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A pilot study to evaluate the bronchodilator response pattern to salmeterol in refractory asthma
J ALLERGY CLIN iMMUNOL JANUARY 2002
S244 A b s t r a c t s
42 Predicting Patterns
In Viva Aerosol Delivery Using Simulated Breathing
Andrew P Bosco, Rod Rhem, Myrna B Dolovich Department of Medicine, McMaster University, Hamilton, ON, Canada Mechanical models simulating in viva breathing are often used to evaluate nebulizers. This study investigated whether in vitro measurements of nebulizer performance using simulated tidal breathing (sTB) patterns predicted in viva delivery of a nebulized drug solution. Normal tidal breathing (nTB) patterns of 10 adult mild asthmatics (age 33+-12 yrs, FEV1 90+_9 % pred, Vt 819+-427 ml) were digitally recorded with the Breathe Breath Monitor (Pari GmbH (PG), GER). One representative breath cycle was selected for simulation with the Compas Breath Simulator (CBS; PG). Subjects were then asked to breathe tidally through the mouthpiece of 2 jet nebulizers, the AeroEclipse (AE; Trudell Medical Int, CA) and the LC Star (LCS; PG). Each nebulizer was filled with 3 ml (1.25 rag) of levalbuterol HCI (LEV; Sepracor, USA) and operated with compressed oxygen at 8 lpm. Subjects breathed normally for 1 min (15_+3 bpm), then repeated the manoeuver to nebulizer dryness (n-dry). "Inhaled" aerosol was captured on absolute filters placed between the nebulizer and the mouth. Inspiratory filters, expiratory filters, filter holders, and the residual nebulizer contents were chemically assayed for LEV to determine the distribution of the fill dose (FD). The above was then repeated with the CBS simulating each subject's tidal breathing. Results were compared using the paired t-test. Both nebulizers delivered ~ 30% of the FD in < 10 rain with sTB and nTB. The inhaled dose of LEV collected on the inspiratory filter tended to be less with sTB vs nTB at I min and at n-dry, however only sTB through the LCS significantly underestimated the inhaled dose at n-dry (p=.004). The time to reach n-dry was longer with sTB than nTB, but was significant only for the LCS (p=.004). Comparing the two nebulizers, after 1 min more LEV was delivered by the LCS to the filter than the AE with sTB (p=.030) and nTB (p=.004). With sTB, the dose delivered at n-dry was significantly greater from the AE (p=.013), whereas with nTB, both nebulizers delivered the same dose to the filter at n-dry. However, the time to reach n-dry was more prolonged with the AE than the LCS for both sTB (p=.047) and nTB (p=.003). Breath simulation can adequately mimic subject tidal breathing and thus can estimate in viva aerosol delivery with reasonable accuracy. Improving upon existing simulator limitations (i.e. reproducing only a single breath multiple times, not a series of breaths) could help improve in vitro accuracy.
