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Vernakalant is devoid of proarrhythmic effects in the cAVB dog
Abstracts
University Medical Center Utrecht, Department of Medical Physiology, Utrecht, The Netherlands
doi:10.1016/j.vascn.2014.03.130
0126 Validation of FOB in two rat strains: Crl:CD(SD) vs Crl:WI(Han) rats Maria Pilla, Alessia Guidi, Valentina Pavoni, Luciano Cunego, Philip Gerrard, Nicola Fasdelli Aptuit, Verona, Italy
The most widely used test to identify undesired effects of drugs on the central and the peripheral nervous system is the neurobehavioural observation battery adapted from that first described by Irwin in mice. As a neurobehavioural assessment is based on observations all factors involved need to be controlled and standardised to make the data collected objective, reproducible, reliable and predictive of safety liabilities. Validation studies were conducted with amphetamine and diazepam given orally, in two different strains of rats, Wistar Han (WH) and Sprague Dawley (CD), in order to establish potential behavioural differences in baseline read out and in response to different drugs. The compounds induced their typical and expected transient effects on behaviour, observed both in the home cage and open-arena, and on body temperature. In particular, amphetamine induced a stimulation of the nervous system activities, and marked hyperthermia. Diazepam induced depressive, anxiolytic or sedative effects associated with hypothermia. The effects induced by diazepam were similar in both strains of rats. On the other hand, there were some differences in the effects induced by amphetamine administration; in particular, WH rats were more sensitive to the effects of amphetamine for those parameters defining awareness, while CD rats showed more pronounced effects on mood and body temperature. The present results confirm that the FOB is a very sensitive test to identify neurobehavioural changes induced by compounds. Moreover, these data suggest that care should be taken when choosing the strain of animals, as there may be differences in their sensitivity to test compounds.
TE
DP
Introduction: The cAVB dog and the methoxamine-sensitized rabbit model have revealed conflicting results for several multitarget drugs (K201, AZD1305) in cardiac safety screening. Vernakalant, an atrial specific combined INa/IK blocker, is approved only in Europe. It has been evaluated solely in methoxamine-sensitized rabbits, thus we assessed the proarrhythmic potential of vernakalant in the more sensitive cAVB dog. Methods: Vernakalant was evaluated in ten mongrel dogs (SR: 2 mg/kg; cAVB: 2 + 3 mg/kg). The same dogs were challenged with dofetilide (25 μg/kg) to evaluate TdP inducibility. During the serial experiments the animals were paced from the right ventricular apex (CL 1000 ms). STV was quantified for proarrhythmic risk. Results: In SR (n = 8) vernakalant prolonged QT (265 ± 11 to 312 ± 18 ms p b 0.01**) and PQ (108 ± 8 to 113 ± 5 ms, p b 0.05*). In cAVB (n = 8), 2 mg/kg vernakalant prolonged QT (400 ± 51 to 530 ± 73 ms**) and QRS (95 ± 26 to 102 ± 25 ms**). After a 30 min lag-time, subsequent infusion of 3 mg/kg vernakalant (n = 4) increased QT to a lesser extent (413 ± 34 to 454 ± 27 ms*) while maintaining QRS prolongation (114 ± 18 to 122 ± 20 ms**). Neither dose increased STV. Dofetilide prolonged QT (404 ± 51 to 629 ± 61 ms**) and increased STV (1.0 ± 0.4 to 2.1 ± 1.1 ms*). In both SR and cAVB, no arrhythmias were induced by vernakalant while dofetilide induced TdP arrhythmias in 6/8* cAVB dogs. Conclusion: Vernakalant did not induce arrhythmias. Higher dosages (3 mg/kg) did not prolong QT further whereas negative inotropic effects were starting to become apparent.
OF
Vernakalant is devoid of proarrhythmic effects in the cAVB dog Rosanne Varkevisser, Ralph Tieland, Jet Beekman, Marcel van der Heyden, Marc Vos
analyzed using Offlinesorter (Plexon) software. BMS-X evoked concentration-dependent increases in spike rate in both WT and KO cells, with maximal increase in spike rate occurring at the same concentration in both cell types. Positive and negative control data were similar in both cell types. Because dose dependent increases in spike rate were elicited in KvX KO mouse neurons as well as in WT neurons, the seizurogenicity is likely an off-target effect not relating to the KvX ion channel.
