Systemic effects of formoterol and salmeterol: a dose-response comparison in healthy subjects Comparison of combination inhalers vs inhaled corticosteroids alone in moderate persistent asthma. Intracoronary Injections of Salbutamol Demonstrate the Presence of Functional ft-Adrenoceptors in the Human Heart Inhaled corticosteroids, combined with long-acting beta(2)-agonists, improve the perception of bronchoconstriction in asthma. Systemic effects of salbutamol and salmeterol in patients with asthma. Bronchodilator, cardiovascular, and hypokalaemic effects of fenoterol, salbutamol, and terbutaline in asthma Reversing acute bronchoconstriction in asthma: the effect of bronchodilator tolerance after treatment with formoterol. Salmeterol versus formoterol in patients with moderately severe asthma: onset and duration of action. An inhaled glucocorticoid does not prevent tolerance to the bronchoprotective effect of a long-acting inhaled beta 2-agonist. Comparative protective effect of the inhaled beta 2-agonist salbutamol (albuterol) on bronchoconstriction provoked by histamine, methacholine, and adenosine 5'-monophosphate in asthma. Regular inhaled salbutamol and airway responsiveness to allergen Dose-response study of inhaled salmeterol in asthmatic patients with 24-hour spirometry and Holter monitoring. Comparison of the relative efficacy of formoterol and salmeterol in asthmatic patients. Subsensitivity to the bronchodilator action of albuterol produced by chronic administration. Tachyphylaxis to systemic but not to airway responses during prolonged therapy with high dose inhaled salbutamol in asthmatics. The Salmeterol Multicenter Asthma Research Trial: a comparison of usual pharmacotherapy for asthma or usual pharmacotherapy plus salmeterol. Potential masking effects of salmeterol on airway inflammation in asthma. Bronchodilator response to albuterol after regular formoterol and effects of acute corticosteroid administration. Aerosolized terbutaline in asthmatics: development of subsensitivity with long-term administration.
BACKGROUND The main adverse effects of inhaled long acting β2 agonists relate to their systemic activity . The systemic effects seen over eight hours after inhalation of three doses of salmeterol and formoterol were therefore compared in normal subjects . METHODS A double blind , r and omised , crossover study was carried out in 16 healthy subjects who inhaled formoterol 24 , 48 and 96 μg ( via Turbuhaler ® ) , salmeterol 100 , 200 and 400 μg ( via Diskhaler ® ) , or placebo on separate days . Heart rate , systolic and diastolic blood pressure , and plasma potassium and glucose concentrations were measured for eight hours following each drug and mean values were used to plot the time course of change after each dose . Mean maximum ( or minimum ) absolute values were used to construct dose-response curves to calculate the relative dose potency of the two drugs . Lunch was taken after the four hour readings and , since this caused additional changes to the main outcome measures , data from the first four hours are also presented in a post hoc analysis . RESULTS Both salmeterol and formoterol caused an early dose dependent increase in heart rate and glucose concentrations and a fall in diastolic blood pressure and plasma potassium concentration ; formoterol also caused an early increase in systolic blood pressure . The cardiovascular effects occurred more rapidly than the metabolic effects and the response to formoterol was faster than that of salmeterol , apart from the glycaemic response . The effects of salmeterol were slightly more prolonged than those of formoterol , although some dose related effects were apparent at eight hours with both drugs . The relative dose potency for formoterol compared with salmeterol at four and eight hours for the different end points excluding systolic blood pressure ranged from 1.6 to 7.0 after adjusting for baseline values . Relative dose potencies ( 95 % CI ) for maximum heart rate and plasma potassium concentrations were 4.1 ( 3.0 to 5.6 ) and 5.8 ( 4.1 to 8.6 ) over four hours and 2.4 ( 1.2 to 3.8 ) and 3.0 ( 1.2 to 5.7 ) over eight hours . CONCLUSIONS Formoterol and salmeterol cause dose related changes in heart rate , diastolic blood