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Non-invasive blood pressure monitoring in ambulatory beagle dogs
e42
Abstracts
subclinical seizures occurred in the rat. Six Sprague-Dawley rats were implanted with 2-channel EEG telemetry units fixed over the frontal and occipital cortices. Rats were administered 5 or 75 mg/kg SCH A by oral gavage daily for 7 days. Exposure at 75 mg/kg matched exposure at which convulsions were seen in monkeys. EEG and behavior were recorded daily pre-dose and for 2 h post-dose (Tmax). No behavioral or EEG abnormalities were seen over the 7 days of dosing. Three Cynomolgus monkeys were implanted with 2-channel EEG electrodes fixed over each temporal cortex. Monkeys were administered 75 mg/ kg SCH A, a dose that previously elicited convulsions, by oral gavage daily for 7 days followed by 4 days wash-out. EEG activity was recorded for 23 h each day. Behavior was observed via videocamera and recorded once an hour. SCH A cause abnormal EEG waveforms during the waking state in all animals: sharp waves, slow waves, spikes and in one animal, seizure. Abnormal behavior was also observed in all animals including hunched posture and inactivity. During wash-out, the frequency of abnormal behaviors and EEG waveforms decreased dramatically. Thus, SCH A was shown to cause seizure in monkeys but not rats. EEG was useful in characterizing the onset, frequency and pattern of abnormal waveforms and for determining that subclinical seizures did not occur in the rat.
doi:10.1016/j.vascn.2010.11.141
Poster Number: 138 Board Number: 77 Integration of hemodynamic endpoints into toxicology studies: Torcetrapib and high definition oscillometry (HDO) in cynomolgus monkeys Barthel Schmelting, Marc Niehoff, Gerhard F. Weinbauer
Poster Number: 139 Board Number: 78 High definition oscillometry (HDO): A novel technique for non-invasive blood pressure measurements in beagle dogs Andrea Z. Mitchell, Carrie McMahon, R. Dustan Sarazan Covance Laboratories, Madison, WI, United States Dogs are commonly used in toxicological research for the evaluation of drug effects on the cardiovascular system. Accurate and reproducible determination of blood pressure (BP) in conscious, manually restrained dogs is a challenge with current non-invasive cuff techniques. The HDO technique enables real time measurements with immediate visual feedback (via PC screen) on data validity. HDO measurements are considerably faster (~ 15 sec) than other cuff methods. HDO and Cardell BP Monitor Model 9401 measurements were compared for accuracy and reliability with simultaneously recorded direct blood pressure data from telemetry implants. Six dogs implanted with telemetry transmitters were used and BP data were compared under manual constraint. Two different technicians took HDO measurements on the same dogs to determine inter-staff robustness. Additional measurements were performed with HDO and Cardell in the absence and presence of a BP lowering drug (Hexamethonium). Systolic, diastolic, mean arterial pressure, and pulse rate were determined. Correlation coefficients for the interstaff robustness phase revealed that training on the HDO equipment is important for accurate measurements. Correlation coefficients were generally higher for HDO-Telemetry than Cardell-Telemetry comparisons, indicating that this novel, non-invasive technique produces reliable blood pressure data and is able to detect druginduced hemodynamic changes. In conclusion, HDO provides an alternative BP measurement technique when invasive techniques are not warranted.
Covance Laboratories GmbH, Muenster, Germany doi:10.1016/j.vascn.2010.11.143 Torcetrapib (Tor) is an experimental cholesterol ester transfer protein inhibitor that was terminated prematurely for imbalanced allcause clinical mortality and major cardiovascular events. This highlights the need to identify off-target toxicities early in drug development. We compared Tor-induced mean arterial pressure increases (MAP) by HDO and telemetry in cynomolgus monkeys. Measurements were performed following Tor (30 mg/kg) in a toxicology setting with conscious, restrained animals (n = 18) by HDO and in unrestrained, telemeterized monkeys (n = 6). These were also measured in parallel by standard oscillometry, HDO and telemetry under restraint. The range of intraindividual standard deviation (SD) in MAP for a given time frame were similar for HDO and Telemetry (e.g. max SD 5.1 and 7.9 resp.) confirming the precision of HDO whereas standard oscillometry showed high intraindividual variance (up to 19.9 SD). In a safety pharmacology setting with telemeterized monkeys, MAP was elevated around 10 mmHg post dosing. In 9/12 monkeys which were well trained and adapted to handling for HDO, MAP increased 10.4% (range 4.1 – 22.9%) after dosing. Importantly, the vigilance status and temperament of the animals during measurement was pivotal, as stressrelated MAP increases masked potential drug-related effects. This was most prominent in non-trained individuals as the hypertensive effect of Tor could only be detected in 1/6 monkeys. Using precise and sensitive HDO, avoidance of stress or handling associated MAP increases is crucial when evaluating drug related hemodynamic changes.
