Adverse reactions to beta 2-agonist bronchodilators

Discovery, Multiparametric Optimization, and Solid-State Driven Identification of CHF-6550, a Novel Soft Dual Pharmacology Muscarinic Antagonist and β2 Agonist (MABA) for the Inhaled Treatment of Respiratory Diseases

Clinical guidelines for COPD and asthma recommend inhaled β-adrenergic agonists, muscarinic antagonists, and, for frequent exacerbators, inhaled corticosteroids, with the challenge of combining them into a single device. The MABA (muscarinic antagonist and β2 agonist) concept has the potential to simplify this complexity while increasing the efficacy of both pharmacologies. In this article, we report the outcome of our solid-state driven back-up program that led to the discovery of the MABA compound CHF-6550. A soft drug approach was applied, aiming at high plasma protein binding and high hepatic clearance, concurrently with an early stage assessment of crystallinity through a dedicated experimental workflow. A new chemotype was identified, the diphenyl hydroxyacetic esters, able to generate crystalline material. Among this class, CHF-6550 demonstrated in vivo efficacy, suitability for dry powder inhaler development, favorable pharmacokinetics, and safety in preclinical settings and was selected as a back-up candidate, fulfilling the desired pharmacological and solid-state profile.

Effect of twice daily inhaled albuterol on cardiopulmonary exercise outcomes, dynamic hyperinflation, and symptoms in secondhand tobacco-exposed persons with preserved spirometry and air trapping: a randomized controlled trial

BACKGROUND

In tobacco-exposed persons with preserved spirometry (active smoking or secondhand smoke [SHS] exposure), air trapping can identify a subset with worse symptoms and exercise capacity. The physiologic nature of air trapping in the absence of spirometric airflow obstruction remains unclear. The aim of this study was to examine the underlying pathophysiology of air trapping in the context of preserved spirometry and to determine the utility of bronchodilators in SHS tobacco-exposed persons with preserved spirometry and air trapping.

METHODS

We performed a double-blinded placebo-controlled crossover randomized clinical trial in nonsmoking individuals at risk for COPD due to exposure to occupational SHS who had preserved spirometry and air trapping defined as either a residual volume-to-total lung capacity ratio (RV/TLC) > 0.35 or presence of expiratory flow limitation (EFL, overlap of tidal breathing on maximum expiratory flow-volume loop) on spirometry at rest or during cardiopulmonary exercise testing (CPET). Those with asthma or obesity were excluded. Participants underwent CPET at baseline and after 4-week trials of twice daily inhalation of 180 mcg of albuterol or placebo separated by a 2-week washout period. The primary outcome was peak oxygen consumption (VO2) on CPET. Data was analyzed by both intention-to-treat and per-protocol based on adherence to treatment prescribed.

RESULTS

Overall, 42 participants completed the entire study (66 ± 8 years old, 91% female; forced expiratory volume in 1 s [FEV1] = 103 ± 16% predicted; FEV1 to forced vital capacity [FVC] ratio = 0.75 ± 0.05; RV/TLC = 0.39 ± 0.07; 85.7% with EFL). Adherence was high with 87% and 93% of prescribed doses taken in the treatment and placebo arms of the study, respectively (P = 0.349 for comparison between the two arms). There was no significant improvement in the primary or secondary outcomes by intention-to-treat or per-protocol analysis. In per-protocol subgroup analysis of those with RV/TLC > 0.35 and ≥ 90% adherence (n = 27), albuterol caused an improvement in peak VO2 (parameter estimate [95% confidence interval] = 0.108 [0.014, 0.202]; P = 0.037), tidal volume, minute ventilation, dynamic hyperinflation, and oxygen-pulse (all P < 0.05), but no change in symptoms or physical activity.

CONCLUSIONS

Albuterol may improve exercise capacity in the subgroup of SHS tobacco-exposed persons with preserved spirometry and substantial air trapping. These findings suggest that air trapping in pre-COPD may be related to small airway disease that is not considered significant by spirometric indices of airflow obstruction.

Pharmacokinetics of extrafine beclometasone dipropionate/formoterol fumarate/glycopyrronium bromide in adolescent and adult patients with asthma

The single-inhaler extrafine formulation triple combination beclometasone dipropionate (BDP), formoterol fumarate (FF) plus glycopyrronium bromide (GB) is available for asthma management in adults. Its use in adolescents has not yet been evaluated. This study investigated the pharmacokinetic profile of BDP/FF/GB in adults and adolescents, with the aim of ruling out higher plasma exposure in adolescents compared to adults. In this open-label, non-randomized study, patients with asthma aged 12-17 (adolescents) and 18-64 years (adults) self-administered a single dose of BDP/FF/GB 400/24/50 μg via pressurized metered-dose inhaler (pMDI). The primary objective was to rule out higher systemic exposure to beclometasone 17-monopropionate (B17MP; active metabolite of BDP), formoterol, and GB in terms of the area under the plasma concentration-time curve from 0 to the last quantifiable concentration (AUC0-t ) in adolescents versus adults. A total of 40 adolescents and 40 adults entered the study (mean age of 14.8 and 43.6 years, respectively). The primary objective (AUC0-t ) was met, with the upper 90% confidence interval of the geometric mean ratio between adolescents and adults <125% for B17MP (point estimate 79.28 [90% CI 71.19; 88.29]), formoterol (88.68 [77.71; 101.20]) and GB (85.49 [72.96; 100.16]). All secondary pharmacokinetic endpoints supported the primary, with pharmacodynamic (safety) and tolerability results similar in the two populations. In conclusion, systemic exposure to extrafine BDP/FF/GB pMDI in adolescents was not higher than that in adults. Furthermore, there were no safety or tolerability signals to warrant a reduction in the dose of BDP/FF/GB for adolescents with asthma.