Outcome (mean:l:SD) Doselnhaledrnin (%FD) Dose Inhaleddry (%FD) Time to n-dry (rain)
743
nTB-AE
sTB-AE
p
5.38_+1.76 4.54_+1.24 .246
nTB-LCS
sTB-LCS
p
6,97-+I.51 5.91_+1.52 .241
30.35-+6.58 28.70+-3.48 .241 29.42_+4.20 23.98_+3.29 .004 6.66+-1.21 7.35_+1.26 .096
5.55-+0.56 6.53_+0.81 .004
Fluticasone Alone and in Combination With Salmeterol Causes a Reduction in the Synthesis of Proteoglycans by Cultured Bronchial Smooth Muscle Cells
Leonard C Altman*, Susan Potter-Perigo§, Gaylene Altman¥, Thomas N Wight§ *University of Washington, Seattle, WA §Vascular Biology Laboratory, Hope Heart Institute, Seattle, WA ~Department of Nursing, University of Washington, Seattle, WA Asthma is characterized by airway wall thickening and obstruction. Part of this thickening is due to airway smooth muscle hyperplasia and hypertrophy and part is due to deposits of connective tissue components in the extracellular matrix between the cells. Fluticasone and salmeterol provide short and long-term control of this disease, however it is uncertain if they alter airway remodeling. To determine if these drugs modify the pathophysiologic changes in the lungs of asthmatics, we examined the effects of these agents on the proliferation and production of proteoglycans by cultured
human airway smooth muscle cells. Cells were cultured in the presence of fluticasone and salmeterol alone and in combination over a concentration range from 1nM to 10laM. Cell proliferation was measured as an increase in fluorometrically detected DNA and proteoglycan synthesis was detected by the incorporation of radio-sulfate into macromolecular material. Fluticasone alone caused a significant decrease in proteoglycan synthesis per cell over a range of concentrations from lnM to 10laM (19-25%), while proliferation was inhibited only at the highest concentration of 10laM. Salmeterol altered proteoglycan synthesis and reduced proliferation only at the 10laM concentration. One laM saimeterol in combination with 10 nM to llaM fluticasone inhibited proliferation of the cells while each of the treatments alone did not. This reduction in proliferation, coupled with the inhibition of synthesis due to fluticasone, resulted in a net reduction in proteoglycan synthesis per well in the cells treated with both reagents in comparison to each reagent alone. The observed inhibition of proteoglycan synthesis by fluticasone occurred at a range of concentrations known to be achieved in viva and may therefore contribute to the inhibition of airway remodeling in asthma.
44 A Pilot Study to Evaluate the Bronchodilatar Response Pattern to Salmeterol in Refractory Asthma
B Guyer, R Gibbs, D Feldsien, Sally Wenzel National Jewish Medical and Research Center, Denver, CO BACKGROUND: In mild to moderate asthmatics, long acting J3-agonists (LABA), such as salmeterol are well known to have a 12-hour or longer duration of action. However, clinical observation suggests that for some severe asthmatics, salmeterol does not appreciably limit the need for supplemental short acting [~-agonists like albuterol. This suggests that the peak and/or the duration of the bronchodilator response to LABA may be decreased in severe asthma. OBJECTIVE: To determine whether the duration of the bronchodilator response to salmeterol and albuterol in a group of severe asthmatics is shorter than the respective 12(+) and 4-6 hour responses predicted from studies of mild-moderate asthmatics. Additionally, to determine if this group has [~2-adrenoreceptor genetic polymorphisms that may explain their response to bronchodilators. METHODS: Nine symptomatic severe (mean baseline FEV 1 55+-3.6%) oral or high dose steroid dependent asthmatics were treated with albuterol 220 lag qid, salmeterol 42 lag bid, or salmeterol 84 lag bid in a randomized double blind, double dummy, crossover design. FEV 1 was measured at baseline and for 8 hours after each treatment at successive time points. Treatment was continued for 1 week and the FEV 1 response was repeated. Only the initial dosing results are reported here. Responses were evaluated by ANOVA with carry forward analysis when subjects dropped from the study before eight hours. RESULTS: The peak bronchodilator response to albuterol was 31+_4.8%. However, by 4 hours the FEVj was no longer statistically different than baseline. The salmeterol (42 lag bid) peak bronchodilator response was 27.7_+5.0%. By 7 hours the FEV l was no longer statistically different than baseline and 5 subjects had dropped from the study because of increased symptoms and declining FEV 1. The salmeterol (84 lag g bid) peak was never statistically different from baseline, although this may have been due to the small sample size. Similar to the low dose salmeterol response, 4 subjects had dropped from the study at 7 hours due to decreasing FEV 1. Individual responses to low and high dose salmeterol appeared to track in 3 patterns: normal to 8 hours (n=3), reduced duration of action (n=4), or reduced peak bronchodilator response (n=2). Genetic analysis showed that 63% of subjects carried a Gly/Gly 16 ~2-adrenoreceptor polymorphism that previous studies have associated with severe asthma. CONCLUSION: In refractory asthmatics the response to salmeterol and albuterol is variable, and generally shorter than expected. The mechanisms involved are unclear, but genetic abnormalities cannot be excluded. Further large scale and mechanistic studies are required. Supported by a grant from GlaxoSmithKline.
