Respiratory Safety Pharmacology Research Articles

SDH, a novel diarylheptane compound, is a potential treatment for inflammatory bowel disease by restoring epithelial barrier function

BackgroundThe global prevalence of inflammatory bowel disease (IBD) is increasing, and mucosal healing is the preferred treatment target of IBD. Sodium (aS,9 R)− 3-hydroxy-16,17-dimethoxy-15-oxidotricyclo[12.3.1.12,6]nonadeca-1(18),2,4,6(19),14,16-hexene-9-yl sulfate hydrate (SDH) is a novel diarylheptane compound, which is designed to treat IBD. Hence, we investigated the potent therapeutic activity of SDH against IBD and explored the underlying mechanisms, and determined if SDH is a safe and well-tolerated oral therapeutic for IBD treatment. MethodsWe characterized its therapeutic properties in vitro and in vivo using Caco-2 cell monolayer and dextran sodium sulfate (DSS)- or 2,4,6-trinitro-benzene sulfonic acid (TNBS)-induced colitis models. We conducted nonclinical toxicology and safety pharmacology research, including general toxicity, toxicokinetics, pharmacokinetics, metabolism and plasma protein binding, cardiovascular safety pharmacology, central nervous system safety pharmacology, respiratory safety pharmacology, fertility and early embryonic development toxicity, reverse mutation assay, chromosomal aberration assay and micronucleus test. ResultsThe results showed that SDH promoted expression of tight junction proteins, and protected the integrity and permeability of the epithelial barrier in both cell and animal models. Moreover, lower doses of SDH showed the similar or better efficacy than cyclosporine A (CsA) and mesalazine in DSS- or TNBS-induced colitis animals. Furthermore, our results identified that SDH has satisfactory safety in these studies we tested. In summary, SDH restored the epithelial barrier through tight junction proteins and was expected to be a novel therapeutic agent for the treatment of IBD.

Translatability of the S7A core battery respiratory safety pharmacology studies: Preclinical respiratory and related clinical adverse events

IntroductionBefore entering into first-in-human studies, most new chemical entities must undergo a series of preclinical evaluations. ICH S7A safety pharmacology (SP) guidelines, adopted in 2001, include respiratory assessments as part of the core battery. Despite these safety measures being in place for nearly two decades, studies examining the relationship between preclinical findings captured in respiratory SP studies and clinical respiratory adverse events (AEs) are sparse. Therefore, the aim of this study is to evaluate the predictive value of preclinical respiratory observations to identify clinical respiratory AEs for both investigational products in early drug development and approved drugs. MethodThree independent databases were interrogated to evaluate the concordance between preclinical and clinical respiratory AEs. Two databases stem from early clinical phase studies, evaluating 52 and 128 investigational products respectively. The third database was derived from a large repository of nearly 4000 FDA and EMA drug approval documents. ResultsAnalysis of early phase clinical studies revealed little to no predictive risk for clinical respiratory adverse events when respiratory findings were observed in preclinical studies, with a positive predictive value (PPV) of 27% and 36% for each dataset respectively. In addition, the likelihood ratio, which reflects the shift in predictability of human risk, was 1.02 and 0.76 respectively, indicating no change in liability. Evaluation of approved drugs revealed a small shift in predictability for preclinical respiratory findings to translate into respiratory clinical AE, with likelihood ratios ranging from 2.5–3.4 and PPV of 18–29% for severe AEs such as lung disorder, respiratory depression and respiratory failure. DiscussionAltogether the translatability of preclinical respiratory findings into clinical AEs is low. Mandating dedicated respiratory SP studies as part of the core battery should be reconsidered in light of the low translatability of respiratory risk clinically and can be effectively incorporated into toxicology investigations.

Safety Pharmacology Study Results and their Impact on the Design of First-in-human Trials for Authorised Oncology Therapies

Safety pharmacology studies are conducted to elucidate possible safety risks on cardiovascular (CV), central nervous system (CNS) and respiratory systems, and are usually carried out prior to first-in-human (FIH) trials. These tests are either standalone tests, or have relevant endpoints integrated in repeat-dose toxicology studies. To review safety pharmacology study results for authorised oncology therapies and to assess how these results have impacted the design of FIH trials of these agents. Bearing in mind the 3Rs principle for animal use (reduction, refinement and replacement), the design of safety pharmacology studies and their outcome for 30 new anticancer medicinal products (both small molecules and biotechnology-derived products) authorised by the European Medicines Agency (EMA) between 2011 and 2015 was reviewed. The impact of the safety pharmacology study results on the design of the FIH trials was also investigated. Our analysis shows that all CNS and respiratory safety pharmacology tests were negative, while for the CV system, 61% of small molecules had positive effects in vitro and/or in vivo and only one out of seven biotechnology-derived products had positive effects in vivo. Regarding the impact of safety pharmacology on clinical trial study design, CV safety pharmacology results for small molecules influenced FIH trial designs in 60% of cases. Based on this subset of data in the oncology therapeutic area, results indicate that the use of safety pharmacology endpoints in repeat-dose toxicology tests could be further utilised as compared with stand-alone safety pharmacology studies, in particular for the CNS and respiratory systems.