pressure , and plasma glucose and potassium concentrations . Formoterol has a more rapid onset for most end points whereas salmeterol has slightly more prolonged activity . Both drugs have a relatively modest therapeutic window . The relative dose potencies of the two drugs for the main end points were similar to the fourfold difference in recommended doses . Some differences in the pharmacological profile of the two drugs emerged and are as yet unexplained AIMS Inhalers combining long acting beta2-adrenoceptor agonists ( LABA ) and corticosteroids ( ICS ) are indicated at Step 3 of current asthma guidelines . We evaluated the relative effects of LABA + ICS combination vs ICS alone on pulmonary function , bronchoprotection , acute salbutamol recovery following methacholine bronchial challenge , and surrogate inflammatory markers in patients with moderate persistent asthma . METHODS Twenty-nine patients with mean FEV1 ( + /- SEM ) of 78 + /- 3 % predicted completed a r and omized , double-blind , double-dummy , cross-over study . Patients received either 4 weeks of budesonide 400 microg + formoterol 12 microg ( BUD + FM ) combination twice daily followed by 1 week of BUD 400 microg alone twice daily , or 4 weeks of fluticasone propionate 250 microg + salmeterol 50 microg ( FP + SM ) combination twice daily followed by 1 week of FP 250 microg alone twice daily . Measurements were made at baseline and following each r and omized treatment . RESULTS FEV1 increase from pretreatment baseline as mean ( + /- SEM ) % predicted was significantly higher ( P < 0.05 ) for BUD + FM ( 8 + /- 1 % ) vs BUD ( 2 + /- 1 % ) , and for FP + SM ( 8 + /- 1 % ) vs FP ( 2 + /- 1 % ) . The fall in FEV1 following methacholine challenge as percentage change from prechallenge baseline FEV1 was not significantly different in all four groups ; BUD + FM ( 22 + /- 1 % ) , BUD ( 24 + /- 1 % ) , FP + SM ( 23 + /- 1 % ) and FP ( 23 + /- 1 % ) . Salbutamol recovery over 30 min following methacholine challenge as area under curve ( AUC % .min ) was significantly blunted ( P < 0.05 ) with BUD + FM ( 486.7 + /- 35.5 ) vs BUD ( 281.1 + /- 52.8 ) , and with FP + SM ( 553.1 + /- 34.1 ) vs FP ( 368.3 + /- 46.7 ) . There were no significant differences between respective combination inhalers or between respective ICS alone . Decreases in exhaled nitric oxide ( NO ) and serum eosinophilic cationic protein ( ECP ) from baseline were not significantly different between treatments . CONCLUSIONS Combination inhalers improve pulmonary function without potentiating anti-inflammatory effects on exhaled NO and serum ECP as compared with ICS alone , but delay acute salbutamol recovery after bronchoconstriction To demonstrate the presence of functional cardiac β2-adrenoceptors in man , we studied the responses to intracoronary injections of salbutamol in three groups of six patients . We injected salbutamol , a selective β2-adrenoceptor agonist , into the right coronary artery to avoid peripheral vasodilator action and to stimulate the sinoatrial node directly . Salbutamol injections caused a sinus tachycardia . The same doses of salbutamol injected into the aortic root caused no change in heart rate , ruling out a systemic effect . The mean dose required to cause an increase in heart rate of 30 beats/min ( IHR30 ) was 2.6 μg in the first group of six patients . In 12 other patients salbutamol was given after β-blockade to confirm the β2-selectivity of the responses . Doses of practolol ( β1,-selective blockade ) and of propranolol ( β1- and β2-blockade ) that had equal β1-blocking activity were used . In six patients who were given practolol  , the mean IHR30 dose was 2.1 μg . In six patients who were given propranolol , the mean IHR30 dose was significantly greater at 64 μg ( p < 0.001 , practolol vs. propranolol ) . This study demonstrates that direct cardiac β2-adrenoceptor stimulation in man has a positive chronotropic effect The relationship between asthma medication and the perception of asthma symptoms is of interest for daily practice . Poor perception of asthma symptoms might influence patients ' health care behavior and subsequently might lead to undertreatment and deterioration of their disease . This study investigated the influence