doi:10.1016/j.vascn.2010.11.142
Poster Number: 140 Board Number: 79 Non-invasive blood pressure monitoring in ambulatory beagle dogs Anne-Marie Betata, Jean-Gerard Napoleonib, Guillaume Frogeta, Alain Simonnarda a
Centre International de Toxicologie (CIT), Evreux cedex, France EMKA Technologies, Paris, France
b
Development of biologics for which Safety Pharmacology (SP) standard study designs are not well adapted led pharmaceutical industries to develop ways to integrate SP endpoints in toxicology studies to fulfill ICH guidelines. For this purpose, external telemetry, linked to a camera video, allows today continuous recording of ECG, respiration and behavior in ambulatory non-rodent models. One of the major physiological signals missing until now was arterial blood pressure (ABP) for which a surgical approach was required. The aim of this study was to evaluate the feasibility and efficacy of a novel technique of non invasive blood pressure (NIBP) recording by telemetry developed by EMKA Technologies. The study consisted firstly in evaluating the habituation of dogs to the recording equipment. Then, the second phase was to validate the model for evaluation of the potential of a drug to modify ABP. Then a crossvalidation study was performed with concomitant recording of ABP signals with an implanted catheter (internal telemetry IntT) and with the NIBP system (external telemetry ExtT). Four beagle dogs
Abstracts
implanted with telemetric devices were used. After habituation to the external telemetry equipment, they were treated with a positive control, Prazosin, well known to modify ABP. Decreases in systolic (IntT = -24%, ExtT = -16%) and mean ABP (IntT = -24%, ExtT = -25%) were demonstrated with both techniques. This study demonstrates that NIBP measured by external telemetry is an appropriate alternative method for recording ABP over long periods without preliminary surgery in the dogs. doi:10.1016/j.vascn.2010.11.144
Poster Number: 141 Board Number: 80 Rat to human translation of effects of cardiac sodium channel blockers Stella P. Worton, Bethan K. Lawton, Chris P. Doe, Nick McMahon GlaxoSmithKline, The Frythe, Welwyn, United Kingdom Inhibition of cardiac sodium channels can cause conduction slowing and cardiovascular collapse. The aim of this work was to assess the conscious rat model for detecting sodium channel block effects and the models translation to human cardiovascular safety. Cardiovascular and electrocardiogram parameters were recorded from conscious male rats (CRL:CD) previously implanted with DSI telemetry transmitters. Rats received either flecainide, a class Ic Na channel blocker (n = 6, 553-672 g) at 5, 15 and 45 mg/kg p.o, or mexiletine, a class Ib Na+ channel blocker (n = 6, 479-585 g) at 5, 15, 45 and 90 mg/kg p.o, respectively, each in a dose rising paradigm. A separate group of rats (n = 3 per compound, 511-708 g) were used for determination of pharmacokinetics. Flecainide at 5, 15 and 45 mg/kg (with free Cmax values of 0.5 ± 0.0, 1.7 ± 0.1 and 2.7 ± 0.1 μM) increased QRS by 10.9 ± 3.5, 19.4 ± 4.1 and 44.3 ± 15.5%, respectively. Mexiletine only increased QRS (34.3 ± 19.2%) at the highest dose tested, 90 mg/kg, p.o. (with a free Cmax value of 1.6 ± 0.7 μM) in the rat. In human, flecainide at free Cmax values of 0.6 and 0.8 μM increased QRS complex duration by up to 23 and 24% respectively [Deneer et al., 2004 and Webb et al., 1986] whilst mexiletine at a free Cmax value of 1.7 μM increased QRS complex duration ranging between 4 to 11.5% [Sadanaga et al., 1993]. Comparison with human pharmacokinetic and pharmacodynamic data suggests this is an appropriate in vivo model for detection of cardiac sodium channel block for candidate selection of compounds.
