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Intravenous bolus on rat respiratory study: What is the limit?
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Journal of Pharmacological and Toxicological Methods 58 (2008) 147–178
Respiratory assessment in tethered conscious beagle dogs Philip R. Atterson, K. Kearney, K. Landis, S. Castellucci (WIL Research Laboratories, LLC, Ashland, OH, USA) The assessment of potentially unwanted drug effects on respiratory function are commonly performed in conscious rodents to satisfy the requirements of the ICH S7A guidelines. However, there are certain circumstances whereby the rat may not be a suitable model and an alternative species is required. Models using sling trained conscious beagle dogs have been used for this purpose, although the sling apparatus may have a compromising effect on thoracic movement. This method describes the use of a tethered leash system designed to allow animals to be restrained whilst allowing free thoracic movement. Following acclimation to the restraining apparatus, a neoprene face mask and nylon muzzle are placed over the snout and mouth of the dog. An additional conditioning period is then allowed during which the time of each session can be increased to equate to the projected on-study restraint period. Respiratory activity is then measured by the use of a pneumotach to detect the flow of air in and out of the mask system in response to the animal's thoracic movement. The pneumotach signals are detected by a variable reluctance transducer, amplified and recorded using a suitable data acquisition package. We measured the changes in respiratory frequency (RF), tidal volume (TV) and minute volume (MV) of groups of 4 male beagle dogs following intramuscular administration of either vehicle (0.9% w/v saline) or morphine sulfate at doses of 0.25, 0.5 or 1.0 mg/kg. Data were filtered so that RF N 100 bpm or TV N 500 mL were excluded from the analysis. Respiratory parameters were collected for one hour prior to dosing and continuously for 2 h post dose. Additional 30 min segments were collected around 4 and 6 h post dose. For each parameter, 15-min averages were analyzed. As expected, treatment with morphine resulted in depression of the measured respiratory parameters. This data suggests that the use of the tethered conscious beagle dog is a viable alternative in situations where the rat is not a suitable species for assessment of respiratory function. doi:10.1016/j.vascn.2008.05.113
suggest that both IV boluses were excessive and overloaded animals. 10 mL/kg bolus was compensated by TV increase and did not change MV. In contrast, 20 mL/kg bolus was not completely compensated. More studies are needed to determine the DV that does not affect RP. doi:10.1016/j.vascn.2008.05.114 Refinement of the charcoal meal GI study: Reduction in the fasting period required Helen Prior, L. Ewart, E. Fantham, P. Pimlott, F. Cowell, J.P. Valentin (Safety Assessment UK, AstraZeneca R&D, Alderley Park, Macclesfield, UK) Rodents are routinely fasted overnight (~18 h) prior to charcoal meal GI studies. Prolonged fasting can cause stress, aggression (requiring single-housing), bodyweight loss and more severe clinical signs with test compounds. However, stomachs may be empty after shorter fasts. We investigated whether reduced fasting periods impact on study outcome. Male Han Wistar rats (228–259 g) or CD-1 mice (35–51 g) were fasted for 0, 3, 6 or 18 h prior to dosing (n = 8 per group). Animals were dosed orally with vehicle or atropine (20/30 mg/kg for rats/mice) 1 h prior to a charcoal meal, then killed 15 min later. The % intestinal transit (IT) of charcoal and weight of stomach contents (index of gastric emptying: GE) were measured. Rats fasted for 18 h had a change in bodyweight of − 7%, compared to + 1, + 1 or + 2% after 6, 3 or 0 h fasts respectively. Mice fasted for 18 h had a change in bodyweight of − 14%, compared to − 6, 0 or + 1% after 6, 3 or 0 h fasts respectively. Rats fasted for 18 or 6 h had a group median IT of 59% or 64% and a GE of 1.1 g or 0.6 g (p N 0.05 Mann Whitney test; vehicle) compared to IT of 39% or 36% and GE of 2.5 g or 2.9 g (atropine). Mice fasted for 18 or 6 h had a group median IT of 38% or 45% and a GE of 0.2 g or 0.4 g (p N 0.05; vehicle) compared to IT of 31% or 31% and GE of 0.2 or 0.4 g (atropine). 0 or 3 h fasts led to similar, but more variable data. Charcoal was still clearly visible when food was present in the intestines. In conclusion, fasting rodents for 6 h gives similar results to overnight fasting and has less effect on bodyweight. It also enables group-housing for mice.
