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document
Comparison of the relative efficacy of formoterol and salmeterol in asthmatic patients . Studies performed on airway smooth muscle in vitro have indicated that salmeterol is a partial agonist on the beta2-receptor in comparison to formoterol . In the present study we evaluated whether these pharmacological differences between salmeterol and formoterol also are applicable to asthmatic patients . The protective effects by increasing cumulative doses of formoterol ( 12 , 60 , 120 micrograms ) and salmeterol ( 50 , 250 , 500 micrograms ) on methacholine-induced bronchoconstriction were evaluated in a double-blind , crossover , placebo-controlled design . Patients were regularly treated with salbutamol 200 micrograms twice daily during the study period , to avoid variability in beta2-adrenoceptor tolerance . S-potassium , heart rate corrected Q-T interval ( Q-Tc ) , and tremor score were followed as measures of systemic effects . Formoterol dose-dependently protected against methacholine responsiveness ( 4.6 doubling doses after 120 micrograms ) . Salmeterol , however , showed a flatter dose-response curve , and a significantly weaker maximal protective effect ( 2.8 doubling doses after 250 micrograms ) . Formoterol caused a significantly higher tremor score and a larger drop in S-potassium than salmeterol at the highest doses . These data show that salmeterol is a partial agonist on the beta2-receptor in relation to formoterol in human airways in vivo . Further studies are required to document the clinical consequences of this finding , for example in severe asthmatic patients .
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Intervention_Pharmacological
formoterol
1372
Intervention_Pharmacological
salmeterol
1373
Intervention_Physical
S-potassium , heart rate corrected Q-T interval ( Q-Tc ) , and tremor score were followed as measures of systemic effects
1374
Intervention_Pharmacological
Formoterol
1375
Intervention_Pharmacological
methacholine responsiveness ( 4.6 doubling doses after 120 micrograms )
1376
Outcome_Other
efficacy
1377
Outcome_Other
beta2-adrenoceptor tolerance
1378
Outcome_Other
S-potassium
1379
Outcome_Other
heart rate corrected Q-T interval ( Q-Tc )
1380
Outcome_Other
tremor score
1381
Outcome_Other
tremor score
1382
Outcome_Physical
S-potassium
1383
Participant_Condition
asthmatic
1384
Participant_Condition
asthmatic
1385
Participant_Condition
asthmatic