Association between Inhaled β2-agonists Initiation and Risk of Major Adverse Cardiovascular Events: A Population-based Nested Case-Control Study

Purpose

Despite ample evidence underpinning the efficacy of β₂-agonists in asthma and chronic obstructive pulmonary disease (COPD), the occurrence of β₁- and β₂-adrenoceptors in the heart suggests that β₂-agonists may have deleterious cardiac effects. We investigated the association between new users of long-or short-acting β₂-agonists (LABA or SABA) or ICS (inhaled corticosteroids)/LABA and major adverse cardiovascular events (MACE).

Methods

A nested case–control analysis was conducted using the UK Clinical Practice Research Datalink of patients with asthma, COPD or asthma–COPD overlap with initial treatment of LABA, SABA, ICS/LABA, ICS, long-or short-acting muscarinic antagonist (LAMA or SAMA) between 01 January 1998 and 31 July 2018. The primary outcome was MACE, defined as the first occurrence of stroke, heart failure, myocardial infarction, arrhythmia, or cardiovascular death. Each case was matched with up to 10 controls on age, sex, date of cohort-entry, and duration of follow-up. The risk of MACE associated with β₂-agonists was estimated using conditional logistic regression after controlling for potential confounders.

Results

The cohort included 180,567 new users of β₂-agonists, ICS, SAMA, or LAMA. Among asthmatics, β₂-agonists were not associated with the risk of MACE (SABA vs ICS: HR 1.29 [0.96–1.73]; ICS/LABA vs ICS, HR 0.75 [0.33–1.73]). In contrast, among COPD patients, LABA (HR, 2.38 [1.04–5.47]), SABA (HR, 2.02 [1.13–3.59]) and ICS/LABA (HR, 2.08 [1.04–4.16]) users had an increased risk of MACE compared with SAMA users. Among patients with asthma–COPD overlap, SABA (HR, 2.57 [1.26–5.24]) was associated with an increased risk of MACE compared with ICS.

Conclusion

In conclusion, initiation of LABA, SABA, or ICS/LABA in COPD or SABA in asthma–COPD overlap is associated with increased risk of MACE. No associations were observed among patients with asthma.

Salbutamol-Induced QT Interval Prolongation in a Two-Year-Old Patient

Salbutamol-induced QT interval prolongation is a relatively rare adverse effect of beta2-agonists. We report a case of a two-year-old female patient with no known past medical history, brought by her parents to the ED 30 minutes after ingesting a total dose of 97 mg of salbutamol solution. ECG was done for the patient when she arrived and showed sinus tachycardia with prolonged QTc (509 ms) and normal QRS complex. The patient was admitted to the Pediatric Intensive Care Unit (PICU) with persistent tachycardia and tachypnea in the initial reassessment. ECG was repeated with normal QT interval after IV Mg sulfate. The patient was observed in PICU for 12 hours with serial ECG and venous blood gas (VBG). IV potassium chloride (KCL) infusion started, and serial VBG showed normal potassium and lactate. The patient was doing well in the next six hours, with normal serial ECG, labs, and vital signs.

In conclusion, salbutamol-induced QT prolongation has infrequently been reported in the literature. Although inhaled salbutamol is commonly used in clinical practice, physicians have limited experience with the severe features of its toxicity. Salbutamol is known to cause minimal side effects, which may be under-recognized and progress to serious manifestations such as hypokalemia, QT prolongation, and sudden cardiac death.

Ethnic Sensitivity Study of the Extrafine, Single-Inhaler, Triple Therapy Beclomethasone Dipropionate, Formoterol Fumarate, and Glycopyrronium Bromide Pressurized Metered Dose Inhaler in Japanese and Caucasian Healthy Individuals: A Randomized, Double-Blind, Single-Dose Crossover Study

PURPOSE

A number of single-inhaler, fixed-dose, triple combinations are available for the management of chronic obstructive pulmonary disease and/or asthma. One of these is the extrafine formulation beclomethasone dipropionate, formoterol fumarate, glycopyrronium bromide (BDP/FF/GB). Given that differences in ethnicity can result in differences in systemic exposure, we evaluated the relative pharmacokinetic (PK) profiles of BDP/FF/GB in Japanese vs Caucasian healthy volunteers to assess the need for dose adjustment.

METHODS

This randomized, double-blind, single-dose, 4-way crossover study recruited healthy men and women 20 to 55 years of age; for each Japanese person a Caucasian was enrolled who matched in terms of sex, age, and weight. Study treatments included BDP/FF/GB 200/12/25 and 400/12/25 μg (therapeutic), 800/48/100 μg (supratherapeutic), and placebo. PK blood samples were taken up to 24 hours for evaluation of BDP, beclomethasone 17-monopropionate (B17MP, an active metabolite of BDP), and formoterol and up to 48 h for GB. The primary objective was to characterize the PK profiles of BDP, FF, and GB after administration of a single dose of BDP/FF/GB in Caucasian and Japanese healthy volunteers in terms of the AUC_0-t and C_max of B17MP, formoterol, and GB.

FINDINGS

Of the 32 recruited participants (16 Japanese and 16 Caucasian ), 30 completed the study. A clear plasma exposure dose-response relationship was found for all 4 molecules. B17MP C_max geometric mean ratios for Japanese vs Caucasian participants for the 3 study treatments ranged from 1.17 to 1.26, and AUC_0-t ratios ranged from 1.16 to 1.22; thus, the findings were comparable between the ethnicities. Formoterol exposure was higher in Japanese than Caucasian participants (C_max, 1.22-1.53; AUC_0-t, 1.23-1.40). The GB C_max with BDP/FF/GB 400/12/25 μg (1.09) and AUC_0-t values for all three doses (0.98-1.17) were comparable in the 2 populations, but C_max with 200/12/25 and 800/48/100 μg were higher in Japanese participants (1.32 and 1.42, respectively). Pharmacodynamic (cortisol, potassium, glucose, blood pressure, heart rate, and QT interval with the Fridericia correction) and safety profile results were similar in the 2 ethnicities, with most patients not experiencing any adverse events.