Intravenous bolus on rat respiratory study: What is the limit?
doi:10.1016/j.vascn.2008.05.115
Philip R. Atterson, M. Soloviev, K. Kearney, K. Landis, S. Castellucci (WIL Research Laboratories, LLC, Ashland, OH, USA)
Detection of drug-induced emetic effects in mice
Some drug candidates require intravenous (IV) administration. Substantial IV dosing volume (DV) by itself does trigger changes in respiratory parameters (RP). To evaluate RP in response to DV, male rats (9–12 week) were acclimated to the restraint, and studied in the head-out plethysmograph (Buxco Electronics) pre-dose and for 6 h after dosing with saline. The first group was dosed by oral gavage (DV — 10 mL/kg); the second group was dosed subcutaneously (DV — 2 mL/kg); the third group (10bG) was dosed with 10 mL/kg IV bolus over ~2 min; the fourth group (10iG) was dosed by IV infusion (DV — 10 mL/kg over ~30 min); the fifth group (20bG) was dosed with 20 mL/ kg IV bolus over ~ 2 min. Respiratory frequency (RF), tidal volume (TV) and minute volume (MV) were collected using Ponemah Physiology Platform (LDS, Valley View, OH). 15-min averages were analyzed. Immediately after dosing all groups showed an increase in RF by 20–40% compared to baseline; TV and MV was also increased except for 10iG, which were not removed from the plethysmograph for dosing and thus did not demonstrate excessive initial excitement. Within 30–45 min all RP were close to the baseline in all groups, except 10bG (increased TV) and 20bG (RF and MV remained 10–20% higher than at baseline and other groups for at least 4 h). Results
Kentaro Ando, K. Takagi (Mitsubishi Pharma Corporation, Kisarazu, Chiba, Japan) Mice do not vomit. However, they would serve as a less expensive and more convenient species than ferret or dog, which have ability to vomit, for assessing the emetic effect of compounds, if appropriate tests could be developed. With this viewpoint, we evaluated two gastrointestinal function tests in mice, gastrointestinal (GI) transit test and gastric emptying (GE) test, for their ability to predict the emetic effects of 5 well-established compounds. [Method] Male ddY mice were fasted overnight before use. Five percents of charcoal suspension (in 5% gum Arabic solution) was given orally (0.2% mL/mouse), and small intestine was removed at 30 min post-dose to assess GI transient. GE test was carried out as follows: distilled water (0.5 mL) containing 40 resin beads (diameter: 0.6 mm) was given orally, and the number of beads in the stomach at 1 hr post-dose was counted. [Results] CuSO4 enhanced GI transient (10 and 30 mg/kg, p.o.), but inhibited GE (3–30 mg/kg). Cisplatin (C), salmon calcitonin (S) and doxorubicin hydrochloride (D) did not affect GI transient (C:0.3–10 mg/kg, i.v., S: 1–30 units/kg, i.m., D: 0.3–10 mg/kg, i.v.), but inhibited GE (C:1–10 mg/kg, S:3–30 units/kg, D: 3 and 10 mg/kg).
Journal of Pharmacological and Toxicological Methods 58 (2008) 147–178
Respiratory assessment in tethered conscious beagle dogs Philip R. Atterson, K. Kearney, K. Landis, S. Castellucci (WIL Research Laboratories, LLC, Ashland, OH, USA) The assessment of potentially unwanted drug effects on respiratory function are commonly performed in conscious rodents to satisfy the requirements of the ICH S7A guidelines. However, there are certain circumstances whereby the rat may not be a suitable model and an alternative species is required. Models using sling trained conscious beagle dogs have been used for this purpose, although the sling apparatus may have a compromising effect on thoracic movement. This method describes the use of a tethered leash system designed to allow animals to be restrained whilst allowing free thoracic movement. Following acclimation to the restraining apparatus, a neoprene face mask and nylon muzzle are placed over the snout and mouth of the dog. An additional conditioning period is then allowed during which the time of each session can be increased to equate to the projected on-study restraint period. Respiratory activity is then measured by the use of a pneumotach to detect the flow of air in and out of the mask system in response to the animal's thoracic movement. The pneumotach signals are detected by a variable reluctance transducer, amplified and recorded using a suitable data acquisition package. We measured the changes in respiratory frequency (RF), tidal volume (TV) and minute volume (MV) of groups of 4 male beagle dogs following intramuscular administration of either vehicle (0.9% w/v saline) or morphine sulfate at doses of 0.25, 0.5 or 1.0 mg/kg. Data were filtered so that RF N 100 bpm or TV N 500 mL were excluded from the analysis. Respiratory parameters were collected for one hour prior to dosing and continuously for 2 h post dose. Additional 30 min segments were collected around 4 and 6 h post dose. For each parameter, 15-min averages were analyzed. As expected, treatment with morphine resulted in depression of the measured respiratory parameters. This data suggests that the use of the tethered conscious beagle dog is a viable alternative in situations where the rat is not a suitable species for assessment of respiratory function. doi:10.1016/j.vascn.2008.05.113