RO
0124
347
EC
doi:10.1016/j.vascn.2014.03.129
0125
RR
Assessment of target involvement in drug-induced seizures using knockout mouse hippocampal neurons and multielectrode arrays Elisabeth Burnett, Jae Kwagh, George Psaltis, Lucy Sun, Hong Shi, Oliver Flint, Paul Levesque
CO
Bristol-Myers Squibb, Princeton, NJ, USA
UN
Drug-induced seizure liability is a significant safety concern that can have a profound negative impact on drug development. BMS-X, a potent and selective inhibitor of the voltage-gated potassium channel X (KvX), and a lead compound in a discovery program, caused seizures in mice, rats and rabbits. Brain and plasma exposures were similar, and since the therapeutic effect is related to KvX inhibition outside of CNS, it was important to determine whether seizures were target related. If so, downstream compounds would have to be optimized for low brain penetration. Using a Multielectrode Array (MEA) in vitro hippocampal seizure liability assay developed in house, we compared field potential recordings of BMS-X in both wild type (WT) and KvX knockout (KO) mouse hippocampal neurons. Primary mouse postnatal day 1 hippocampal neurons were isolated from WT and homozygous KvX KO mice. Cells were dispersed and cultured for 10– 20 days, and spontaneous spiking activity was recorded in the MEA system at 37 °C in serum-free culture medium without perfusion. Cumulative concentration responses were collected, and data was
doi:10.1016/j.vascn.2014.03.131
0127 Anticonvulsant actions of SKa-31 in pilocarpine treated chronic epileptic rats Muhammad Liaquat Raza, Uwe Heinemann Institute of Neurophysiology, Charité Universitätsmedizin, Berlin, Germany Purpose: Pilocarpine-induced status epilepticus or limbic seizure model is use to test activity of new molecules with anticonvulsant potential. In the present study we focused on anticonvulsant effect of SKa-31 (sK-channel opener) in pilocarpine-induced epileptiform activities. Methods: Male Wistar rats (4–5 weeks) were pre-treated with methylscopolamine (1 mg/kg) followed by i.p. administration of
University Medical Center Utrecht, Department of Medical Physiology, Utrecht, The Netherlands
doi:10.1016/j.vascn.2014.03.130
0126 Validation of FOB in two rat strains: Crl:CD(SD) vs Crl:WI(Han) rats Maria Pilla, Alessia Guidi, Valentina Pavoni, Luciano Cunego, Philip Gerrard, Nicola Fasdelli Aptuit, Verona, Italy
The most widely used test to identify undesired effects of drugs on the central and the peripheral nervous system is the neurobehavioural observation battery adapted from that first described by Irwin in mice. As a neurobehavioural assessment is based on observations all factors involved need to be controlled and standardised to make the data collected objective, reproducible, reliable and predictive of safety liabilities. Validation studies were conducted with amphetamine and diazepam given orally, in two different strains of rats, Wistar Han (WH) and Sprague Dawley (CD), in order to establish potential behavioural differences in baseline read out and in response to different drugs. The compounds induced their typical and expected transient effects on behaviour, observed both in the home cage and open-arena, and on body temperature. In particular, amphetamine induced a stimulation of the nervous system activities, and marked hyperthermia. Diazepam induced depressive, anxiolytic or sedative effects associated with hypothermia. The effects induced by diazepam were similar in both strains of rats. On the other hand, there were some differences in the effects induced by amphetamine administration; in particular, WH rats were more sensitive to the effects of amphetamine for those parameters defining awareness, while CD rats showed more pronounced effects on mood and body temperature. The present results confirm that the FOB is a very sensitive test to identify neurobehavioural changes induced by compounds. Moreover, these data suggest that care should be taken when choosing the strain of animals, as there may be differences in their sensitivity to test compounds.