doi:10.1016/j.vascn.2010.11.145
Poster Number: 142 Board Number: 81 Is the guinea-pig a suitable model for arterial blood pressure assessment? Nichole Byrne, Anthea Sutton, Audrey Sharp, Sotereos Gates, Claire Truswell, Andrea Stanton, Aileen Milne, Kirsty Macfarlane, Sarra Laycock Aptuit Ltd., Riccarton, Edinburgh, United Kingdom Previously we have refined the surgical approach for telemetering guinea-pigs to provide not only a robust model for screening novel agents for their potential to prolong QT interval but also their ability
e43
to alter arterial blood pressure. We reported initial success with our surgical method whereby the telemetry implant was placed subcutaneously on the back of the neck with the ECG leads secured in the lead II configuration and the blood pressure catheter advanced into the carotid artery. However, this success did not always prove to be reproducible in the long term. While the Lead II ECG waveforms were consistently of high quality, arterial blood pressure data were variable with unphysiological values often reported. This was considered to be due to the catheter tip not being in its optimum recording position in the aortic arch. The surgical procedure was modified further to allow intra-peritoneal placement of the implant body and subsequent cannulation of the femoral artery. Following a suitable post-surgical recovery period, arterial blood pressures were recorded from the animals and found to be comparable to values documented in the literature. A pressor agent was administered to the guinea-pigs to assess the suitability of this model to reliably detect changes in arterial blood pressure. Data were compared to that acquired from guinea-pigs implanted using the subcutaneous method and also from rats, the species typically used for the early assessment of a compound's ability to alter arterial blood pressure. The benefits of each model will be discussed. doi:10.1016/j.vascn.2010.11.146
Poster Number: 143 Board Number: 82 Telemetry in the guinea-pig: A model for early safety evaluation of both haemodynamic and electrocardiographic parameters Eric Delpya, Klaus Asger Rytvedb, Eva Dam Christoffersenb, Anne Kruse Lykkebergb, Kim Grimstrup Madsenb, Fabrice Infantia, Mathilde Loiseaua, Christopher Drieu La Rochellea a
Biotrial Pharmacology, Rennes, France NeuroSearch A/S, Ballerup, Denmark
b
The guinea-pig (GP) recently emerged as a species possessing a good predictive value, in particular to evaluate the potential for delayed ventricular repolarization. We therefore aimed to set up a model of telemetered GP to allow the evaluation of a series of compounds to be performed in conscious freely moving animals, according to ICH S7A and S7B guidelines. Male Dunkin-Hartley GP were instrumented under isoflurane anaesthesia with a telemetry device (C50-PXT, DSI). The catheter was introduced into the aorta. The implant body as well as ECG leads were placed subcutaneously. Reliable determination of arterial pressure (AP), heart rate (HR) and ECG signals were performed in healthy GP up to 8 months after the initial surgery. Nifedipine (10 mg/kg p.o.) and sotalol (100 mg/kg p. o.) were used in this model to ensure pharmacological validation. A series of 4 early program compounds (NS-A, NS-B, NS-C and NS-D) were tested in the model after a single oral administration and hemodynamic parameters were monitored over 24 h. Satellite GP were used to evaluate drug plasma concentration over a 6-h period after oral dosing. NS-A had no effects on AP but decreased HR and increased both QT and QTc. NS-B induced a marked decrease in AP associated with a reflex tachycardia but had no effects on QTc. NS-C had no effects on AP, HR or QTc. NS-D had no effects on AP but increased HR, QT and QTc. These results show that the model of telemetry in the guinea-pig is appropriate for an early de-risking strategy in drug discovery.