IMPLICATIONS

Exposure to BDP/FF/GB pressurized metered dose inhaler at therapeutic and supratherapeutic doses was associated with higher plasma levels in Japanese versus Caucasian healthy volunteers. These PK differences did not translate into meaningful differences in the safety or pharmacodynamic parameters assessed in this study and were consistent with the results of other long-term (52-week) published studies. Dose adjustments in Japanese people are not deemed necessary. CLINICALTRIALS.

GOV IDENTIFIER

NCT03859414.

Salbutamol Abuse is Associated with Ventricular Fibrillation

Salbutamol-induced cardiac complications are well-established. Herein, we describe a case of a 24-year female who was admitted to the emergency department because of a suicide attempt with salbutamol (76 mg). Salbutamol abuse induced the development of supraventricular tachycardia and ventricular fibrillation. Regular sinus rhythm was restored with defibrillation. The hypokalemic patient who stayed in the intensive care unit was discharged after 48 hours of hospitalization.

Micronucleus induction in the bone marrow of rats by pharmacological mechanisms. II: long-acting beta-2 agonism

AZD9708 is a new chemical entity with selective and long-acting β2-agonistic properties currently being evaluated by AstraZeneca for potential use in treatment of respiratory diseases by the inhaled route. As part of the toxicological characterisation of this compound, an increased incidence of micronucleated immature erythrocytes (MIEs) was seen in the bone marrow of rats following single intravenous doses near the maximum tolerated. This effect was seen in the absence of in vitro genotoxicity in bacterial and mammalian cells and no consistent evidence of in vivo DNA damage in the the bone marrow or liver using the comet assay was observed. Because of the lack of signals for mutagenic potential, combined with the observation that MIE frequencies appeared to be increased in only some of the rats and the clearest response was seen at the intermediate dose, it was hypothesised that the effect was secondary to β2-adrenergic receptor overstimulation. Because it appears that this has not been previously described for β2-agonists and because pharmacodynamic/pharmacokinetic factors may influence the response, studies using repeated dosing were performed to investigate whether this would lead to compound-induced tachyphylaxis with tolerance induction and decreased responses indicated by β2-effect biomarkers. A series of experiments confirmed that a sequence of five escalating daily doses leading to systemic exposure corresponding to that after a single dose led to symptomatic tolerance, declining or diminished effects on plasma biomarkers of β2-effects (plasma glucose and potassium) and elimination of the micronucleus response. This suggests that the increased MIE frequencies after single doses of AZD9708 are secondary to physiological overstimulation of β2-adrenergic receptors, not a consequence of genotoxicity.

Safety of indacaterol in the treatment of patients with COPD

Purpose

Pooled data were analyzed to evaluate the safety and tolerability of indacaterol, a once-daily inhaled long-acting β₂-agonist for chronic obstructive pulmonary disease (COPD).

Patients and methods

Data were pooled from clinical studies of 3–12 months’ duration in patients with moderate-to-severe COPD receiving double-blind indacaterol 75 μg (n = 449), 150 μg (n = 2611), 300 μg (n = 1157), or 600 μg once daily (n = 547); formoterol 12 μg twice daily (n = 556); salmeterol 50 μg twice daily (n = 895); placebo (n = 2012); or tiotropium 18 μg once daily, given open label or blinded (n = 1214). Outcomes were adverse events, serious adverse events and deaths, plasma potassium, blood glucose, and QTc interval and vital signs.

Results

The commonest adverse events with indacaterol were COPD worsening, nasopharyngitis, and headache; most cases were mild or moderate and incidence was generally similar to placebo and other active treatments. The risk of acute respiratory serious adverse events (leading to hospitalization, intubation, or death) was not significantly increased with any of the active treatments compared with placebo. COPD exacerbation rates (analyzed in the intent-to-treat population) were significantly reduced with all active treatments versus placebo. Hazard ratios versus placebo for major cardiovascular adverse events were <1 for all indacaterol doses. Notable values for vital signs and measures of systemic β₂-adrenoceptor activity were rare with indacaterol. The number of deaths adjusted per patient-year was lower with indacaterol (all doses combined) than with placebo (relative risk 0.21 [95% confidence interval 0.07–0.660], P = 0.008).

Conclusion

Indacaterol has a good profile of safety and tolerability that is appropriate for the maintenance treatment of patients with COPD.

Bronchodilator efficacy of single doses of indacaterol in Japanese patients with COPD: A randomised, double-blind, placebo-controlled trial

BACKGROUND

Indacaterol is an investigational, novel, inhaled once-daily ultra-long-acting beta-2 agonist for the treatment of chronic obstructive pulmonary disease (COPD). This study evaluated the 24-h bronchodilatory efficacy and safety of indacaterol in Japanese patients with COPD.

METHODS

This Phase-II, randomised, placebo-controlled, crossover study comprised four double-blind, single-dose treatment periods (washout between periods: 14-28 days). Japanese patients aged 40-75 years with moderate-to-severe COPD were randomised to receive single doses of indacaterol (150, 300, or 600 microg) or placebo via a single-dose dry-powder inhaler. Efficacy (primary endpoint: standardised FEV(1)AUC(22-24h)) and safety were assessed for 24 h post-dose in each treatment period.

RESULTS

Of the 50 patients randomised (92% male; mean age, 67.2 years), 45 completed the study. Standardised FEV(1)AUC(22-24h) was significantly higher for all indacaterol doses as compared with placebo, with clinically relevant differences of 130, 160, and 170 mL for 150, 300, and 600 microg, respectively (P < 0.001). The improvement in FEV(1) was seen as early as 5 min post-dose with indacaterol and sustained for 24 h (P < 0.001 vs placebo at all time points). All indacaterol doses were well tolerated and showed no clinically meaningful effect on pulse rate, blood pressure, QTc interval, and laboratory parameters when compared with placebo.