TE
DP
Introduction: The cAVB dog and the methoxamine-sensitized rabbit model have revealed conflicting results for several multitarget drugs (K201, AZD1305) in cardiac safety screening. Vernakalant, an atrial specific combined INa/IK blocker, is approved only in Europe. It has been evaluated solely in methoxamine-sensitized rabbits, thus we assessed the proarrhythmic potential of vernakalant in the more sensitive cAVB dog. Methods: Vernakalant was evaluated in ten mongrel dogs (SR: 2 mg/kg; cAVB: 2 + 3 mg/kg). The same dogs were challenged with dofetilide (25 μg/kg) to evaluate TdP inducibility. During the serial experiments the animals were paced from the right ventricular apex (CL 1000 ms). STV was quantified for proarrhythmic risk. Results: In SR (n = 8) vernakalant prolonged QT (265 ± 11 to 312 ± 18 ms p b 0.01**) and PQ (108 ± 8 to 113 ± 5 ms, p b 0.05*). In cAVB (n = 8), 2 mg/kg vernakalant prolonged QT (400 ± 51 to 530 ± 73 ms**) and QRS (95 ± 26 to 102 ± 25 ms**). After a 30 min lag-time, subsequent infusion of 3 mg/kg vernakalant (n = 4) increased QT to a lesser extent (413 ± 34 to 454 ± 27 ms*) while maintaining QRS prolongation (114 ± 18 to 122 ± 20 ms**). Neither dose increased STV. Dofetilide prolonged QT (404 ± 51 to 629 ± 61 ms**) and increased STV (1.0 ± 0.4 to 2.1 ± 1.1 ms*). In both SR and cAVB, no arrhythmias were induced by vernakalant while dofetilide induced TdP arrhythmias in 6/8* cAVB dogs. Conclusion: Vernakalant did not induce arrhythmias. Higher dosages (3 mg/kg) did not prolong QT further whereas negative inotropic effects were starting to become apparent.
OF
Vernakalant is devoid of proarrhythmic effects in the cAVB dog Rosanne Varkevisser, Ralph Tieland, Jet Beekman, Marcel van der Heyden, Marc Vos
analyzed using Offlinesorter (Plexon) software. BMS-X evoked concentration-dependent increases in spike rate in both WT and KO cells, with maximal increase in spike rate occurring at the same concentration in both cell types. Positive and negative control data were similar in both cell types. Because dose dependent increases in spike rate were elicited in KvX KO mouse neurons as well as in WT neurons, the seizurogenicity is likely an off-target effect not relating to the KvX ion channel.
RO
0124
347
EC
doi:10.1016/j.vascn.2014.03.129
0125
RR
Assessment of target involvement in drug-induced seizures using knockout mouse hippocampal neurons and multielectrode arrays Elisabeth Burnett, Jae Kwagh, George Psaltis, Lucy Sun, Hong Shi, Oliver Flint, Paul Levesque
CO
Bristol-Myers Squibb, Princeton, NJ, USA
UN
Drug-induced seizure liability is a significant safety concern that can have a profound negative impact on drug development. BMS-X, a potent and selective inhibitor of the voltage-gated potassium channel X (KvX), and a lead compound in a discovery program, caused seizures in mice, rats and rabbits. Brain and plasma exposures were similar, and since the therapeutic effect is related to KvX inhibition outside of CNS, it was important to determine whether seizures were target related. If so, downstream compounds would have to be optimized for low brain penetration. Using a Multielectrode Array (MEA) in vitro hippocampal seizure liability assay developed in house, we compared field potential recordings of BMS-X in both wild type (WT) and KvX knockout (KO) mouse hippocampal neurons. Primary mouse postnatal day 1 hippocampal neurons were isolated from WT and homozygous KvX KO mice. Cells were dispersed and cultured for 10– 20 days, and spontaneous spiking activity was recorded in the MEA system at 37 °C in serum-free culture medium without perfusion. Cumulative concentration responses were collected, and data was
doi:10.1016/j.vascn.2014.03.131
0127 Anticonvulsant actions of SKa-31 in pilocarpine treated chronic epileptic rats Muhammad Liaquat Raza, Uwe Heinemann Institute of Neurophysiology, Charité Universitätsmedizin, Berlin, Germany Purpose: Pilocarpine-induced status epilepticus or limbic seizure model is use to test activity of new molecules with anticonvulsant potential. In the present study we focused on anticonvulsant effect of SKa-31 (sK-channel opener) in pilocarpine-induced epileptiform activities. Methods: Male Wistar rats (4–5 weeks) were pre-treated with methylscopolamine (1 mg/kg) followed by i.p. administration of