doi:10.1016/j.vascn.2010.11.147
Abstracts
subclinical seizures occurred in the rat. Six Sprague-Dawley rats were implanted with 2-channel EEG telemetry units fixed over the frontal and occipital cortices. Rats were administered 5 or 75 mg/kg SCH A by oral gavage daily for 7 days. Exposure at 75 mg/kg matched exposure at which convulsions were seen in monkeys. EEG and behavior were recorded daily pre-dose and for 2 h post-dose (Tmax). No behavioral or EEG abnormalities were seen over the 7 days of dosing. Three Cynomolgus monkeys were implanted with 2-channel EEG electrodes fixed over each temporal cortex. Monkeys were administered 75 mg/ kg SCH A, a dose that previously elicited convulsions, by oral gavage daily for 7 days followed by 4 days wash-out. EEG activity was recorded for 23 h each day. Behavior was observed via videocamera and recorded once an hour. SCH A cause abnormal EEG waveforms during the waking state in all animals: sharp waves, slow waves, spikes and in one animal, seizure. Abnormal behavior was also observed in all animals including hunched posture and inactivity. During wash-out, the frequency of abnormal behaviors and EEG waveforms decreased dramatically. Thus, SCH A was shown to cause seizure in monkeys but not rats. EEG was useful in characterizing the onset, frequency and pattern of abnormal waveforms and for determining that subclinical seizures did not occur in the rat.
doi:10.1016/j.vascn.2010.11.141
Poster Number: 138 Board Number: 77 Integration of hemodynamic endpoints into toxicology studies: Torcetrapib and high definition oscillometry (HDO) in cynomolgus monkeys Barthel Schmelting, Marc Niehoff, Gerhard F. Weinbauer
Poster Number: 139 Board Number: 78 High definition oscillometry (HDO): A novel technique for non-invasive blood pressure measurements in beagle dogs Andrea Z. Mitchell, Carrie McMahon, R. Dustan Sarazan Covance Laboratories, Madison, WI, United States Dogs are commonly used in toxicological research for the evaluation of drug effects on the cardiovascular system. Accurate and reproducible determination of blood pressure (BP) in conscious, manually restrained dogs is a challenge with current non-invasive cuff techniques. The HDO technique enables real time measurements with immediate visual feedback (via PC screen) on data validity. HDO measurements are considerably faster (~ 15 sec) than other cuff methods. HDO and Cardell BP Monitor Model 9401 measurements were compared for accuracy and reliability with simultaneously recorded direct blood pressure data from telemetry implants. Six dogs implanted with telemetry transmitters were used and BP data were compared under manual constraint. Two different technicians took HDO measurements on the same dogs to determine inter-staff robustness. Additional measurements were performed with HDO and Cardell in the absence and presence of a BP lowering drug (Hexamethonium). Systolic, diastolic, mean arterial pressure, and pulse rate were determined. Correlation coefficients for the interstaff robustness phase revealed that training on the HDO equipment is important for accurate measurements. Correlation coefficients were generally higher for HDO-Telemetry than Cardell-Telemetry comparisons, indicating that this novel, non-invasive technique produces reliable blood pressure data and is able to detect druginduced hemodynamic changes. In conclusion, HDO provides an alternative BP measurement technique when invasive techniques are not warranted.
Covance Laboratories GmbH, Muenster, Germany doi:10.1016/j.vascn.2010.11.143 Torcetrapib (Tor) is an experimental cholesterol ester transfer protein inhibitor that was terminated prematurely for imbalanced allcause clinical mortality and major cardiovascular events. This highlights the need to identify off-target toxicities early in drug development. We compared Tor-induced mean arterial pressure increases (MAP) by HDO and telemetry in cynomolgus monkeys. Measurements were performed following Tor (30 mg/kg) in a toxicology setting with conscious, restrained animals (n = 18) by HDO and in unrestrained, telemeterized monkeys (n = 6). These were also measured in parallel by standard oscillometry, HDO and telemetry under restraint. The range of intraindividual standard deviation (SD) in MAP for a given time frame were similar for HDO and Telemetry (e.g. max SD 5.1 and 7.9 resp.) confirming the precision of HDO whereas standard oscillometry showed high intraindividual variance (up to 19.9 SD). In a safety pharmacology setting with telemeterized monkeys, MAP was elevated around 10 mmHg post dosing. In 9/12 monkeys which were well trained and adapted to handling for HDO, MAP increased 10.4% (range 4.1 – 22.9%) after dosing. Importantly, the vigilance status and temperament of the animals during measurement was pivotal, as stressrelated MAP increases masked potential drug-related effects. This was most prominent in non-trained individuals as the hypertensive effect of Tor could only be detected in 1/6 monkeys. Using precise and sensitive HDO, avoidance of stress or handling associated MAP increases is crucial when evaluating drug related hemodynamic changes.