CONCLUSIONS

In the Japanese COPD population studied, single doses of indacaterol (150, 300, and 600 microg) provided sustained 24-h bronchodilation, with onset of action within 5 min post-dose. All doses were well tolerated. These results are consistent with data from Caucasian populations.

A dose-ranging study of indacaterol in obstructive airways disease, with a tiotropium comparison

This dose-ranging study assessed the bronchodilator efficacy and tolerability of indacaterol, a novel once-daily inhaled beta2-agonist, in subjects clinically diagnosed with COPD. Comparative data with tiotropium were collected. In the double-blind, core period of the study, 635 subjects with COPD (prebronchodilator FEV(1)40% of predicted and > or =1.0L; FEV1/FVC <70%) were randomized to receive indacaterol 50, 100, 200 or 400microg or placebo via multi-dose dry powder inhaler, or indacaterol 400microg via single-dose dry powder inhaler, once daily for 7 days. After completing double-blind treatment and washout, a subset of subjects from each treatment group entered an open-label extension and received tiotropium 18microg once daily for 8 days. The primary efficacy variable was the trough bronchodilator effect: standardized area under the FEV1 curve between 22 and 24h post-dose (FEV1 AUC(22-24h)) on Day 1. Clinically relevant improvements versus placebo in FEV1 AUC(22-24h) were seen for 400 and 200microg doses on Day 1 and all doses on Day 7. All indacaterol doses significantly (P<0.05) increased FEV1 from 5min to 24h post-dose; the 400 and 200microg doses were most effective. All doses were well tolerated. Indacaterol trough FEV1 levels compared favorably with the improvement seen by Day 8 in subjects treated with tiotropium in the open-label extension. The results confirm that indacaterol has a 24-h duration of bronchodilator effect and a fast onset of action in COPD and suggest that indacaterol could be an effective once-daily inhaled beta2-agonist bronchodilator. Indacaterol demonstrated a good overall safety and tolerability profile.

Single inhaler budesonide/formoterol in exacerbations of chronic obstructive pulmonary disease

Inhaled bronchodilators, particularly short-acting inhaled beta(2)-agonists, and systemic glucocorticosteroids are effective treatments for acute exacerbations of chronic obstructive pulmonary disease (COPD). However, in the treatment of these episodes there may be some advantages to the longer-acting agents in that there will be prolonged bronchodilation. Moreover, high doses of systemic glucocorticosteroids are associated with a significant risk of side effects. In the last few years, evidence is mounting that nebulized budesonide and inhaled formoterol might be an alternative to oral prednisolone and short-acting beta(2)-agonists, respectively, in the treatment of acute exacerbations of COPD. Interestingly, some new data suggest that a combination therapy with single inhaler containing budesonide and formoterol may be an alternative to traditional therapy in the treatment of acute exacerbations of this disorder. However, since individual studies are typically statistically underpowered and are remarkably heterogeneous with regard to their conclusions, larger studies are needed to confirm these preliminary findings and determine conclusively any impact of budesonide/formoterol combination in acutely ill COPD patients.

Cardiovascular safety of beta(2)-adrenoceptor agonist use in patients with obstructive airway disease: a systematic review

BACKGROUND

beta(2)-Adrenoceptor agonists have been used as bronchodilators in the management of asthma and chronic obstructive pulmonary disease (COPD); however, there is evidence suggesting that beta(2)-adrenoceptor agonist use may increase morbidity and mortality.

METHODS

A systematic review of case-control studies and randomised controlled trials was performed to evaluate the cardiovascular safety of beta(2)-adrenoceptor agonist use in patients with obstructive airway disease, defined as asthma or COPD.

RESULTS

Case-control studies have shown that beta(2)-adrenoceptor agonist use is associated with an increased risk of myocardial infarction, congestive heart failure, cardiac arrest and sudden cardiac death. The degree of risk appears to be dose-dependent, and may be highest for new users and those with concomitant cardiac conditions. Pooled data from randomised placebo-controlled trials indicate that beta(2)-adrenoceptor agonist use increases the risk of adverse cardiovascular events by more than 2-fold compared with placebo, thus providing evidence that the association seen in case-control studies is a causal one. Single doses of beta(2)-adrenoceptor agonists significantly increase heart rate and decrease potassium concentrations compared with placebo.

CONCLUSIONS

Initiation of beta(2)-adrenoceptor agonist treatment increases heart rate and decreases potassium concentrations, while continued use may increase the risk of adverse cardiovascular events. It could be through these effects of beta-adrenergic stimulation that beta(2)-adrenoceptor agonists may induce ischaemia, congestive heart failure, arrhythmias and sudden cardiac death. In addition to increasing adverse cardiovascular events, beta(2)-adrenoceptor agonist use may induce respiratory tolerance and increase the risk of asthma attacks. It is not clear whether beta(2)-adrenoceptor agonists should be used regularly in the treatment of obstructive airway disease, with or without concomitant cardiovascular disease.

Hypoglycemia after albuterol overdose in a pediatric patient

Albuterol overdose can lead to tachycardia, hypotension, tremor, hypokalemia, and hyperglycemia in children. Hypoglycemia had been previously reported in only one child. We describe a 3-year-old boy who ingested high-dose albuterol in this report. On arrival to the emergency department, the child was agitated and had noticeable restlessness, sinus tachycardia, mild hypokalemia (3.2 mEq/L), and hyperglycemia (187 mg/dL). Activated charcoal and intravenous hydration were given, and electrocardiogram monitoring was performed. Sinus tachycardia resolved within 4 to 6 hours. Hypoglycemia (45 mg/dL) was identified 4 hours after admission. The child recovered uneventfully within 24 hours with glucose replacement. This case suggests that hypoglycemia could be a late complication of acute albuterol overdose; thus, the period of observation should be extended in these cases.