of the chronic use of short-acting and long-acting beta(2)-agonists , compared with the additional use of inhaled corticosteroids on the perception of histamine-induced bronchoconstriction . Patients with asthma ( 33 male and 31 female , mean age 35 + /- 11 yr , FEV(1 ) 87 + /- 14 % of the reference value , PC(20 ) geometric mean 1.08 mg/ml ( 95 % CI : 0.76 - 1.52 ) were selected and r and omly allocated to the use of either a short-acting beta(2)-agonists ( salbutamol , n = 22 ) or a long-acting beta(2)-agonists ( formoterol , n = 22 ) or placebo ( n = 20 ) , which has been used for 12 wk . This medication treatment was repeated exactly 1 yr later , with patients receiving the same medication plus an inhaled corticosteroid .  Perception of histamine-induced bronchoconstriction was measured at the start of each treatment period and every 4 wk thereafter . Subjects quantified their sensation of respiratory discomfort during the challenge tests on a modified Borg scale . The perceptive " sensitivity " for changes in FEV(1 ) was analyzed by the linear regression slope ( alpha ) " Borg versus percentage fall in FEV(1 ) . " The " absolute perceptual magnitude " was determined by the perception score at the 20 % fall in FEV(1 ) ( PS(20 ) ) . The additional use of inhaled corticosteroids during the second year result ed in an improved perception of histamine-induced bronchoconstriction ( slope alpha ) compared with the first year for only the long-acting beta(2)-agonists group ( p value 0.036 ) . This improvement was not observed for the " absolute perceptual magnitude " ( PS(20 ) ) . The additional use of inhaled corticosteroids during chronic use of long-acting beta(2)-agonists improves the perceptive " sensitivity " for changes in FEV(1 ) during histamine-induced bronchoconstriction , which was not observed for short-acting bronchodilators . This result might indicate that the positive effects on perception of airway obstruction might be another reason ( besides the beneficial effects on the clinical condition ) for prescribing a combination of long-acting beta(2)-agonists and inhaled steroids BACKGROUND --Knowing the extent of the systemic effects of a new beta 2 agonist relative to an established drug is important for the prediction and interpretation of side effects . A recent study in which the effect of cumulative doses of salbutamol was compared with single doses of salmetreol suggested that , weight for weight , salmeterol may be up to 10 times more potent than salbutamol . This current study was design ed to investigate further the dose equivalence of salmeterol and salbutamol . METHODS --Twelve patients with mild asthma inhaled cumulative doses of placebo , salmeterol 25 , 50 , 100 , and 200 micrograms , and salbutamol 100 , 500 , 1000 , and 1000 micrograms on separate days at hourly intervals in a r and omised double blind crossover study . Changes in forced expiratory volume in one second ( FEV1 ) , heart rate , plasma potassium concentration , systolic and diastolic blood pressure were measured . Dose equivalence was determined as the dose ratio of salmeterol to salbutamol for the 50 % maximum response to salbutamol . RESULTS --No important changes occurred in any measurements following placebo . Salmeterol and salbutamol caused a near maximum increase in FEV1 following the first dose so the dose equivalence for the airway effects could not be estimated . Heart rate increased and plasma potassium concentration and diastolic blood pressure decreased in a dose dependent manner following salmeterol and salbutamol , with median dose equivalences for salmeterol compared with salbutamol of 17.7 , 7.8 , and 7.6 , respectively . CONCLUSIONS --These results confirm that the systemic activity of salmeterol compared with salbutamol is higher than would be expected from in vitro data , particularly for heart rate . Whether this is because of the relatively high dose of salmeterol used or pharmacokinetic differences between the two drugs is uncertain The airway response and cardiovascular and hypokalaemic effects of fenoterol , salbutamol , and terbutaline given in multiples of st and ard doses from metered-dose inhalers were studied in ten patients with mild asthma . In a double-blind , crossover , placebo-controlled study the subjects received 2 , 6 , and 18 puffs of each drug with intervals of 90 min , and forced expiratory volume in 1 s , heart rate , QTc interval , plasma potassium concentration , tremor , and bronchial reactivity to histamine were measured . All three drugs produced similar bronchodilatation . However , the rises in heart rate , QTc interval , and tremor and the fall in plasma potassium were greater after fenoterol than after salbutamol or terbutaline . The maximum mean ( SD ) increases in heart rate for fenoterol , salbutamol , and terbutaline were 29 ( 24 ) bpm , 8 ( 9 ) bpm , and 8 ( 14 ) bpm , respectively ; falls in plasma potassium were 0.76 ( 0.62 ) mmol/l , 0.46 ( 0.32 ) mmol/l , and 0.52 ( 0.39 ) mmol/l , respectively . Fenoterol afforded no additional protection against histamine compared with salbutamol . These findings suggest that at doses based on those used in clinical practice fenoterol causes more adverse effects than salbutamol or terbutaline . The most likely explanation for these effects is that fenoterol has been marketed at a higher dose than the other beta 2-agonists ; fenoterol may in addition be less selective for beta 2 receptors Continuous treatment with a short-acting beta2-agonist can lead to reduced bronchodilator responsiveness during acute bronchoconstriction . This study evaluated bronchodilator tolerance to salbutamol following regular treatment with a long-acting beta2-agonist , formoterol . The modifying effect of intravenous corticosteroid was also studied . Ten asthmatic subjects ( using inhaled steroids ) participated in a r and omised , double-blind , placebo-controlled , cross-over study . Formoterol 12 microg b.i.d . or matching placebo was given for 10 - 14 days with > 2 weeks washout . Following each treatment , patients underwent a methacholine challenge to induce a fall in forced expired volume in one second ( FEV1 ) of at least 20 % , then salbutamol 100 microg , 100 microg , and 200 microg was inhaled via a spacer at 5 min intervals , with a further 400 microg at 45 min . After a third single-blind formoterol treatment period , hydrocortisone 200 mg was given intravenously prior to salbutamol . Dose-response curves for change in FEV1 with salbutamol were compared using analysis of covariance to take account of methacholine-induced changes in spirometry . Regular formoterol result ed in a significantly lower FEV1 after salbutamol at each time point compared to placebo ( p<0.01 ) . The area under the curves ( AUCs ) for 15 ( AUC0 - 15 ) and 45 ( AUC0 - 45 ) min were 28.8 % and 29.5 % lower following formoterol treatment ( p<0.001 ) . Pretreatment with hydrocortisone had no significant modifying effect within 2 h of administration . It is concluded that significant tolerance to the bronchodilator effects of inhaled salbutamol occurs 36 h after stopping the regular administration of formoterol . This bronchodilator tolerance is evident in circumstances of acute bronchconstriction We evaluated the profile of the bronchodilatory effect of three inhaled beta2-agonists , 24 microg formoterol , 50 microg salmeterol and 200 microg salbutamol , in patients with stable , moderately severe asthma . Thirty asthmatics ( mean+/-SD age 54+/-8 yrs ; forced expiratory volume in one second ( FEV1 ) 58+/-12 % predicted ; reversibility of FEV1 21+/-8 % from baseline ) participated in a single-centre , double-blind , r and omized , single-dose , cross-over study . FEV1 was obtained in baseline condition and 10 , 20 , 30 , 60 min , and every hour up to 12 h after inhalation of the trial drug . Specific airway conductance ( sGaw ) was measured at baseline condition and 1 , 3 , 5 , 7 , 10 , 20 , 30 , 60 min , and every hour up to 12 h after inhalation . Formoterol produced a mean increase in sGaw ( as % of baseline ) of 44 % after 1 min , maximal ( 135 % ) after 2 h , and 56 % after 12 h. The mean increase in FEV1 was maximal ( 27 % ) after 2h , and 10 % after 12 h. After salmeterol , mean increase in sGaw amounted to 16 % after 3 min , maximal ( 111 % ) after 2 - 4 h , and 58 % after 12 h. The mean increase in FEV1 was maximally 25 % after 3h , being 11 % after 12 h. After salbutamol , mean increase in sGaw was 44 % after 1 min and maximal ( 100 % ) after 30 min . The peak increase in FEV1 was 25 % . We conclude that formoterol ( 24 microg ) and salmeterol ( 50 microg ) had an equal bronchodilatory capacity , which was similar to that of 200 microg salbutamol and lasted for at least 12 h in patients with asthma . However , formoterol had a more rapid onset of action than salmeterol , equal to that of salbutamol There is increasing evidence for the development of tolerance to the protective effects of inhaled beta 2-agonists against bronchoconstrictor stimuli . Animal studies have suggested that glucocorticoids protect against the down-regulation of beta 2-receptors after chronic exposure to beta 2-agonists . In a double-blind placebo-controlled crossover study in 12 patients with mild asthma , we investigated the effect of inhaled budesonide or identical placebo on the protection conferred by albuterol ( 200 micrograms ) against methacholine-induced bronchoconstriction before and after treatment with the long-acting beta 2-agonist salmeterol .  Patients were r and omized to be treated for 3 wk with inhaled budesonide ( 800 micrograms twice a day ) or placebo ; salmeterol ( 50 micrograms twice a day ) was added during the third week . Airway responsiveness to methacholine was measured 15 min after albuterol , both before and exactly 12 h [ corrected ] after the last salmeterol dose . Mean FEV1 increased significantly after 2 wk of budesonide ( p < 0.05 ) and increased further after salmeterol ( p < 0.05 ) compared with placebo . After 2 wk , the bronchoprotective effect of albuterol against methacholine was significantly greater with budesonide than with placebo ( 3.4 versus 2.4 doubling dilutions ; p < 0.05 ) , consistent with an improvement in airway hyperresponsiveness with budesonide therapy . However , regular salmeterol treatment for 1 wk significantly diminished the protection conferred by albuterol against methacholine challenge , both with budesonide and with placebo ( -1.1 + /- 0.42 and -1.41 + /- 0.30 doubling dilutions , respectively ) . There was no significant difference in the loss of bronchoprotection seen with salmeterol between budesonide and placebo treatment periods . Our study suggests that even a high dose of an inhaled glucocorticoid fails to prevent the loss of bronchoprotection produced by regular beta 2-agonist therapy We have investigated the ability of salbutamol to protect against bronchoconstriction induced by methacholine , histamine , and adenosine 5'-monophosphate ( AMP ) in nine subjects with asthma . In a double-blind , placebo-controlled study , salbutamol , 2.5 mg administered by nebulization , increased the geometric mean provocation concentrations of methacholine , histamine , and AMP required to produce a 20 % decrease in FEV1 from 0.3 to 2.2 , 0.4 to 3.8 , and 4.0 to 106.7 mg/ml after placebo and active treatment , respectively ( p less than 0.01 ) . Thus , this dose of beta 2-adrenoceptor agonist displaced the concentration-response curves for methacholine , histamine , and AMP to the right in a parallel fashion by 8.8 ( 0.6 to 29.3)- , 10.3 ( 1.4 to 33)- , and 26.6 ( 1.5 to 76.6)-fold , respectively , the difference between the results for AMP and those for histamine and methacholine being statistically significant ( p less than 0.01 ) . For six of the nine subjects studied , salbutamol displaced the concentration-response curve for AMP to the right by greater than 50-fold . There was no correlation between bronchodilatation and protection against bronchoconstriction induced by any of the agonists . We conclude that salbutamol protects against bronchoconstriction provoked by methacholine and histamine by functional antagonism , whereas with AMP , an additional activity is demonstrable , possibly involving inhibition of mast cell-mediator release Regular inhaled beta 2 agonist causes tolerance to the acute protective effect of beta 2 agonist against bronchoconstriction induced by chemical stimuli such as AMP , histamine , and methacholine . We examined a more clinical ly relevant stimulus , inhaled allergen , in a double-blind , cross-over , r and om-order trial in 13 mild atopic asthmatics , who had not used beta 2 agonist for at least 4 weeks . We compared regular inhaled salbutamol ( 