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The surge in COVID-19 cases during the 2020 Spring led to a nationwide shortage of albuterol inhalers. As a new surge has begun, shortages may make it difficult for patients with obstructive lung disease, including children with asthma, to obtain refills. Since there is no evidence that albuterol relieves symptoms in COVID-19 patients with respiratory symptoms not caused by bronchospasm, it is reasonable for clinicians to not prescribe it for COVID-19 patients unless they also have asthma or chronic obstructive pulmonary disease.

This case report demonstrates a small repetition of the case series carried out in Italy wherein inhaled adenosine was administered to patients experiencing severe and worsening coronavirus disease-2019 (COVID-19). The two cases are important not only because they were the first of their type in the United States, but also because both patients were DNR/DNI and were therefore expected to die. Study repetition is vitally important in medicine. New work in pharmacology hypothesizes that adenosine-regulator proteins may play a role in the pathogenesis of COVID-19 infection. Furthermore, adenosine, by interacting with cell receptor sites, has pluripotent effects upon inflammatory cells, is anti-inflammatory, and is important in tissue hypoxia signaling. Inhaled adenosine is potentially safe; thousands have received it for asthmatic challenge testing. The effects of adenosine in these two cases were rapid, positive, and fit the pharmacologic hypotheses (as seen in prior work in this journal) and support its role as a therapeutic nucleoside.

BACKGROUND AND OBJECTIVES: The albuterol dropper bottle used to prepare solutions for continuous nebulization contains the preservative benzalkonium chloride (BAC). BAC, by itself, has been shown to cause bronchospasm. We hypothesized that BAC would decrease the therapeutic efficacy of albuterol in patients with acute asthma exacerbations. METHODS: We performed a retrospective cohort study comparing the clinical outcomes of patients RESULTS: A total of 477 patients were included in the analysis (236 exposed to BAC and 241 controls). The duration of continuous nebulization was significantly longer in the BAC group than in the control group (median of 9 vs 6 hours; 15.7% required continuous nebulization compared to 5.8% of controls at 24 hours). The control group was 79% more likely to stop continuous nebulization at any particular point in time (hazard ratio 1.79; 95% confidence interval: 1.45 to 2.22; P < .001) and 43% more likely to stop additional respiratory support (hazard ratio 1.43; 95% confidence interval: 1.16 to 1.75; P < .001). CONCLUSIONS: BAC is a functional albuterol antagonist associated with a longer duration of continuous albuterol nebulization treatment and additional respiratory support, suggesting that preservative-free albuterol formulations are safer for use in continuous nebulization.

Background: Poor adherence with inhaled corticosteroid (ICS) medication is common in the pediatric population and can result in poor asthma control with increased frequency of asthma-related complications. The purpose of this study was to determine whether or not the initiation of ICS administration twice per day at school/daycare in patients with poor medication adherence at home improves asthma health care outcomes. Methods: We retrospectively selected patients followed by our Pediatric Pulmonology Clinic who had poorly controlled asthma and had been assigned to receive ICS twice daily at school/daycare due to poor adherence with ICS therapy. We analyzed the number of short courses of oral corticosteroids, hospital admissions, emergency department visits, and intramuscular methylprednisolone administrations for asthma exacerbations for the year before and after the intervention. The Wilcoxon signed rank test with continuity correction was used in the primary analysis. Results: Forty-nine patients who met the inclusion criteria were identified, but only 40 actually started the intervention. The number of oral corticosteroid courses per year decreased from 1.35 ± 1.1 before the intervention to 0.68 ± 1.2 (P = 0.008) postintervention, hospital admissions per year decreased from 0.45 ± 0.7 to 0.10 ± 0.3 (P = 0.006), emergency department visits per year decreased from 0.55 ± 0.8 to 0.28 ± 0.6 (P = 0.084), and intramuscular repository methylprednisolone injections per year for asthma exacerbations decreased from 0.20 ± 0.4 to 0.10 ± 0.3 (P = 0.23). Conclusion: These results indicate that school/daycare administration of ICS may be an effective option to improve indicators of asthma exacerbations in children with poor adherence to ICS at home.