Cardiovascular Effects of β-Agonists in Patients With Asthma and COPD

BACKGROUND

beta-Adrenergic agonists exert physiologic effects that are the opposite of those of beta-blockers. beta-Blockers are known to reduce morbidity and mortality in patients with cardiac disease. beta(2)-Agonist use in patients with obstructive airway disease has been associated with an increased risk for myocardial infarction, congestive heart failure, cardiac arrest, and acute cardiac death.

OBJECTIVES

To assess the cardiovascular safety of beta(2)-agonist use in patients with obstructive airway disease, defined as asthma or COPD.

METHODS

A meta-analysis of randomized placebo-controlled trials of beta(2)-agonist treatment in patients with obstructive airway disease was performed, to evaluate the short-term effect on heart rate and potassium concentrations, and the long-term effect on adverse cardiovascular events. Longer duration trials were included in the analysis if they reported at least one adverse event. Adverse events included sinus and ventricular tachycardia, syncope, atrial fibrillation, congestive heart failure, myocardial infarction, cardiac arrest, or sudden death.

RESULTS

Thirteen single-dose trials and 20 longer duration trials were included in the study. A single dose of beta(2)-agonist increased the heart rate by 9.12 beats/min (95% confidence interval [CI], 5.32 to 12.92) and reduced the potassium concentration by 0.36 mmol/L (95% CI, 0.18 to 0.54), compared to placebo. For trials lasting from 3 days to 1 year, beta(2)-agonist treatment significantly increased the risk for a cardiovascular event (relative risk [RR], 2.54; 95% CI, 1.59 to 4.05) compared to placebo. The RR for sinus tachycardia alone was 3.06 (95% CI, 1.70 to 5.50), and for all other events it was 1.66 (95% CI, 0.76 to 3.6).

CONCLUSION

beta(2)-Agonist use in patients with obstructive airway disease increases the risk for adverse cardiovascular events. The initiation of treatment increases heart rate and reduces potassium concentrations compared to placebo. It could be through these mechanisms, and other effects of beta-adrenergic stimulation, that beta(2)-agonists may precipitate ischemia, congestive heart failure, arrhythmias, and sudden death.

Acute effects of higher than customary doses of salmeterol and salbutamol in patients with acute exacerbation of COPD

Worsening of underlying bronchospasm may be associated with acute exacerbations of chronic obstructive pulmonary disease (COPD). As airway obstruction becomes more severe, the therapeutic option is to add salbutamol, but not salmeterol, as needed to cause rapid relief of bronchospasm. Unfortunately the most effective dosage of beta2-agonists may increase above that recommended during acute exacerbations. In this study, we compared the acute effects of higher than customary doses of salmeterol and salbutamol in 20 patients with acute exacerbation of COPD. A dose-response curve to salmeterol pMDI, 25 microg/puff or salbutamol pMDI, 100 microg/puff, was constructed using 1, 1, and 2 puff' i.e., a total cumulative dose of 100 microg salmeterol or 400 microg salbutamol on 2 consecutive days. After baseline measurements, dose increments were given at 30-min intervals with measurements being made 25 min after each dose. Hear rate (HR) and pulse-oximetry (SpO2) measurements were then taken. Both salmeterol and salbutamol induced a larg and significant (P < 0.05) dose-dependent increase in FEV1 [mean differences from baseline (L) = after 100 microg salmeterol 0.174 (95% CI: 0.112 to 0.237); after 400 microg salbutamol: 0.165 (95% CI: 0.080 to 0.249)], in IC [mean differences from baseline (L) = after 100 microg salmeterol: 0.332 (95% CI: 0.165 to 0.499); after 400 microg salbutamol: 0.281 (95% CI: 0.107 to 0.456)] (Fig. 2), and in FVC mean differences from baseline (L) = after 100 microg salmeterol: 0.224 (95% CI: 0.117 to 0.331); after 400 microg salbutamol: 0.242 (95% CI: 0.090 to 0.395)]. There was no significant difference between the FEV1 values (P=0.418), the ICvalues (P=0.585), and the FVCvalue (P=0.610) after 100 microg salmeterol and 400 microg salbutamol. HR [mean differences from baseline (beats/min) = after 100 microg salmeterol: 3.15 (95% CI: -0.65 to 6.96); after 400 microg salbutamol: 2.30 (95% CI: -0.91 to 5.51)] and SpO2 [mean differences from baseline (%) = after 100 microg salmeterol: -0.20 (95% CI: -1.00 to 0.60); after 400 microg salbutamol: -0.11 (95% CI: -1.00 to 0.79)] did not change significantly from baseline (P > 0.05). These data indicate that salmeterol is effective and safe in the treatment of acute exacerbation of COPD and support its use in this clinical condition.

Addition of an extra dose of salmeterol Diskus to conventional dose of salmeterol Diskus in patients with COPD