200 micrograms four times daily for 2 weeks ) with placebo ( 2 weeks ) for effects on bronchodilator response , baseline methacholine , and allergen airway responsiveness , and on the acute protective effect of salbutamol against both stimuli . Baseline forced expiratory volume in 1 s ( FEV1 ) , bronchodilator response , and methacholine responsiveness were the same during both treatment periods . After regular salbutamol , the allergen PC20 ( provocation concentration producing a 20 % FEV1 decrease ) fell by 0.91 ( SD 0.66 ) ( p = 0.0009 ) doubling doses , and the protective effects of salbutamol  on methacholine and allergen were both significantly reduced ( p = 0.026 and 0.025 , respectively ) . Taking into account the reduced baseline allergen PC20 , the post-salbutamol allergen PC20 was almost 2 doubling doses ( 1.94 [ 1.43 ] , p < 0.01 ) lower during salbutamol treatment . Thus , 2 weeks of regular inhaled salbutamol increased airway responsiveness to allergen but not to methacholine , and caused tolerance to the protective effect of salbutamol on bronchoconstriction induced by both stimuli . These effects of inhaled beta 2 agonist provide further evidence to support detrimental effects of their regular use Salmeterol is a new long-acting beta 2-selective adrenoceptor agonist . In this double-blind , 6-way crossover study , four single doses of salmeterol by metered dose inhaler ( 12.5 , 25 , 50 , 100 micrograms ) were compared with albuterol aerosol 200 micrograms and placebo in 24 patients with moderate asthma with 24-hour pulmonary function testing and Holter monitoring .  Salmeterol was an effective bronchodilator at each dose evaluated and demonstrated a greater increase in FEV1 above baseline , a slightly slower onset and a longer duration of bronchodilation than albuterol . Median duration s of bronchodilation were 9.0 , 15.6 , 13.4 , and 18.4 hours with increasing doses of salmeterol in comparison to 4.2 hours for albuterol . Holter monitoring showed ( 1 ) a mean maximum heart rate 2 to 5 bpm higher after salmeterol 50 and 100 micrograms compared with placebo and ( 2 ) supraventricular premature beats ( > 30 per hour or > 100 per 24 hours ) more often in the salmeterol 100-micrograms group ( 13 % to 17 % of patients ) than in the placebo ( 4 % ) , albuterol ( 4 % to 8 % ) , or other salmeterol groups ( 4 % to 9 % ) . These differences were not statistically significant . Tremor and palpitations were the most frequently reported drug-related adverse events and their frequencies increased with increasing doses of salmeterol . This study demonstrated that single doses of salmeterol given by metered dose inhaler over an 8-fold range possess substantial , long-lasting bronchodilator activity 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 Evidence of bronchodilator subsensitivity was sought in studies using the specific beta2 adrenergic agonist , albuterol . After a period of 1 or 2 weeks off all oral sympathomimetic agents , the mean response of the patients to the first dose of albuterol was consistently greater than the response after a period during which the drug had been administered regularly . Maximal decrease in response occurred after 2 weeks ' of treatment , and there was no further decrease after prolonged treatment with the same dose of albuterol for periods as long as 1 year High doses of inhaled salbutamol produce substantial improvements in airway response in patients with asthma , and are associated with dose-dependent systemic beta-adrenoceptor responses . The purpose of the present study was to investigate whether tachyphylaxis occurs during prolonged treatment with high dose inhaled salbutamol .  