Nonclinical safety assessment of SPX-101, a novel peptide promoter of epithelial sodium channel internalization for the treatment of cystic fibrosis

Background: ENaC inhibition has long been an attractive therapeutic target for the treatment of cystic fibrosis. However, previous attempts at developing ENaC inhibitors have been unsuccessful due to complications arising from systemic circulation of the compounds. Here, we describe the preclinical toxicology assessment of a new inhaled peptide promoter of ENaC internalization delivered as a nebulized aerosol.Methods: Preclinical assessment of SPX-101 safety was determined using an in vitro hERG assay, bolus injection of SPX-101 in a canine cardiovascular and respiratory safety pharmacology model and 28-day inhalation toxicology studies of nebulized drug in rats and dogs.Results: SPX101 had no effects on the respiratory, cardiac or central nervous systems. The 28-day inhalation toxicology studies of nebulized SPX-101 in rats and dogs revealed no drug-related adverse events. Plasma levels of SPX-101 peaked less than 1 h after the end of treatment in rats and were below the limit of detection in canine models.Conclusions: SPX-101, a novel peptide promoter of ENaC internalization, elicited no adverse effects at doses up to the MFD and in excess of the highest preclinical efficacious and expected clinical doses. In contrast to channel blockers like amiloride and derivative small molecules, SPX-101 does not achieve significant systemic circulation, thus doses are not limited due to toxic side effects like hyperkalemia and weight loss.

Inclusion of neurobehavioural and respiratory safety pharmacology endpoints in the 4-week rat general toxicology studies

Inclusion of neurobehavioural and respiratory safety pharmacology endpoints in the 4-week rat general toxicology studies

Apneic events – A proposed new target for respiratory safety pharmacology

Current practice in respiratory safety pharmacology generally follows the regulatory guidance provided by the ICH document S7A and focuses on measures of pulmonary ventilation. What these measures do not account for is the ability of drugs to cause ventilatory instability or interruptions in ventilatory rhythm. Ventilatory instability can be identified by the presence of prolonged end-expiratory pauses or apneic periods. An apneic event has been defined as an apneic period of sufficient duration to cause hypoxia (i.e., decrease in hemoglobin oxygen saturation ≥ 3%). Repeated apneic events are often referred to as intermittent hypoxia. Characterizing ventilatory instability is important since (1) occurrence of apneic events in humans can lead to serious adverse outcomes such as systemic and pulmonary hypertension, cardiac arrhythmia, stroke, CNS dysfunction, metabolic disorders, enhanced tumor growth and death, (2) drugs are known to cause or exacerbate apneic events in humans, and (3) there is a preexisting condition of ventilatory instability referred to as sleep apnea that is prevalent in the human population. Evaluating this new target in respiratory safety pharmacology studies is needed to ensure that the potential for new drugs to cause or exacerbate apneic events can be identified and the impact on patient safety characterized.

Robustness of arterial blood gas analysis for assessment of respiratory safety pharmacology in rats

Whole body plethysmography using unrestrained animals is a common technique for assessing the respiratory risk of new drugs in safety pharmacology studies in rats. However, wide variations in experimental technique make cross laboratory comparison of data difficult and raise concerns that non-appropriate conditions may mask the deleterious effects of test compounds — in particular with suspected respiratory depressants. Therefore, the objective of this study was to evaluate the robustness of arterial blood gas analysis as an alternative to plethysmography in rats. We sought to do this by assessing the effect of different vehicles and times post-surgical catheterization on blood gas measurements, in addition to determining sensitivity to multiple opioids. Furthermore, we determined intra-lab variability from multiple datasets utilizing morphine and generated within a single lab and lastly, inter-lab variability was measured by comparing datasets generated in two separate labs. Overall, our data show that arterial blood gas analysis is a measure that is both flexible in terms of experimental conditions and highly sensitive to respiratory depressants, two key limitations when using plethysmography. As such, our data strongly advocate the adoption of arterial blood gas analysis as an investigative approach to reliably examine the respiratory depressant effects of opioids.