doi:10.1016/j.vascn.2010.11.142
Poster Number: 140 Board Number: 79 Non-invasive blood pressure monitoring in ambulatory beagle dogs Anne-Marie Betata, Jean-Gerard Napoleonib, Guillaume Frogeta, Alain Simonnarda a
Centre International de Toxicologie (CIT), Evreux cedex, France EMKA Technologies, Paris, France
b
Development of biologics for which Safety Pharmacology (SP) standard study designs are not well adapted led pharmaceutical industries to develop ways to integrate SP endpoints in toxicology studies to fulfill ICH guidelines. For this purpose, external telemetry, linked to a camera video, allows today continuous recording of ECG, respiration and behavior in ambulatory non-rodent models. One of the major physiological signals missing until now was arterial blood pressure (ABP) for which a surgical approach was required. The aim of this study was to evaluate the feasibility and efficacy of a novel technique of non invasive blood pressure (NIBP) recording by telemetry developed by EMKA Technologies. The study consisted firstly in evaluating the habituation of dogs to the recording equipment. Then, the second phase was to validate the model for evaluation of the potential of a drug to modify ABP. Then a crossvalidation study was performed with concomitant recording of ABP signals with an implanted catheter (internal telemetry IntT) and with the NIBP system (external telemetry ExtT). Four beagle dogs
Abstracts
implanted with telemetric devices were used. After habituation to the external telemetry equipment, they were treated with a positive control, Prazosin, well known to modify ABP. Decreases in systolic (IntT = -24%, ExtT = -16%) and mean ABP (IntT = -24%, ExtT = -25%) were demonstrated with both techniques. This study demonstrates that NIBP measured by external telemetry is an appropriate alternative method for recording ABP over long periods without preliminary surgery in the dogs. doi:10.1016/j.vascn.2010.11.144
Poster Number: 141 Board Number: 80 Rat to human translation of effects of cardiac sodium channel blockers Stella P. Worton, Bethan K. Lawton, Chris P. Doe, Nick McMahon GlaxoSmithKline, The Frythe, Welwyn, United Kingdom Inhibition of cardiac sodium channels can cause conduction slowing and cardiovascular collapse. The aim of this work was to assess the conscious rat model for detecting sodium channel block effects and the models translation to human cardiovascular safety. Cardiovascular and electrocardiogram parameters were recorded from conscious male rats (CRL:CD) previously implanted with DSI telemetry transmitters. Rats received either flecainide, a class Ic Na channel blocker (n = 6, 553-672 g) at 5, 15 and 45 mg/kg p.o, or mexiletine, a class Ib Na+ channel blocker (n = 6, 479-585 g) at 5, 15, 45 and 90 mg/kg p.o, respectively, each in a dose rising paradigm. A separate group of rats (n = 3 per compound, 511-708 g) were used for determination of pharmacokinetics. Flecainide at 5, 15 and 45 mg/kg (with free Cmax values of 0.5 ± 0.0, 1.7 ± 0.1 and 2.7 ± 0.1 μM) increased QRS by 10.9 ± 3.5, 19.4 ± 4.1 and 44.3 ± 15.5%, respectively. Mexiletine only increased QRS (34.3 ± 19.2%) at the highest dose tested, 90 mg/kg, p.o. (with a free Cmax value of 1.6 ± 0.7 μM) in the rat. In human, flecainide at free Cmax values of 0.6 and 0.8 μM increased QRS complex duration by up to 23 and 24% respectively [Deneer et al., 2004 and Webb et al., 1986] whilst mexiletine at a free Cmax value of 1.7 μM increased QRS complex duration ranging between 4 to 11.5% [Sadanaga et al., 1993]. Comparison with human pharmacokinetic and pharmacodynamic data suggests this is an appropriate in vivo model for detection of cardiac sodium channel block for candidate selection of compounds.