Objectives Little is known about emergency medical services' (EMS') management of pediatric asthma. This study's objective was to describe the demographic, clinical, and geographic characteristics of current EMS' management of pediatric asthma in the state with the fourth-largest pediatric population. Methods This was a retrospective observational study of EMS patients ages 2 to 18 years with an asthma exacerbation from 2011 to 2016. Patients from Florida's EMS Tracking and Reporting System were included if their EMS chief complaint indicated respiratory distress, if they received at least 1 albuterol treatment, and if they were transported to a hospital. Results A total of 11,226 patients met the inclusion criteria. The median age was 9 years, and 49% were African-American. Geospatial analysis revealed 4 rural counties with disproportionate numbers of African-American patients. In addition to albuterol, 37% of patients received ipratropium bromide and 9% received systemic corticosteroids. Adjusted logistic regression revealed that the strongest predictors of receiving systemic corticosteroids from EMS were intravenous access (odds ratio, 33.4; 95% confidence interval, 24.4-45.6) and intravenous magnesium sulfate administration (odds ratio, 5.0; 95% confidence interval, 3.4-7.3), indicating a more severe presentation. Conclusions This statewide study demonstrated low rates of EMS administration of ipratropium bromide and systemic corticosteroids, both evidence-based treatments for asthma exacerbations. Targeted EMS education should attempt to increase utilization of both those medications. In addition, the feasibility and efficacy of EMS administration of oral systemic corticosteroids for children should be explored.

Background Pediatric asthma exacerbations are a frequent reason for emergency care. Early administration of oral systemic corticosteroids (OCS) in the emergency department (ED) decreases hospitalization rates and ED length-of-stay (LOS). However, it is unknown whether even earlier OCS administration by emergency medical services (EMS) in the prehospital setting further improves outcomes. Purpose To describe the background and methods of a type 1 hybrid effectiveness-implementation trial of EMS-administered OCS for pediatric asthma patients incorporating a stepped wedge design and the RE-AIM framework. Methods The study employs a non-randomized stepped wedge design where multiple EMS agencies adopt OCS as a treatment for pediatric asthma exacerbations at varying times. This design accommodates ethical considerations of studying pediatric subjects in the prehospital setting where informed consent is not feasible. We will compare hospitalization rates, ED LOS, and short-term healthcare costs between pediatric asthma patients who do and do not receive OCS from EMS. Using geographic information systems (GIS), we will measure how differences in outcomes scale with increasing EMS transport time. We will use the RE-AIM framework to guide a mixed methods analysis of barriers and enablers to EMS administration of OCS for pediatric asthma patients, including quantitative measures of adoption and uptake and qualitative EMS provider focus group data. Conclusion This trial will determine if earlier EMS administration of OCS to pediatric asthma patients decreases hospitalizations, ED LOS, and short-term healthcare costs, and if those outcomes scale with longer EMS transport times. We will identify barriers and enablers to implementing EMS-administered OCS for pediatric asthma patients.

In 2006, the US FDA issued a ‘Guidance for Industry’ regarding submission of New Drug Applications for pancreatic enzyme replacement therapy (PERT) products. Five oral delayed-release PERT products have been approved by the FDA, and several others are under development and/ or evaluation for New Drug Application submission. We present in this paper recommendations of the Cystic Fibrosis Foundation's Cystic Fibrosis (CF) Therapeutics Development Network and Data Safety Monitoring Board regarding study design considerations for evaluating PERT products in patients with CF. Careful attention to study design and accuracy of the outcome measures has confirmed our understanding of the efficacy and safety of PERT for the treatment of exocrine pancreatic insufficiency of CF.

Omalizumab is a recombinant DNA-derived humanized immunoglobulin G (IgG) anti-IgE monoclonal antibody approved for use in patients with allergic asthma. However, it is not approved for allergic bronchopulmonary aspergillosis (ABPA). Conflicting reports exist about the effects of omalizumab on ABPA in patients with cystic fibrosis (CF). We report 2 patients with CF treated with omalizumab, in whom frequency of ABPA exacerbations was markedly reduced with treatment. Additionally, hospitalizations were reduced from 5 per year to once in 18 months in the first patient and from twice to once per year in the second patient. Free IgE decreased by 87.9% after 6 months of therapy in the first patient and by 95.6% after 7 months of therapy in the second patient. Neither of the two patients had evidence of asthma. Omalizumab may be useful in treating ABPA in patients with CF, and including free IgE in monitoring the response to therapy will be helpful.