suggest that both IV boluses were excessive and overloaded animals. 10 mL/kg bolus was compensated by TV increase and did not change MV. In contrast, 20 mL/kg bolus was not completely compensated. More studies are needed to determine the DV that does not affect RP. doi:10.1016/j.vascn.2008.05.114 Refinement of the charcoal meal GI study: Reduction in the fasting period required Helen Prior, L. Ewart, E. Fantham, P. Pimlott, F. Cowell, J.P. Valentin (Safety Assessment UK, AstraZeneca R&D, Alderley Park, Macclesfield, UK) Rodents are routinely fasted overnight (~18 h) prior to charcoal meal GI studies. Prolonged fasting can cause stress, aggression (requiring single-housing), bodyweight loss and more severe clinical signs with test compounds. However, stomachs may be empty after shorter fasts. We investigated whether reduced fasting periods impact on study outcome. Male Han Wistar rats (228–259 g) or CD-1 mice (35–51 g) were fasted for 0, 3, 6 or 18 h prior to dosing (n = 8 per group). Animals were dosed orally with vehicle or atropine (20/30 mg/kg for rats/mice) 1 h prior to a charcoal meal, then killed 15 min later. The % intestinal transit (IT) of charcoal and weight of stomach contents (index of gastric emptying: GE) were measured. Rats fasted for 18 h had a change in bodyweight of − 7%, compared to + 1, + 1 or + 2% after 6, 3 or 0 h fasts respectively. Mice fasted for 18 h had a change in bodyweight of − 14%, compared to − 6, 0 or + 1% after 6, 3 or 0 h fasts respectively. Rats fasted for 18 or 6 h had a group median IT of 59% or 64% and a GE of 1.1 g or 0.6 g (p N 0.05 Mann Whitney test; vehicle) compared to IT of 39% or 36% and GE of 2.5 g or 2.9 g (atropine). Mice fasted for 18 or 6 h had a group median IT of 38% or 45% and a GE of 0.2 g or 0.4 g (p N 0.05; vehicle) compared to IT of 31% or 31% and GE of 0.2 or 0.4 g (atropine). 0 or 3 h fasts led to similar, but more variable data. Charcoal was still clearly visible when food was present in the intestines. In conclusion, fasting rodents for 6 h gives similar results to overnight fasting and has less effect on bodyweight. It also enables group-housing for mice.
Intravenous bolus on rat respiratory study: What is the limit?
doi:10.1016/j.vascn.2008.05.115
Philip R. Atterson, M. Soloviev, K. Kearney, K. Landis, S. Castellucci (WIL Research Laboratories, LLC, Ashland, OH, USA)
Detection of drug-induced emetic effects in mice
Some drug candidates require intravenous (IV) administration. Substantial IV dosing volume (DV) by itself does trigger changes in respiratory parameters (RP). To evaluate RP in response to DV, male rats (9–12 week) were acclimated to the restraint, and studied in the head-out plethysmograph (Buxco Electronics) pre-dose and for 6 h after dosing with saline. The first group was dosed by oral gavage (DV — 10 mL/kg); the second group was dosed subcutaneously (DV — 2 mL/kg); the third group (10bG) was dosed with 10 mL/kg IV bolus over ~2 min; the fourth group (10iG) was dosed by IV infusion (DV — 10 mL/kg over ~30 min); the fifth group (20bG) was dosed with 20 mL/ kg IV bolus over ~ 2 min. Respiratory frequency (RF), tidal volume (TV) and minute volume (MV) were collected using Ponemah Physiology Platform (LDS, Valley View, OH). 15-min averages were analyzed. Immediately after dosing all groups showed an increase in RF by 20–40% compared to baseline; TV and MV was also increased except for 10iG, which were not removed from the plethysmograph for dosing and thus did not demonstrate excessive initial excitement. Within 30–45 min all RP were close to the baseline in all groups, except 10bG (increased TV) and 20bG (RF and MV remained 10–20% higher than at baseline and other groups for at least 4 h). Results
Kentaro Ando, K. Takagi (Mitsubishi Pharma Corporation, Kisarazu, Chiba, Japan) Mice do not vomit. However, they would serve as a less expensive and more convenient species than ferret or dog, which have ability to vomit, for assessing the emetic effect of compounds, if appropriate tests could be developed. With this viewpoint, we evaluated two gastrointestinal function tests in mice, gastrointestinal (GI) transit test and gastric emptying (GE) test, for their ability to predict the emetic effects of 5 well-established compounds. [Method] Male ddY mice were fasted overnight before use. Five percents of charcoal suspension (in 5% gum Arabic solution) was given orally (0.2% mL/mouse), and small intestine was removed at 30 min post-dose to assess GI transient. GE test was carried out as follows: distilled water (0.5 mL) containing 40 resin beads (diameter: 0.6 mm) was given orally, and the number of beads in the stomach at 1 hr post-dose was counted. [Results] CuSO4 enhanced GI transient (10 and 30 mg/kg, p.o.), but inhibited GE (3–30 mg/kg). Cisplatin (C), salmon calcitonin (S) and doxorubicin hydrochloride (D) did not affect GI transient (C:0.3–10 mg/kg, i.v., S: 1–30 units/kg, i.m., D: 0.3–10 mg/kg, i.v.), but inhibited GE (C:1–10 mg/kg, S:3–30 units/kg, D: 3 and 10 mg/kg).