Feasibility and early integration of cardiovascular, CNS and respiratory safety pharmacology endpoints in MTD/DRF toxicology studies

Feasibility and early integration of cardiovascular, CNS and respiratory safety pharmacology endpoints in MTD/DRF toxicology studies

Respiratory safety pharmacology — Current practice and future directions

Respiratory safety pharmacology — Current practice and future directions

Inclusion of neurobehavioural and respiratory safety pharmacology endpoints in the four-week rat general toxicology studies: A CRO perspective

Inclusion of neurobehavioural and respiratory safety pharmacology endpoints in the four-week rat general toxicology studies: A CRO perspective

Reprint of “Non-invasive measure of respiratory mechanics and conventional respiratory parameters in conscious large animals by high frequency Airwave Oscillometry”

IntroductionA number of drugs in clinical trials are discontinued due to potentially life-threatening airway obstruction. As some drugs may not cause changes in core battery parameters such as tidal volume (Vt), respiratory rate (RR) or minute ventilation (MV), including measurements of respiratory mechanics in safety pharmacology studies represents an opportunity for design refinement. The present study aimed to test a novel non-invasive methodology to concomitantly measure respiratory system resistance (Rrs) and conventional respiratory parameters (Vt, RR, MV) in conscious Beagle dogs and cynomolgus monkeys. MethodsAn Airwave Oscillometry system (tremoFlo; THORASYS Inc., Montreal, Canada) was used to concomitantly assess Rrs and conventional respiratory parameters before and after intravenous treatment with a bronchoactive agent. Respiratory mechanics measurements were performed by applying a short (i.e. 16s) single high frequency (19Hz) waveform at the subject's airway opening via a face mask. During measurements, pressure and flow signals were recorded. After collection of baseline measurements, methacholine was administered intravenously to Beagle dogs (n=6) and cynomolgus monkeys (n=4) at 8 and 68μg/kg, respectively. ResultsIn dogs, methacholine induced significant increases in Vt, RR and MV while in monkeys, it only augmented RR. A significant increase in Rrs was observed after methacholine administration in both species with mean percentage peak increases from baseline of 88 (53)% for dogs and 28 (16)% for cynomolgus monkeys. ConclusionAirwave Oscillometry appears to be a promising non-invasive methodology to enable respiratory mechanics measurements in conscious large animals, a valuable refinement in respiratory safety pharmacology.

Non-invasive measure of respiratory mechanics and conventional respiratory parameters in conscious large animals by high frequency Airwave Oscillometry

IntroductionA number of drugs in clinical trials are discontinued due to potentially life-threatening airway obstruction. As some drugs may not cause changes in core battery parameters such as tidal volume (Vt), respiratory rate (RR) or minute ventilation (MV), including measurements of respiratory mechanics in safety pharmacology studies represents an opportunity for design refinement. The present study aimed to test a novel non-invasive methodology to concomitantly measure respiratory system resistance (Rrs) and conventional respiratory parameters (Vt, RR, MV) in conscious Beagle dogs and cynomolgus monkeys. MethodsAn Airwave Oscillometry system (tremoFlo; THORASYS Inc., Montreal, Canada) was used to concomitantly assess Rrs and conventional respiratory parameters before and after intravenous treatment with a bronchoactive agent. Respiratory mechanics measurements were performed by applying a short (i.e. 16s) single high frequency (19Hz) waveform at the subject's airway opening via a face mask. During measurements, pressure and flow signals were recorded. After collection of baseline measurements, methacholine was administered intravenously to Beagle dogs (n=6) and cynomolgus monkeys (n=4) at 8 and 68μg/kg, respectively. ResultsIn dogs, methacholine induced significant increases in Vt, RR and MV while in monkeys, it only augmented RR. A significant increase in Rrs was observed after methacholine administration in both species with mean percentage peak increases from baseline of 88 (53)% for dogs and 28 (16)% for cynomolgus monkeys. ConclusionAirwave Oscillometry appears to be a promising non-invasive methodology to enable respiratory mechanics measurements in conscious large animals, a valuable refinement in respiratory safety pharmacology.