BACKGROUND: Decreasing electrostatic charge on valved holding chambers increases the amount of drug delivered. However, there are no data demonstrating that this increases bronchodilatation. OBJECTIVE: To investigate the influence of reducing electrostatic charge on the bronchodilator response to albuterol inhaler during nocturnal bronchospasm. METHODS: This randomized double-blind, double-dummy crossover study included subjects, 18–40 years old, with nocturnal bronchospasm (20% overnight decrease in peak flow on 3 of 7 nights during run-in), FEV1 60–80% predicted during the day, and ≥ 12% increase after albuterol. Subjects slept in the clinical research center up to 3 nights for each treatment. FEV1 and heart rate were measured upon awakening spontaneously or at 4:00 am, and 15 min after each dose of 1, 2, and 4 cumulative puffs of albuterol via metered-dose inhaler. The drug was administered through an anti-static valved holding chamber (AeroChamber Plus Z-Stat) or a conventional valved holding chamber containing a static charge (AeroChamber Plus). RESULTS: Of 88 consented subjects, 11 were randomized and 7 completed the study. Most exclusions were due to lack of objective evidence of nocturnal bronchospasm. Upon awakening, FEV1 was 44 ± 9% of predicted before the anti-static chamber and 48 ± 7% of predicted before the static chamber. The mean ± SD percent increase in FEV1 after 1, 2, and 4 cumulative puffs using the anti-static versus the static chamber, respectively, were 52 ± 26% versus 30 ± 19%, 73 ± 28% versus 48 ± 26%, and 90 ± 34% versus 64 ± 35%. The point estimates for the differences (and 95% CIs) between the devices (anti-static vs static) were 21% (4–38%) (P = .03), 23% (6–41%) (P = .02), and 25% (7–42%) (P = .01) for 1, 2, and 4 cumulative puffs, respectively. There was no significant difference in heart rate between treatments. CONCLUSIONS: Delivery of albuterol through an anti-static chamber provides a clinically relevant improvement in bronchodilator response during acute, reversible bronchospasm such as nocturnal bronchospasm.

We determined lung bioavailability of a fluticasone propionate (FP) pressurised metred-dose inhaler (Flovent HFA; GlaxoSmithKline, Research Triangle Park, NC, USA) administered via AeroChamber Plus (Monaghan Medical, Plattsburgh, NY, USA) with Facemask and Babyhaler (GlaxoSmithKline) valved holding chambers (VHCs) using a population pharmacokinetic approach. Children from 1 to

Inhaled long-acting β2-adrenergic agonists (LABAs) are recommended in the treatment of asthma as maintenance therapy when combined with an inhaled corticosteroid or when used alone to prevent exercise-induced bronchospasm.1 In addition, they are recommended alone or in combination with a long-acting inhaled anti-cholinergic or an inhaled corticosteroid as maintenance therapy for chronic obstructive pulmonary disease.2 Formoterol, salmeterol, and arformoterol are the only LABAs currently available in the United States, and they are marketed in various formulations alone or in combination with an inhaled corticosteroid. Although patents are still in force for several drug products containing a LABA (i.e., drug and device), the patents on the drug substance (i.e., the drug alone) have expired. Therefore, pharmaceutical firms have developed or are interested in developing alternative delivery devices for two of these drugs, and in some cases attempts are being made to develop a generic version. Obtaining U.S. Food and Drug Administration (FDA) approval of a generic LABA includes a requirement for an in vivo dose-response study to establish bioequivalence,3 and under varying circumstances, such a study is required by the European Medicines Agency4 and Canada’s Human Protection Branch.5 The purpose of such a study is to determine whether a test and reference product meet equivalence criteria based on a bioassay sensitive to differences in dose. If the study design is not sufficiently sensitive to detect a difference in two doses of the reference product, then it would not be possible to detect a difference between the test and reference products in the amount of drug delivered to the airways.6 In the United States, pharmacokinetic studies are not sufficient, by themselves, to establish a dose-response relationship,3 since plasma concentrations have not been proven to indicate where in the airways the drug is delivered and do not distinguish drug absorbed from the lungs and drug absorbed from the swallowed portion of the dose in the gastrointestinal tract.7 Thus, a pharmacodynamic end point is required to demonstrate the amount of drug delivered to the relevant receptors in the airways.8 Conventional bronchodilator studies, where the forced expiratory volume in 1 second (FEV1) is measured after a dose over time, have been used, but often the dose-response curve with this pharmacodynamic end point is relatively flat.9, 10 That is, during typical daytime studies in patients with stable asthma, one actuation may produce the same improvement in FEV1 as two actuations, since the response lies on the upper plateau portion of the dose-response curve.10 Dose-response studies of albuterol have demonstrated that bronchoprovocation with histamine or methacholine are the most sensitive methods of determining differences in doses when delivered by generic and brand chlorofluorocarbon (CFC) metered-dose inhalers (MDIs),11 between a CFC MDI and dry powder inhaler (DPI),12 and between CFC and hydrofluoroalkane (HFA) MDIs.13 Bronchoprovocation with methacholine has been used to compare the intensity and/or duration of formoterol delivered by a DPI or MDI.14–16 However, none of these studies has provided sufficient information to determine whether methacholine challenge can detect a 2-fold or smaller difference in dose and, thus, be useful as a bioassay to determine bioequivalence. Also, they do not provide information on the sample size required for a bioequivalence study. Since the Aerolizer (Foradil Aerolizer; Schering Corp., Kenilworth, NJ) is the only DPI formulation of formoterol available in the United States, it will serve as the reference product for subsequent studies of new delivery devices or generic formulations of this drug. Thus, the purpose of this study was to determine whether a methacholine-based clinical bioassay can be used to evaluate bioequivalence of formoterol (Aerolizer) and other formoterol-containing formulations. This would require that a highly significant dose-response relationship be present, which, in turn, requires a sufficiently steep dose-response slope relative to the response variability observed in the study. In addition, we propose possible improvements in study design that may further increase the statistical power of these bioequivalence methods.

