor partial agonists for the treatment of cognitive disorders associated with Alzheimer's disease.

Alzheimer's disease (AD) is a neurodegenerative disease which has a higher prevalence and incidence in older people. The need for improved AD therapies is unmet. The 5-hydroxytryptamine4 receptor (5-HT4R) partial agonists may be of benefit for both the symptomatic and disease-modifying treatment of cognitive disorders associated with AD. Herein, we report the design, synthesis and SAR of imidazo[1,5-a] pyridine derivatives as 5-HT4R partial agonists. The focused SAR, optimization of ADME properties resulted the discovery of compound 5a as potent, selective, brain penetrant 5-HT4 partial agonist as a lead compound with good ADME properties and efficacy in both symptomatic and disease modifying animal models of cognition.

Determining the effect of storage conditions on prothrombin time, activated partial thromboplastin time and fibrinogen concentration in rat plasma samples.

Coagulation parameters are usually included in clinical and preclinical safety studies to evaluate the effect of xenobiotics on the extrinsic or intrinsic pathways of coagulation. The analysis is generally performed at the time of terminal sacrifice where many activities are scheduled. Chances of delay in analysis are likely particularly when blood is collected for coagulation via the abdominal vena cava. This experiment was planned to assess the variations in coagulation parameters caused by delay in analysis as well as by storage conditions. Blood was collected from the posterior vena cava under isoflurane anesthesia, and the plasma was separated immediately. Coagulation parameters were evaluated at 0, 6, 24 and 48 h from the plasma stored at room temperature, as well as plasma stored under refrigerated and freezing conditions. Stability of the analytes in blood was also evaluated under refrigerated conditions for 6 h. All parameters were analyzed using a semi-automated coagulometer. Prothrombin time (PT) was stable under all three storage conditions for up to 6 h. Although statistically significant differences were observed for activated partial thromboplastin time (APTT) at room and refrigeration temperatures for up to 6 h, the difference was clinically non-relevant. Fibrinogen was found to be the most stable parameter that showed consistency in results even up to 48 h under all three storage conditions. Plasma for PT can be stored and analyzed without any significant changes for up to 6 h from the actual blood collection, while fibrinogen level testing can be extended for up to 48 h after collection under any storage condition. For reliable APTT results, plasma samples should be run immediately after collection.

Mutagenicity and clastogenicity evaluation of metaphenoxy benzyl chloride by ames and micronucleus assays.

Metaphenoxy Benzyl Chloride (3-PBC; CAS # 53874-66-1) is a commonly used intermediate in organic synthesis and is a widely used chemical building block. There is likelihood of human contact with 3-PBC in the process of organic or pesticide synthesis and even through as impurity in the product. Further, this chemical has been reported to be found in water reservoirs causing a threat to aqueous flaura and fauna. Genotoxic alert has been suspected for the chemical 3-PBC based on its structure hence, the impetus of present work was to assess the mutagenic potential of 3-PBC using Ames bacterial reverse-mutation assay and in vitro micronucleus assay. 3-PBC was tested for mutagenic potential at six different concentrations, with 0.05 (without metabolic activation) and 0.50 (with metabolic activation) µL/plate as the highest concentrations, followed by five lower concentrations with 2-fold spacing. In clastogenic evaluation, 3-PBC was tested at concentrations ranged from 0.31 to 4.88 µL/mL to assess micronucleus induction in mammalian cells viz. Chinese Hamster Ovarian-K1 cells (CHO-K1 cells). In the Ames assay, 3-PBC did not show mutagenicity in all five tester strains of Salmonella typhimurium viz. TA98, TA100, TA102, TA1535 and TA1537 both in the presence and absence of a metabolic activation system and found to be nonclastogenic when evaluated in "CHO-K1 cells".

Mutagenicity and clastogenicity evaluation of tacrine by Ames and micronucleus assays.

Tacrine was evaluated for its mutagenic and clastogenic activities using the Ames bacterial reverse-mutation assay and the rodent bone marrow micronucleus assay. Tacrine was tested for mutagenic potential at six different concentrations, with 1,250 µg/plate as the highest concentration, followed by five lower concentrations with 2-fold spacing. In clastogenic evaluation, tacrine was administered orally to Wistar rats for 2 days at 5, 10, and 20 mg/kg body weights to assess micronucleus induction in bone marrow erythrocytes. In the Ames assay, tacrine showed nonmutagenicity in four tester strains of Salmonella typhimurium viz. TA98, TA100, TA102, and TA1535, but it was found to be mutagenic in the TA1537 tester strain, both in the presence and absence of a metabolic activation system. Tacrine was found to be nonclastogenic on bone marrow cells of rats at all doses tested and was found to be mutagenic in only the TA1537 strain of Salmonella.