S244 A b s t r a c t s
42 Predicting Patterns
In Viva Aerosol Delivery Using Simulated Breathing
Andrew P Bosco, Rod Rhem, Myrna B Dolovich Department of Medicine, McMaster University, Hamilton, ON, Canada Mechanical models simulating in viva breathing are often used to evaluate nebulizers. This study investigated whether in vitro measurements of nebulizer performance using simulated tidal breathing (sTB) patterns predicted in viva delivery of a nebulized drug solution. Normal tidal breathing (nTB) patterns of 10 adult mild asthmatics (age 33+-12 yrs, FEV1 90+_9 % pred, Vt 819+-427 ml) were digitally recorded with the Breathe Breath Monitor (Pari GmbH (PG), GER). One representative breath cycle was selected for simulation with the Compas Breath Simulator (CBS; PG). Subjects were then asked to breathe tidally through the mouthpiece of 2 jet nebulizers, the AeroEclipse (AE; Trudell Medical Int, CA) and the LC Star (LCS; PG). Each nebulizer was filled with 3 ml (1.25 rag) of levalbuterol HCI (LEV; Sepracor, USA) and operated with compressed oxygen at 8 lpm. Subjects breathed normally for 1 min (15_+3 bpm), then repeated the manoeuver to nebulizer dryness (n-dry). "Inhaled" aerosol was captured on absolute filters placed between the nebulizer and the mouth. Inspiratory filters, expiratory filters, filter holders, and the residual nebulizer contents were chemically assayed for LEV to determine the distribution of the fill dose (FD). The above was then repeated with the CBS simulating each subject's tidal breathing. Results were compared using the paired t-test. Both nebulizers delivered ~ 30% of the FD in < 10 rain with sTB and nTB. The inhaled dose of LEV collected on the inspiratory filter tended to be less with sTB vs nTB at I min and at n-dry, however only sTB through the LCS significantly underestimated the inhaled dose at n-dry (p=.004). The time to reach n-dry was longer with sTB than nTB, but was significant only for the LCS (p=.004). Comparing the two nebulizers, after 1 min more LEV was delivered by the LCS to the filter than the AE with sTB (p=.030) and nTB (p=.004). With sTB, the dose delivered at n-dry was significantly greater from the AE (p=.013), whereas with nTB, both nebulizers delivered the same dose to the filter at n-dry. However, the time to reach n-dry was more prolonged with the AE than the LCS for both sTB (p=.047) and nTB (p=.003). Breath simulation can adequately mimic subject tidal breathing and thus can estimate in viva aerosol delivery with reasonable accuracy. Improving upon existing simulator limitations (i.e. reproducing only a single breath multiple times, not a series of breaths) could help improve in vitro accuracy.
Outcome (mean:l:SD) Doselnhaledrnin (%FD) Dose Inhaleddry (%FD) Time to n-dry (rain)
743
nTB-AE
sTB-AE
p
5.38_+1.76 4.54_+1.24 .246
nTB-LCS
sTB-LCS
p
6,97-+I.51 5.91_+1.52 .241
30.35-+6.58 28.70+-3.48 .241 29.42_+4.20 23.98_+3.29 .004 6.66+-1.21 7.35_+1.26 .096
5.55-+0.56 6.53_+0.81 .004
Fluticasone Alone and in Combination With Salmeterol Causes a Reduction in the Synthesis of Proteoglycans by Cultured Bronchial Smooth Muscle Cells
Leonard C Altman*, Susan Potter-Perigo§, Gaylene Altman¥, Thomas N Wight§ *University of Washington, Seattle, WA §Vascular Biology Laboratory, Hope Heart Institute, Seattle, WA ~Department of Nursing, University of Washington, Seattle, WA Asthma is characterized by airway wall thickening and obstruction. Part of this thickening is due to airway smooth muscle hyperplasia and hypertrophy and part is due to deposits of connective tissue components in the extracellular matrix between the cells. Fluticasone and salmeterol provide short and long-term control of this disease, however it is uncertain if they alter airway remodeling. To determine if these drugs modify the pathophysiologic changes in the lungs of asthmatics, we examined the effects of these agents on the proliferation and production of proteoglycans by cultured