BACKGROUND We sought to compare the differences of coefficient of fat absorption (CFA) and coefficient of nitrogen absorption (CNA) in healthy individuals and those with cystic fibrosis (CF) and to study the precision of CFA and CNA.METHODS Sixteen healthy and 23 subjects with CF and pancreatic insufficiency ate a high-fat, high-protein diet for 72 hours; stool was collected between blue food dye markers to determine CFA and CNA. Subjects with CF withheld pancreatic enzymes. Tests were repeated on 5 of the CF and 10 of the healthy subjects.RESULTS In healthy subjects, mean CFA was 93.5% ± 2.7%; mean CNA was 88.1% ± 5%. Median test-retest in 10 healthy subjects was +0.7% CFA (range, −8.1% to + 5.9%) and +0.9% CNA (range, −14.6% to +6.8%). For subjects with CF, mean CFA was 38.5% ± 14.7% and mean CNA was 52.2% ± 11.4%. Median test-retest change in 5 subjects with CF was −6.9% CFA (range, −19.7% to +42.8%) and +14.7% CNA (range, −6.4% to +42.8%).CONCLUSIONS CFA and CNA have inconsistent precision in CF. The limitations of CFA as a measure of steatorrhea correction in CF should be recognized in studies of pancreatic enzyme supplements.

The presentations at the Orlando Inhalation Conference on pharmacokinetic (PK) studies indicated that PK is the most sensitive methodology for detecting formulation differences of oral inhaled drug products (OIDPs) that have negligible gastrointestinal bioavailability or for which oral absorption can be prevented (e.g., ingestion of charcoal). PK studies, therefore, may represent the most appropriate methodology for assessing local and systemic bioequivalence (BE). It was believed by many (but not all participants) that potential differences between formulations are more likely to be detected in healthy adult volunteers, as variability is reduced while deposition to peripheral areas is not restricted. A study design allowing assessment and statistical consideration of intra-subject and inter-batch variability within the evaluation of BE studies was suggested, while optimal inhalation technique during PK studies should be enforced to decrease variability. Depending on the drug and in vitro method, in vitro tests may not detect differences in PK parameters. Harmonization of BE testing requirements among different countries should be encouraged to improve global availability of low cost OIDPs and decrease industry burden.

In the session on “Pharmacodynamic studies to demonstrate efficacy and safety”, presentations were made on methods of evaluating airway deposition of inhaled corticosteroids and bronchodilators, and systemic exposure indirectly using pharmacodynamic study designs. For inhaled corticosteroids, limitations of measuring exhaled nitric oxide and airway responsiveness to adenosine for anti-inflammatory effects were identified, whilst measurement of 18-h area under the cortisol concentration–time curve was recommended for determining equivalent systemic exposure. For bronchodilators, methacholine challenge was recommended as the most sensitive method of determining the relative amount of β-agonist or anti-muscarinic agent delivered to the airways. Whilst some agencies, such as the Food and Drug Administration (FDA), do not require measuring systemic effects when pharmacokinetic measurements are feasible, the European Medicines Agency requires measurement of heart rate and serum potassium, and some require serial electrocardiograms when bioequivalence is not established by pharmacokinetic (PK) studies. The Panel Discussion focused on whether PK would be the most sensitive marker of bioequivalence. Furthermore, there was much discussion about the FDA draft guidance for generic fluticasone propionate/salmeterol. The opinion was expressed that the study design is not capable of detecting a non-equivalent product and would require an unfeasibly large sample size.