Respiratory mechanics: Comparison of Beagle dogs, Göttingen minipigs and Cynomolgus monkeys

IntroductionWhen the no observed adverse effect level (NOAEL) is determined by respiratory safety pharmacology, follow-up studies are warranted and may include airway resistance and compliance. Respiratory mechanics in commonly used large animal species (Beagle dogs, Cynomolgus monkeys, and Göttingen minipigs) were compared. Methods:Eighteen animals were used (3/sex/species) in an anesthetized model (propofol infusion) with pancuronium as a neuromuscular blocker. Parameters of respiratory mechanics were evaluated at baseline and at peak drug effect. Resistance (Rrs) and elastance (Ers) were measured by applying a single frequency forced oscillation (0.5 Hz) to the subject's airway opening and fitting the flow, volume and pressure data to the single compartment model of the lung. Increasing doses of intravenous (IV) methacholine were administered in all three species, as well as doubling aerosolized concentrations of the same bronchoconstrictor agent before and after inhaled albuterol. Results:The slope of the IV methacholine dose-response curve for Rrs was similar in dogs and monkeys and both species differed from minipigs, which showed greater reactivity. At the highest IV dose tested, minipigs also reached higher levels of bronchoconstriction than the other two species. They were followed, in decreasing order, by dogs and monkeys. Albuterol induced a significant decrease in the slope of the dose-response curve only in dogs and monkeys. Discussion:Scientific literature is available on respiratory mechanics in monkeys and dogs but not in minipigs. Our results suggest that minipigs were more reactive than dogs and monkeys to IV methacholine while less sensitive to inhaled albuterol.

Respiratory safety pharmacology – Current practice and future directions

Current practice in respiratory safety pharmacology generally follows the guidance provided by the ICH document S7A and, in general, focuses on measures of pulmonary ventilation. Respiratory rate, tidal volume and/or a measure of arterial blood gases are the recommended ventilatory measurement parameters. Although these parameters will provide a measure of ventilation, other ventilatory parameters, which can provide mechanistic insight, should also be considered. Such parameters include inspiratory and expiratory times and flows and apneic time. Stimulation models involving exercise and exposure to elevated CO2 or reduced O2 should also be considered when enhancing measurement sensitivity or quantifying reductions in ventilatory functional reserve are desired. Although ventilatory measurements are capable of assessing the functional status of the respiratory pumping apparatus, such measurements are generally not capable of assessing the status of the other functional component of the respiratory system, namely, the gas exchange unit or lung. To characterize drug-induced effects on the gas exchange unit, measures of airway patency, lung elastic recoil and gas diffusion capacity need to be considered. Thus, a variety of methodologies and measurement endpoints are available for detecting and characterizing drug-induced respiratory dysfunction in animal models and should be considered when designing respiratory safety pharmacology studies.

Super-intervals: Application to respiratory safety pharmacology data in rats

Super-intervals: Application to respiratory safety pharmacology data in rats

Cardiorespiratory safety evaluation in non-human primates

IntroductionThis study was designed to provide a comprehensive nonclinical respiratory safety pharmacology assessment using respiratory inductance plethysmography (RIP) concomitant with a standard cardiovascular (CV) safety assessment in non-human primates (NHP) in a single cardiorespiratory study. MethodsRIP calibration data were generated in conscious, ketamine-sedated, or propofol-anesthetized NHP to determine the most appropriate method. Calibration accuracy was assessed using a CO2 rebreathe maneuver. Regardless of the technique, the RIP system reliably demonstrated accurate assessment of the CO2 rebreathe response when expressed as a percent change with respect to control. Four male NHP were given single oral doses of vehicle, 1.25 and 5mg/kg test article followed by 20mg/kg repeatedly for 7days. Telemetry-derived cardiovascular parameters (PR, QRS, QT, heart rate corrected QT (QTcR) intervals, blood pressure [BP], and heart rate [HR]) and RIP-derived respiratory parameters (respiration rate [RR], tidal volume [TV], and minute volume [MV]) were determined for 24h pretest, 2h predose and 24h postdose. ResultsA single dose of the test article at 5 or 20mg/kg was associated with slight increases in HR, BP, RR, and MV at 2 to 7h postdose, followed by decreases in HR, RR, TV, and MV at 5–23h postdose. Decreases in HR, RR, TV, and MV were observed following 7days of dosing at 20mg/kg. Slight QTcR prolongation at 1 to 11h postdose was observed following a single dose of 20mg/kg. ConclusionThese data show that the integrated assessment of cardiovascular and respiratory parameters in NHP is achievable continuously for at least 24h postdose. The use of RIP as a method to assess the effects of a novel compound on the respiratory system complements, but does not interfere with, the cardiovascular assessment of new drugs.