doi:10.1016/j.vascn.2010.11.145
Poster Number: 142 Board Number: 81 Is the guinea-pig a suitable model for arterial blood pressure assessment? Nichole Byrne, Anthea Sutton, Audrey Sharp, Sotereos Gates, Claire Truswell, Andrea Stanton, Aileen Milne, Kirsty Macfarlane, Sarra Laycock Aptuit Ltd., Riccarton, Edinburgh, United Kingdom Previously we have refined the surgical approach for telemetering guinea-pigs to provide not only a robust model for screening novel agents for their potential to prolong QT interval but also their ability
e43
to alter arterial blood pressure. We reported initial success with our surgical method whereby the telemetry implant was placed subcutaneously on the back of the neck with the ECG leads secured in the lead II configuration and the blood pressure catheter advanced into the carotid artery. However, this success did not always prove to be reproducible in the long term. While the Lead II ECG waveforms were consistently of high quality, arterial blood pressure data were variable with unphysiological values often reported. This was considered to be due to the catheter tip not being in its optimum recording position in the aortic arch. The surgical procedure was modified further to allow intra-peritoneal placement of the implant body and subsequent cannulation of the femoral artery. Following a suitable post-surgical recovery period, arterial blood pressures were recorded from the animals and found to be comparable to values documented in the literature. A pressor agent was administered to the guinea-pigs to assess the suitability of this model to reliably detect changes in arterial blood pressure. Data were compared to that acquired from guinea-pigs implanted using the subcutaneous method and also from rats, the species typically used for the early assessment of a compound's ability to alter arterial blood pressure. The benefits of each model will be discussed. doi:10.1016/j.vascn.2010.11.146
Poster Number: 143 Board Number: 82 Telemetry in the guinea-pig: A model for early safety evaluation of both haemodynamic and electrocardiographic parameters Eric Delpya, Klaus Asger Rytvedb, Eva Dam Christoffersenb, Anne Kruse Lykkebergb, Kim Grimstrup Madsenb, Fabrice Infantia, Mathilde Loiseaua, Christopher Drieu La Rochellea a
Biotrial Pharmacology, Rennes, France NeuroSearch A/S, Ballerup, Denmark
b
The guinea-pig (GP) recently emerged as a species possessing a good predictive value, in particular to evaluate the potential for delayed ventricular repolarization. We therefore aimed to set up a model of telemetered GP to allow the evaluation of a series of compounds to be performed in conscious freely moving animals, according to ICH S7A and S7B guidelines. Male Dunkin-Hartley GP were instrumented under isoflurane anaesthesia with a telemetry device (C50-PXT, DSI). The catheter was introduced into the aorta. The implant body as well as ECG leads were placed subcutaneously. Reliable determination of arterial pressure (AP), heart rate (HR) and ECG signals were performed in healthy GP up to 8 months after the initial surgery. Nifedipine (10 mg/kg p.o.) and sotalol (100 mg/kg p. o.) were used in this model to ensure pharmacological validation. A series of 4 early program compounds (NS-A, NS-B, NS-C and NS-D) were tested in the model after a single oral administration and hemodynamic parameters were monitored over 24 h. Satellite GP were used to evaluate drug plasma concentration over a 6-h period after oral dosing. NS-A had no effects on AP but decreased HR and increased both QT and QTc. NS-B induced a marked decrease in AP associated with a reflex tachycardia but had no effects on QTc. NS-C had no effects on AP, HR or QTc. NS-D had no effects on AP but increased HR, QT and QTc. These results show that the model of telemetry in the guinea-pig is appropriate for an early de-risking strategy in drug discovery.
doi:10.1016/j.vascn.2010.11.147