Twelve asthmatic patients ( FEV1 , 81 + /- 4 % predicted ) , requiring only occasional inhaled beta-agonists as their sole therapy , were given a 14-day treatment with high dose inhaled salbutamol ( HDS ) , 4,000 micrograms daily , low dose inhaled salbutamol ( LDS ) , 800 micrograms daily , or placebo ( PI ) by metered-dose inhaler in a double-blind , r and omized crossover design . During the 14-day run-in and during washout periods , inhaled beta-agonists were withheld and ipratropium bromide was substituted for rescue purpose s. At the end of each 14-day treatment , a dose-response curve ( DRC ) was performed , and airway ( FEV1 , FEF25 - 75 ) chronotropic ( HR ) , tremor , and metabolic ( K , Glu ) responses were measured at each step ( from 100 to 4,000 micrograms ) . Treatment had no significant effect on baseline values . There were dose-dependent increases in FEV1 and FEF25 - 75 ( p less than 0.001 ) , and pretreatment with HDS did not displace the DRC to the right . DRC for HR ( p less than 0.001 ) , K ( p less than 0.001 ) , and Glu ( p less than 0.005 ) were attenuated after treatment with HDS compared with PI . There were also differences between HDS and LDS for HR ( p less than 0.001 ) and Glu ( p less than 0.05 ) responses . Frequency and severity of subjective adverse effects were also reduced after HDS : tremor ( p less than 0.001 ) , palpitations ( p less than 0.001 ) . ( ABSTRACT TRUNCATED AT 250 WORDS STUDY OBJECTIVE To compare the safety of salmeterol xinafoate or placebo added to usual asthma care . DESIGN A 28-week , r and omized , double-blind , placebo-controlled , observational study . SETTING Study subjects were seen once in the study physician 's office for screening and were provided all blinded study medication for the entire study period . Follow-up by telephone was scheduled every 4 weeks . PARTICIPANTS Subjects ( > 12 years old ) with asthma as judged by the study physician were eligible . Individuals with a history of long-acting beta2-agonist use were excluded . INTERVENTIONS Salmeterol , 42 mug bid via metered-dose inhaler ( MDI ) , and placebo bid via MDI . MEASUREMENTS AND RESULTS Following an interim analysis in 26,355 subjects , the study was terminated due to findings in African Americans and difficulties in enrollment . The occurrence of the primary outcome , respiratory-related deaths , or life-threatening experiences was low and not significantly different for salmeterol vs placebo ( 50 vs 36 ; relative risk [ RR ] = 1.40 ; 95 % confidence interval [ CI ] , 0.91 to 2.14 ) . There was a small , significant increase in respiratory-related deaths ( 24 vs 11 ; RR , 2.16 ; 95 % CI , 1.06 to 4.41 ) and asthma-related deaths ( 13 vs 3 ; RR , 4.37 ; 95 % CI , 1.25 to 15.34 ) , and in combined asthma-related deaths or life-threatening experiences ( 37 vs 22 ; RR , 1.71 ; 95 % CI , 1.01 to 2.89 ) in subjects receiving salmeterol vs placebo . The imbalance occurred largely in the African-American sub population : respiratory-related deaths or life-threatening experiences ( 20 vs 5 ; RR , 4.10 ; 95 % CI , 1.54 to 10.90 ) and combined asthma-related deaths or life-threatening experiences ( 19 vs 4 ; RR , 4.92 ; 95 % CI , 1.68 to 14.45 ) in subjects receiving salmeterol vs placebo . CONCLUSIONS For the primary end point in the total population , there were no significant differences between treatments . There were small , but statistically significant increases in respiratory-related and asthma-related deaths and combined asthma-related deaths or life-threatening experiences in the total population receiving salmeterol . Subgroup analyses suggest the risk may be greater in African Americans compared with Caucasian subjects . Whether this risk is due to factors including but not limited to a physiologic treatment effect , genetic factors , or patient behaviors leading to poor outcomes remains unknown We hypothesized that regular use of long-acting beta-agonists could delay recognition of ( " mask " ) increasing airway inflammation . We studied steroid-sparing and " masking " effects of salmeterol versus placebo in 13 asthmatic individuals requiring > = 1,500 microgram inhaled corticosteroid daily .  