Bronchospasm precipitated by exercise is often indistinguishable from bronchospasm produced by other stimuli. Symptoms result from airflow limitation and include wheezing, cough, chest tightness, dyspnea and sometimes hypoxemia. The prevalence of exercise-induced bronchospasm varies from 30%-90%, but virtually all patients with current asthma will experience a decrease in lung function if the exercise is sufficiently vigorous, especially in cold, dry environmental conditions. Exercise-induced bronchospasm is more prevalent in children than in adults, probably because children are physically more active. It is also more prevalent among elite winter sports athletes. The pathogenesis of exercise-induced bronchospasm involves a defect in respiratory heat exchange that probably triggers mast cell and eosinophil release of bronchoconstricting mediators. The goal of therapy is prevention of symptoms. This may be accomplished by pre-treating patients with isolated exercise-induced bronchospasm using an inhaled rapid-onset β2-adrenergic agonist before a scheduled activity or by treating the underlying inflammation when exercise-induced bronchospasm is part of the clinical syndrome of persistent asthma. In the later instance, either an inhaled corticosteroid, an oral leukotriene modifier, or a combination of both, depending on severity, may be required to prevent exercise-induced bronchospasm associated with activities of daily living. In addition, some of these patients may still require pre-treatment with a short-acting inhaled β2-agonist before a scheduled vigorous activity, especially in very cold ambient temperatures. Because the duration of bronchoprotection decreases with daily use (tachyphylaxis), long acting β2-adrenergic agonists (e.g., formoterol, salmeterol) have a limited role in treating exercise-induced bronchospasm.

Aims Previous bronchoprovocation studies indicate that nifedipine attenuates airway responsiveness to several stimuli whereas diltiazem has no effect. The aim of this study was to determine whether such studies predict the efficacy of calcium channel blockers as maintenance therapy for persistent asthma. Methods Twenty-one otherwise healthy adults with persistent asthma, mean age 25 years, completed treatment with maximum tolerated doses of placebo (P), nifedipine (N), and diltiazem (D) in a double-blind, randomized, three-treatment, three-period, crossover manner, each for 4 weeks. Frequency and severity of asthmatic symptoms were recorded twice daily, as well as peak expiratory flow and frequency of ‘prn’ use of inhaled terbutaline. Blood pressure, heart rate, P-R interval of the ECG and spirometry were measured biweekly. At the end of each treatment, airway responsiveness to exercise was measured. Results The mean (s.e. mean)% of days with wheeze was 69±7% during P, 75±6% during N and 72±6% during D (P=0.7). FEV1 was 79±2% of predicted during P, 81±2% during N and 79±2% during D (P=0.6). The decrease in FEV1 after exercise was 32±4% during P, 32±5% during N and 27±4% during D (P=0.5). Heart rate was elevated during N (P=0.0002) whereas P-R interval was prolonged during D (P=0.0001). Conclusions Maintenance therapy with calcium channel blockers, at doses that produce cardiovascular effects, do not suppress the signs and symptoms of persistent asthma. Previous bronchoprovocation studies did not predict these results.

Background Omalizumab, an anti-IgE monoclonal antibody, is administered by injection once or twice monthly in offices and clinics. It offers a potential alternative intervention for patients with allergic asthma that is not well controlled because of recalcitrant poor adherence to inhaled corticosteroid therapy. Objective To assess the effect of omalizumab therapy by measuring airway responsiveness to adenosine, a marker of allergic airway inflammation, and resource use. Methods Patients (N = 17) aged 6 to 26 years (mean age, 16.4 years) with poorly controlled persistent allergic asthma, less than 50% adherence to inhaled corticosteroid therapy, a forced expiratory volume in 1 second (FEV 1 ) of 60% predicted or higher, and adenosine provocation concentration that caused a decrease in FEV 1 of 20% (PC 20 ) of 60 mg/mL or less were randomized to receive 4 months of omalizumab or placebo in a double-blind, crossover trial with a 3- to 4-month washout between treatments. Patients were instructed to continue taking inhaled corticosteroids throughout the study. The PC 20 was measured before and after each period. Results Fifteen patients completed the study. The mean baseline PC 20 was 14.1 mg/mL (95% CI, 10.8–18.4 mg/mL). The fold change PC 20 was 0.9 (95% CI, 0.5–1.7) during placebo and 3.1 (95% CI, 1.6–6.2) during omalizumab treatment; the estimated ratio was 3.4 (95% CI, 1.2–9.3; P = .02). Six patients required one or more short courses of oral corticosteroids for asthma exacerbations during placebo, but none required this intervention during omalizumab. During the study, the median prescription refills for inhaled corticosteroids was 0.15 (95% CI, 0.00–0.33) canisters per month. Conclusion Omalizumab therapy is an alternative for patients with more severe poorly controlled asthma in whom adherence does not improve with conventional interventions. Trial Registration clinicaltrials.gov Identifier: NCT00133042.