Patients experiencing dyspnoea can request an additional dose of salmeterol during the dose interval for the control of their symptoms, although under treatment with salmeterol. In this study we have explored the effects on respiratory function of an additive dose of salmeterol Diskus in 15 chronic obstructive pulmonary disease (COPD) patients in regular treatment with a conventional dose of 50 microg salmeterol. On two different days, patients inhaled 50 microg Diskus. After 240 min, they inhaled additional 50 microg salmeterol Diskus (salmeterol arm) or placebo Diskus (placebo arm). Lung function was controlled before first drug administration and 0.5, 1, 2, 3, 4, 4.5, 6, 8, 10, and 12 h thereafter. The mean (95% CI) peak increase in FEV1 from baseline was reached after 4 h in the salmeterol arm (0.174 L; 0.144-0204) and after 5 h (0.141 L; 0.115-0.168) inthe placebo arm; after 12 h, the mean (95% Cl) increase in FEV1 from basal values was still 0.149 L (0.119-0.179) in salmeterol arm, but only 0.041 L (0.017-0.064) in placebo arm. The mean (95% CI) FEV1 AUC0-12h for all patients were 2.01 (1.72-2.30) L when salmeterol was added and 1.30 (1.03-1.58) L when placebo was inhaled. The difference (mean; 95% CI) between the FEV1 AUC0-12h of the two arms (0.71 L; 0.47-0.95) was statistically significant (P<0.0001), although the difference (mean; 95% CI) between the FEV1 AUC0-4h of the two treatments (0.08 L; -0.02-0.18) was notstatistically significant (P=0.126). The addition of an extra dose of salmeterol did not significantly increase the heart rate or decrease the SpO2. This study suggests that the addition of an extra dose of salmeterol does not give room for further increase in peak FEV1, but the effect of adding salmeterol to salmeterol is largely additive when considering the duration of action and safe.

Association between inhaled beta-agonists and the risk of unstable angina and myocardial infarction

BACKGROUND

beta-Adrenoceptor agonists (beta-agonists) are commonly used to treat obstructive lung diseases, and preliminary studies have suggested they are associated with an increased risk of adverse cardiovascular outcomes. We further examined the association between acute coronary syndromes and inhaled beta-agonist therapy.

METHODS

We performed a nested, case-control study using data that were collected as part of a larger, ongoing, prospective study of quality improvement in the primary care clinics of seven Veterans Administration Medical Centers. We identified 630 patients with unstable angina or acute myocardial infarction hospitalized between 1996 and 1999. We frequency matched these case patients to 10,486 control subjects according to clinic location, and randomly assigned each an "index date." The computerized pharmacy database at each center was used to ascertain beta-agonist use. Cardiovascular risk factors were assessed from mailed questionnaires and electronic medical records, which included inpatient and outpatient diagnoses, medications, and laboratory results.

RESULTS

In comparison with patients who had not filled a beta-agonist prescription during the 90 days prior to their index date, patients who had filled a beta-agonist prescription had an increased risk of experiencing an acute coronary syndrome. The increased risk of an acute coronary syndrome persisted after adjusting for age and cardiovascular risk factors, including hypertension, diabetes, and smoking history. Moreover, there was a dose-response relationship with an adjusted odds ratio (OR) of 1.38 for one to two metered-dose inhaler (MDI) canisters (95% confidence interval [CI], 0.86 to 2.23), an OR of 1.57 for three to five MDI canisters (95% CI, 1.01 to 2.46), and an OR of 1.93 for six or more MDI canisters (95% CI, 1.23 to 3.03). After stratifying for receipt of a beta-blocker prescription, the adjusted OR in subjects who did not receive a beta-blocker was 1.55 for one to two MDI canisters (95% CI, 0.60 to 3.99), an OR of 4.07 for three to five canisters (95% CI, 2.17 to 7.64), and an OR of 3.83 for six or more canisters (95% CI, 2.02 to 7.29). Subjects who had received both beta-blockers and beta-agonists had no increase in risk in acute coronary syndromes unless they had filled six or more beta-agonist MDI canisters.

CONCLUSIONS

A prescription for inhaled beta-agonists may increase the risk of myocardial infarction and unstable angina in patients with COPD.

Bronchodilator therapy and hyperactivity in preschool children

The common report of parents of asthmatic children that inhaled/nebulised salbutamol causes overactive behaviour was investigated. Nineteen children were assessed in a standardised setting before and after the administration of nebulised salbutamol and placebo. Neither parental report nor observer ratings suggested any significant increase in the child's level of activity.

Risk of myocardial ischaemia and beta-adrenoceptor agonists

Modern therapy for both cardiovascular disease and obstructive lung disease involves diametrically opposed manipulations of the beta-adrenoceptor. Beta-agonists reduce airflow limitation and improve symptoms among patients with obstructive lung disease while beta-blockers reduce symptoms, recurrent myocardial ischaemia and all-cause mortality among patients with ischaemic heart disease. There is biological plausibility for beta-agonists leading to adverse cardiovascular outcomes, and observational trials have raised concern about the safety of beta-agonists among patients with cardiovascular disease. Although there are many potential causal and noncausal explanations for these observational findings, the implications from these studies are the same. Physicians should be careful when prescribing beta-agonists for patients at risk for ischaemic heart disease. Furthermore, careful consideration should be given to distinguish symptoms caused by cardiovascular versus respiratory aetiologies.

Inhibition of tracheal vascular extravasation by liposome-encapsulated albuterol in rats

PURPOSE

To develop a liposome-based system for systemic delivery of anti-inflammatory drugs to airways and other inflamed tissues.

METHODS

Postcapillary venular gap junctions open during airway inflammation and allow fluid accumulation and permit molecules (e.g. complement, kininogen) to enter tissues, initiating inflammatory cascades. Beta-adrenergic agonists prevent inflammatory plasma extravasation, but because of their deleterious side effects, they are not used intravenously. When sterically stabilized "stealth" liposomes are injected i.v., they remain in the circulation for long periods. Inflammatory mediators [e.g., substance P(SP)] open postcapillary venular gaps and allow liposomes and their contents to be deposited selectively in the inflamed tissue.

RESULTS

We hypothesized that liposomes encapsulating a beta-adrenergic agonist, such as albuterol, would deposit selectively in inflamed airway tissue, where the drug would slowly leak out of the liposomes, resulting in closure of the gaps, thus preventing subsequent inflammatory extravasation. To test this hypothesis, we delivered albuterol-loaded liposomes i.v. in rats. Then we injected SP to open the venular gaps and allow accumulation of the drug-loaded liposomes in airway tissue. We examined whether this treatment resulted in inhibition of subsequent plasma extravasation induced by SP. The results indicate that liposome-encapsulated albuterol inhibits subsequent extravasation, presumably by leaking out of liposomes in airway tissue. This inhibition occurs for prolonged periods of time and with limited side effects compared to the effect of free albuterol.