Corticosteroid doses were reduced weekly until criteria were met for an exacerbation or the corticosteroid was fully withdrawn . Subjects were restabilized on their original dose of inhaled corticosteroid for 4 wk before crossover to the alternative treatment . Subjects maintained symptom and peak expiratory flow ( PEF ) diaries , and underwent weekly spirometric , methacholine challenge , sputum eosinophil , and serum eosinophil cationic protein ( ECP ) measurements . Mean corticosteroid dose was reduced by 87 % during salmeterol treatment , versus 69 % with placebo ( p = 0.04 ) . Sputum eosinophils increased before exacerbation despite stable symptoms , FEV1 , and PEF . In the week before clinical exacerbation , sputum eosinophil counts were higher in the salmeterol-treatment arm ( 19.9 + /- 29.8 % [ mean + /- SD ] , versus placebo 9.3 + /- 17.6 % ; p = 0.006 ) . Five subjects showed > 10 % sputum eosinophilia before exacerbation during salmeterol treatment , as compared with two receiving placebo . In this model , salmeterol controlled symptoms and lung function until inflammation became significantly more advanced . We conclude that the bronchodilating and symptom-relieving effects of salmeterol can mask increasing inflammation and delay awareness of worsening asthma BACKGROUND There is controversy about the development of bronchodilator subsensitivity after regular administration of long-acting beta(2)-agonists . OBJECTIVES The purpose of the study was to evaluate whether regular treatment with formoterol affects the bronchodilator response to repeated puffs of albuterol , and also to assess the effects of acute administration of a bolus dose of IV or inhaled corticosteroid . MATERIAL S AND METHODS Twelve patients ( mean [ SD ] age , 43 [ 15 ] years ; FEV(1 ) , 57 [ 17 ] % predicted ) with stable , moderate to severe persistent asthma who were all taking inhaled corticosteroids  were evaluated in a r and omized , placebo-controlled , double-blind , double-dummy , crossover study . Patients received treatments each for 2 weeks followed by a bolus ( IV/inhaled ) of corticosteroid or placebo : ( 1 ) placebo inhaler bid + bolus placebo ; ( 2 ) formoterol Turbuhaler 24 microg metered dosage bid ( delivered dosage 18 microg bid ) + placebo ; ( 3 ) formoterol 24 microg bid + bolus IV hydrocortisone , 200 mg ; or ( 4 ) formoterol 24 microg bid + bolus inhaled budesonide , 1,600 microg .  Bronchodilator response to repeated puffs of albuterol ( 200 to 1,600 microg ) for > 80 min was measured at 2 h after bolus administration of placebo or corticosteroid . The study was powered at the 80 % level to detect a 20 % difference in area under curve between 20 and 80 min ( AUC ) for FEV(1 ) response to albuterol as change from baseline ( primary end point ) . RESULTS There was significant subsensitivity ( p = 0.01 ) of the mean albuterol FEV(1 ) response ( as AUC , L x s ) after formoterol alone ( 737 ) as compared to placebo ( 1,453 ) along with partial reversal by steroid administration : formoterol + hydrocortisone ( 1 , 050 ) , and formoterol + budesonide ( 942 ) . There was a similar pattern of subsensitivity ( p = 0.03 ) for the mean albuterol forced expiratory flow between 25 % and 75 % of vital capacity response ( as AUC , L ) : placebo ( 2,149 ) , formoterol alone ( 1,002 ) , formoterol + hydrocortisone ( 1,402 ) , and formoterol + budesonide ( 1,271 ) . CONCLUSION Regular treatment with formoterol produced significant bronchodilator subsensitivity to repeated puffs of albuterol , which was partially reversed by a bolus dose of systemic or inhaled corticosteroid The peak response and the duration of bronchodilator effect were measured after four inhalations at 20 min intervals of 250 micrograms of aerosolized terbutaline in 13 patients with bronchial asthma . Patients were initially studied after strict avoidance of all adrenergic agents for 2 wk ; they were then studied at 2 wk intervals for 12 wk while receiving 500 micrograms of aerosolized terbutaline q.i.d . The initial testing ( TI ) and the testing at the end of 12 wk ( TII ) were double blind . Both peak response and duration of action decreased significantly between TI and TII . Cumulative dose-response curves showed that further improvement occurred after each inhalation during TI but that there was significant improvement only after the first inhalation during TII
BACKGROUND Epidemiological evidence has suggested a link between beta-agonists and increases in  asthma mortality .
There has been much debate about possible causal links for this association , and whether regular ( daily ) long-acting beta(2)-agonists are safe .
OBJECTIVES The aim of this review is to assess the risk of fatal and non-fatal serious adverse events in trials that r and omised patients with chronic asthma to regular formoterol versus placebo or regular short-acting beta(2)-agonists .