human airway smooth muscle cells. Cells were cultured in the presence of fluticasone and salmeterol alone and in combination over a concentration range from 1nM to 10laM. Cell proliferation was measured as an increase in fluorometrically detected DNA and proteoglycan synthesis was detected by the incorporation of radio-sulfate into macromolecular material. Fluticasone alone caused a significant decrease in proteoglycan synthesis per cell over a range of concentrations from lnM to 10laM (19-25%), while proliferation was inhibited only at the highest concentration of 10laM. Salmeterol altered proteoglycan synthesis and reduced proliferation only at the 10laM concentration. One laM saimeterol in combination with 10 nM to llaM fluticasone inhibited proliferation of the cells while each of the treatments alone did not. This reduction in proliferation, coupled with the inhibition of synthesis due to fluticasone, resulted in a net reduction in proteoglycan synthesis per well in the cells treated with both reagents in comparison to each reagent alone. The observed inhibition of proteoglycan synthesis by fluticasone occurred at a range of concentrations known to be achieved in viva and may therefore contribute to the inhibition of airway remodeling in asthma.
44 A Pilot Study to Evaluate the Bronchodilatar Response Pattern to Salmeterol in Refractory Asthma
B Guyer, R Gibbs, D Feldsien, Sally Wenzel National Jewish Medical and Research Center, Denver, CO BACKGROUND: In mild to moderate asthmatics, long acting J3-agonists (LABA), such as salmeterol are well known to have a 12-hour or longer duration of action. However, clinical observation suggests that for some severe asthmatics, salmeterol does not appreciably limit the need for supplemental short acting [~-agonists like albuterol. This suggests that the peak and/or the duration of the bronchodilator response to LABA may be decreased in severe asthma. OBJECTIVE: To determine whether the duration of the bronchodilator response to salmeterol and albuterol in a group of severe asthmatics is shorter than the respective 12(+) and 4-6 hour responses predicted from studies of mild-moderate asthmatics. Additionally, to determine if this group has [~2-adrenoreceptor genetic polymorphisms that may explain their response to bronchodilators. METHODS: Nine symptomatic severe (mean baseline FEV 1 55+-3.6%) oral or high dose steroid dependent asthmatics were treated with albuterol 220 lag qid, salmeterol 42 lag bid, or salmeterol 84 lag bid in a randomized double blind, double dummy, crossover design. FEV 1 was measured at baseline and for 8 hours after each treatment at successive time points. Treatment was continued for 1 week and the FEV 1 response was repeated. Only the initial dosing results are reported here. Responses were evaluated by ANOVA with carry forward analysis when subjects dropped from the study before eight hours. RESULTS: The peak bronchodilator response to albuterol was 31+_4.8%. However, by 4 hours the FEVj was no longer statistically different than baseline. The salmeterol (42 lag bid) peak bronchodilator response was 27.7_+5.0%. By 7 hours the FEV l was no longer statistically different than baseline and 5 subjects had dropped from the study because of increased symptoms and declining FEV 1. The salmeterol (84 lag g bid) peak was never statistically different from baseline, although this may have been due to the small sample size. Similar to the low dose salmeterol response, 4 subjects had dropped from the study at 7 hours due to decreasing FEV 1. Individual responses to low and high dose salmeterol appeared to track in 3 patterns: normal to 8 hours (n=3), reduced duration of action (n=4), or reduced peak bronchodilator response (n=2). Genetic analysis showed that 63% of subjects carried a Gly/Gly 16 ~2-adrenoreceptor polymorphism that previous studies have associated with severe asthma. CONCLUSION: In refractory asthmatics the response to salmeterol and albuterol is variable, and generally shorter than expected. The mechanisms involved are unclear, but genetic abnormalities cannot be excluded. Further large scale and mechanistic studies are required. Supported by a grant from GlaxoSmithKline.