CONCLUSIONS

We conclude that liposomes loaded with appropriate drugs, by migrating to inflamed tissue and subsequently inhibiting inflammatory cascades, may be of therapeutic value in inflammatory diseases.

Influence of hypoxia and hypercapnia on the kinetics and hypokaliaemic effect of salbutamol in the rabbit

1. The aims were to document the influence of moderate hypoxia or hypercapnia on salbutamol kinetics and its hypokaliaemic effect, following its administration through the intravenous (60 micrograms/kg), intratracheal (60 micrograms/kg), and oral (2400 micrograms/kg) routes (n = 5). In control animals, PaO2 was around 85 mmHg and PaCO2 20 mmHg; in hypoxic animals PaO2 was around 40 mmHg and in the hypercapnic rabbit PaCO2 was 50 mmHg. 2. Following the intravenous administration of salbutamol, the apparent volume of distribution increased two-fold (p < 0.05) in animals with hypoxia and hypercapnia. Consequently, its half life was enhanced (p < 0.05). Given via the trachea, salbutamol bioavailability was decreased by hypoxia. 3. When salbutamol was given orally, hypoxia or hypercapnia increased the area under salbutamol plasma concentration as a function of time (p < 0.05). 4. In control animals, the salbutamol hypokaliaemic effect was greater when administered orally than through the other routes. Compared with control animals, the experimental conditions reduced the hypokaliaemic effect of salbutamol only when given orally. 5. It is concluded that salbutamol kinetics and dynamics can be altered by hypoxia and hypercapnia.

Clinical efficacy and safety of clenbuterol HCl when administered to effect in horses with chronic obstructive pulmonary disease (COPD)

A field study of 239 horses was conducted to determine the efficacy and safety of clenbuterol HCl, a beta 2-adrenergic bronchodilator, when administered incrementally to effect in the treatment of chronic obstructive pulmonary disease (COPD). The severity of COPD (heaves) and response to treatment was determined by clinical evaluation; an overall 'heaveiness rating' (OHR) was assigned at each observation. The horses were treated orally b.i.d. with clenbuterol (as Ventipulmin Syrup), beginning with the lowest dosage of 0.8 micrograms/kg. On day 10 of treatment at the effective dose (0.8, 1.6, 2.4 or 3.2 micrograms/kg), treatment was either withdrawn (Schedule A) or continued for an additional 20 days (Schedule B). Horses on Schedule A demonstrated a significant improvement in the mean OHR on treatment Day 10 compared to the baseline overall heaveiness rating (BOHR) and a significant increase in the mean OHR (relapse) after the drug was withdrawn. Schedule B horses showed significant improvement (compared to BOHR) on treatment Days 10, 20 and 30. Incremental dosing with clenbuterol provided clinical improvement in 75% of the horses with a lower 95% confidence limit of 71%. Twenty-five percent were nonresponders. A greater percentage of the more severely affected horses required the 3.2 micrograms/kg dosage or were nonresponders compared to horses with a lower BOHR. Side effects of sweating, muscle tremor, and nervousness were of low intensity (mild to moderate) and frequency (< 7% of all observations) due to the regimen of incremental dosing to effect.

Tissue distribution of 3H-terbutaline in rabbits

Terbutaline is a widely used, selective beta 2-adrenergic agonist whose penetration into brain has not been demonstrated in laboratory animals. Although its tissue uptake has been reported in some animals, no uptake into brain has been demonstrated. A single dose of 20 microCi of 3H-terbutaline along with 10 mg/kg of unlabeled terbutaline was injected into a rabbit marginal ear vein. The distribution of 3H-terbutaline in several tissues was determined 0.5, 1, 3, or 6 hr later. Radioactivity in the brain was well-maintained over the 6 hr observation period. In most tissues, radioactivity peaked in less than 1 hr, then declined. Radioactivity in the urine was high at all time periods and was highest at 3 hr. Thus, terbutaline or a metabolite(s) does cross the blood-brain barrier in rabbits, and the radioactivity in the rabbit brain does not decrease during the 6 hours following terbutaline injection.

Hypokalemia after pediatric albuterol overdose: a case series

Sympathomimetic use results in a triad of hypokalemia, hyperglycemia, and elevated white blood cell count. Transient hypokalemia results from activation of the Na+/K+ pump and transport of potassium intracellularly. Increased serum glucose and insulin may also contribute to the intracellular shift of potassium after sympathomimetic use. Four cases of accidental pediatric albuterol ingestion with significant hypokalemia are reported. Four children between 1 and 6 years of age presented to the emergency department within 5 hours of ingesting 3.0, 1.1, 3.7, and 1.7 mg/kg albuterol, respectively. All four presented alert and oriented in no apparent distress. The most common findings were vomiting, sinus tachycardia, and hypokalemia (2.3, 2.5, 2.8, and 2.5 mmol/L, respectively). Each child received a single dose of activated charcoal and intravenous potassium replacement. All patients recovered uneventfully within 12 to 24 hours with supportive care only. These cases demonstrated that significant depressions in serum potassium can occur after pediatric albuterol overdose. Although transient, the dose-response relationship and duration of effect is unknown. Although significant hypokalemia can occur after ingestion of oral sympathomimetics, replacement should be managed on an individual basis until further studies are completed.