Comparison of whole body and head out plethysmography using respiratory stimulant and depressant in conscious rats

IntroductionAssessment of respiratory safety is one of the most important requirements for new chemical entity (ICH Guideline S7A). The aim of the present study was to compare and validate respiratory safety pharmacology models in conscious rats, to find out the most appropriate method for detection of drug-induced adverse effects on respiratory function in preclinical safety studies. MethodsHead out plethysmography and whole body plethysmography methods were used to monitor typical parameters of ventilatory function like respiratory rate (RR), tidal volume (TV), minute volume (MV) and mid expiratory flow (EF50). The effects of respiratory stimulant theophylline (100mg/kg) and respiratory depressant chlordiazepoxide (100mg/kg) were evaluated in both models. Propranolol (60mg/kg) was also used to compare head out and whole body plethysmography because of its bronchoconstrictor effects on airway function. ResultsTheophylline caused a significant increase in TV, EF50 and MV in both whole body and head out plethysmography. In whole body plethysmography, theophylline significantly increased RR, but this increase was not observed in head out plethysmography. Chlordiazepoxide significantly decreased RR, TV, EF50 and MV in head out plethysmography, but it significantly reduced only TV in whole body plethysmography. A significant reduction in TV was observed with propranolol in both whole body and head out plethysmography. DiscussionWe conclude that ventilatory function can be accurately assessed using head out plethysmography compared to whole body plethysmography. Our experimental results of EF50 from non-invasive methods suggest that reliable assessment of airway function demand additional invasive methods.

Strategies to improve sensitivity of respiratory safety pharmacology studies in cynomolgus monkeys using impedance monitored by implantable telemetry

Strategies to improve sensitivity of respiratory safety pharmacology studies in cynomolgus monkeys using impedance monitored by implantable telemetry

Cardiovascular and respiratory safety pharmacology in Göttingen minipigs: Pharmacological characterization

IntroductionSimilarities between pigs and humans support the relevance of Göttingen minipigs for regulatory safety pharmacology. The minipig is the species of choice for cardiovascular safety pharmacology when pivotal repeat toxicology studies are conducted in this species. Methods4 male Göttingen minipigs with cardiovascular telemetry transmitters received intravenous saline, esmolol (0.5, 1, 2, 4 and 8mg/kg), medetomidine (0.04mg/kg), remifentanil (0.5, 1, 2, 4, 8 and 16μg/kg) and dopamine (2, 8, 10, 20, 30 and 50μg/kg/min) and oral sotalol (3 and 10mg/kg). Respiratory monitoring was conducted in 3 male and 3 female Göttingen minipigs receiving intravenous saline and methacholine (0, 3.4, 13.5 and 68μg/kg). ResultsHeart rate (HR) corrected QT was optimal with a method based on analysis of covariance (QTca) followed by Fridericia's standard formula. Esmolol induced a decrease in HR. Medetomidine was associated with an initial hypertension with bradycardia followed by sustained hypotension, bradycadia and prolonged QTc. Remifentanil induced a dose-dependent QTc shortening with an increase in arterial pressures. Sotalol caused a decrease in HR and systolic arterial pressure with an increase in PR and QTc intervals. Dopamine induced an increase in arterial and pulse pressures. Methacholine increased tidal volume, respiratory rate and minute volume. DiscussionThe results suggest that the minipig is a valid alternative to other non-rodent species for cardiovascular and respiratory safety pharmacology studies when this species is justified.

Respiratory safety pharmacology: Concurrent validation of volume, rate, time, flow and ratio variables in conscious male Sprague–Dawley rats

This study compares basic respiratory variables (rate, tidal and minute volumes) with time-, flow- and ratio-derived parameters obtained using head-out plethysmography in rats following administration of reference drugs (isotonic saline, 2.0 mL/kg, IV; albuterol, 400 μg/kg, inhalation; methacholine, 136 μg/kg, IV; and remifentanil, 14 μg/kg, IV) to identify respiratory variables with superior sensitivity. Paired t-tests by block-period, and analysis of covariance (ANCOVA) with baseline as covariate and a posteriori pair-wise comparisons using Dunnett’s test were used. Variations in respiratory parameters observed over time justify the use of a control group in any respiratory safety pharmacology study for inter-groups comparison. Handling-, and slumbering-, induced perturbations were minimal. The system was sensitive and specific to detect changes in respiratory variables related to pharmacologically-induced bronchodilation, bronchoconstriction and central respiratory depression. The standard variables (respiratory rate, tidal and minute volumes) confirmed to be the cornerstone of respiratory safety pharmacology to detect pharmacological changes. Flow-derived parameters appeared as highly valuable complement for interpretation of respiratory response, whereas time- and ratio-derived parameters presented limited added value during interpretation.