Cardiac arrhythmias after inhaled bronchodilators in patients with COPD and ischemic heart disease

Selective beta 2-agonist aerosols may produce significant cardiovascular effects. In the present study we used Holter monitoring to compare the arrhythmogenic effects of inhaled terbutaline (TE), a beta 2-agonist, with that of ipratropium bromide (IB), a nonabsorbable cholinergic drug. Fourteen patients with concomitant obstructive lung disease, ischemic heart disease, and complaints of postinhalation palpitations were studied in a random, double-blind, cross-over fashion. Both drugs significantly improved vital capacity and FEV1. Heart rate and the frequency of premature beats were not significantly affected by the bronchodilators. We conclude that no clear connection between inhaled bronchodilators and arrhythmias could be demonstrated.

A placebo-controlled dose-finding study with bambuterol in elderly patients with asthma

A new long-acting bronchodilator prodrug, bambuterol hydrochloride, was tested in a randomized, crossover, and double-blind study in elderly asthmatic patients (aged 64 to 82 years). They received placebo and 5-mg, 10-mg, and 20-mg tablets once daily for a week at each dose. The plasma concentration of the active metabolite, terbutaline, increased linearly with the dose of drug (p < 0.001). Peak expiratory flow rate increased with dose in the morning (p < 0.001 for 10-mg and 20-mg doses) and afternoon (p < 0.05 for 10 mg; p < 0.001 for 20 mg) and was different from placebo for the 10-mg/d and 20-mg/d regimens. The use of supplemental inhaled beta 2-adrenergic agonist therapy was reduced during the night for the 10-mg (p < 0.05) and 20-mg (p < 0.01) doses in comparison to placebo. No significant effects of treatment on blood pressure and pulse were demonstrated. Tremor and palpitations were mild and related to the dose. These data suggest that treatment once daily with bambuterol hydrochloride in a dose of 10 or 20 mg improves pulmonary function and is well tolerated as bronchodilator therapy in elderly patients with asthma.

The use of beta-agonists and the risk of death and near death from asthma

BACKGROUND

Morbidity and mortality from asthma appear to be increasing, and it has been suggested that medications used to treat asthma are contributing to this trend. We investigated a possible association between death or near death from asthma and the regular use of beta 2-agonist bronchodilators.

METHODS

Using linked health insurance data bases from Saskatchewan, Canada, we conducted a matched case-control study of subjects drawn from a cohort of 12,301 patients for whom asthma medications had been prescribed between 1978 and 1987. We matched 129 case patients who had fatal or near-fatal asthma with 655 controls (who had received medications for asthma but had not had fatal or near-fatal events) with respect to region of residence, age, receipt of social assistance, and previous hospitalization for asthma.

RESULTS

The use of beta-agonists administered by a metered-dose inhaler was associated with an increased risk of death from asthma (odds ratio, 2.6 per canister per month; 95 percent confidence interval, 1.7 to 3.9) and of death or near death from asthma, considered together (odds ratio, 1.9; 95 percent confidence interval, 1.6 to 2.4). For death from asthma, use of the beta-agonist fenoterol was associated with an odds ratio of 5.4 per canister, as compared with 2.4 for the beta-agonist albuterol. On a microgram-equivalent basis, the odds ratio for this outcome with fenoterol was 2.3, as compared with 2.4 with albuterol.

CONCLUSIONS

An increased risk of death or near death from asthma was associated with the regular use of inhaled beta 2-agonist bronchodilators, especially fenoterol. Regardless of whether beta-agonists are directly responsible for these adverse effects or are simply a marker for more severe asthma, heavy use of these agents should alert clinicians that it is necessary to reevaluate the patient's condition.

Clinical complexity and epidemiologic uncertainty in case-control research. Fenoterol and asthma management

Two recent epidemiologic case-control studies suggested that fenoterol, a selective beta-adrenergic agonist, was associated with an increase in the risk of asthma death. The results of these studies were criticized because of methodologic problems in the choice and selection of control subjects; the different methods used to gather exposure data in cases and control subjects; and because of inadequate classification and adjustment for asthma severity. In response to this controversy, a new study is underway, the Saskatchewan Asthma Epidemiology Project. The SAEP includes two complementary studies, an historic cohort and a case-control analysis, that employ the computerized databases of the Saskatchewan Health Department. A unique aspect of the SAEP is the attempt to incorporate knowledge of asthma physiology and management into the design of the studies. Specifically, the study design recognized the role of antiinflammatory drugs in asthma treatment; the distinction between asthma death and near-fatal asthma; the severity of asthma; patterns of drug use; and the distinction between inadequate clinical care and disease severity. The strategies we employed in the SAEP may prove helpful to investigators whenever clinical and biologic processes create sources of potential bias requiring special procedures for the design and analysis of epidemiologic studies.

Sympathomimetics for acute severe asthma: should only beta 2-selective agonists be used?

Sympathomimetics have become a mainstay of the treatment of acute asthma. Aerosolization of sympathomimetics provides as great or greater bronchodilation in acute severe asthma with fewer systemic effects than parenteral therapy. Despite the broncho-selectivity achieved with this route of administration, cardiostimulation remains the major, dose-limiting factor in the safe use of sustained, high-dose therapy with these agents. This article reviews the pharmacology, adverse effects, and toxicities of selected beta agonists, as well as clinical studies relevant to the question posed in the title. Although the ideal study to answer this question has not yet been performed, the authors feel that available evidence supports the preferential use of selective beta 2 agonists in patients with acute, severe asthma who will require high doses of beta agonists.

Adrenoceptors in airway smooth muscle

This review examines the roles and functional significance of alpha and beta-adrenoceptor subtypes in airway smooth muscle, with emphasis on human airway function and the influence of asthma. Specifically, we have examined the distribution of beta-adrenoceptors in lung and the influence of age, the epithelium, respiratory viruses and inflammation associated with asthma on airway smooth muscle beta-adrenoceptor function. Sites of action, beta 2-selectivity, efficacy and tolerance are also examined in relation to the use of beta 2-agonists in man. In addition, alpha-adrenoceptor function in airway smooth muscle has been reviewed, with some emphasis on comparing observations made in airway smooth muscle with those in animal models.