Objective To examine the comparative effectiveness of inhaled long-acting beta-agonist (LABA), inhaled corticosteroid (ICS), and ICS/LABA combinations. Methods We used a retrospective cohort design of patients older than 12 years with asthma diagnosis in the Clinical Practice Research Datalink to evaluate asthma-related morbidity measured by oral corticosteroid (OCS) initiation within 12 months of initiating LABAs, ICSs, or ICSs/LABAs. Asthma severity 12 months before drug initiation (use of OCSs, asthma-related hospital or emergency department visits, and number of short-acting beta-agonist prescriptions) and during follow-up (short-acting beta-agonist prescriptions and total number of asthma drug classes) was adjusted as a time-varying variable via marginal structural models. Results A total of 51,103 patients with asthma were followed for 12 months after receiving first prescription for study drugs from 1993 to 2010. About 92% initiated ICSs, 1% initiated LABAs, and 7% initiated ICSs/LABAs. Compared with ICSs, LABAs were associated with a 10% increased risk of asthma exacerbations requiring short courses of OCSs (hazard ratio [HR] 1.10; 95% confidence interval [CI] 1.07–1.18). ICS/LABA initiators were 62% less likely than ICS initiators (HR 0.38; 95% CI 0.12–0.66) and 50% less likely than LABA initiators to receive OCS prescriptions for asthma exacerbations (HR 0.50; 95% CI 0.14–0.78). Conclusions In concordance with current asthma management guidelines, inhaled LABAs should not be prescribed as monotherapy to patients with asthma. The findings suggest the presence of time-dependent confounding by asthma severity, which was accounted for by the marginal structural model.

BACKGROUND: A study was undertaken to determine whether montelukast, a new potent cysteinyl leukotriene receptor antagonist, attenuates exercise-induced bronchoconstriction. The relationship between the urinary excretion of LTE4 and exercise-induced bronchoconstriction was also investigated. METHODS: Nineteen non-smoking asthmatic patients with a forced expiratory volume in one second (FEV1) of > or = 65% of the predicted value and a reproducible fall in FEV1 after exercise of at least 20% were enrolled. Subjects received placebo and montelukast 100 mg once daily in the evening or 50 mg twice daily, each for two days, in a three-period, randomised, double blind, crossover design. In the evening, approximately 20-24 hours after the once daily dose or 12 hours after the twice daily dose, a standardised exercise challenge was performed. Data from 14 patients were available for complete analysis. RESULTS: The mean (SD) maximal percentage decrease in FEV1 after exercise was 29.6 (16.0), 17.1 (8.2), and 14.0 (9.4) for placebo, once daily, and twice daily regimens, respectively. The mean (95% CI) percentage protection was 37 (15 to 59) for the group who received 50 mg twice daily and 50 (31 to 69) for those who received 100 mg once daily. Active treatments were not different from each other. The mean (SD) plasma concentrations of montelukast were higher after the twice daily regimen (1.27 (0.81) microgram/ml) than after the once daily regimen (0.12 (0.09) microgram/ml); there was no correlation between the percentage protection against exercise-induced bronchoconstriction and plasma concentrations. After exercise urinary excretion of LTE4 increased significantly during placebo treatment (from 34.3 to 73.7 pg/mg creatinine; p < 0.05) but did not correlate with the extent of exercise-induced bronchoconstriction. CONCLUSIONS: Montelukast protects similarly against exercise-induced bronchoconstriction between plasma concentrations of 0.12 and 1.27 micrograms/ml. The increase in the urinary excretion of LTE4 after exercise and the protection from exercise-induced bronchoconstriction with a cysteinyl leukotriene receptor antagonist provide further evidence of the role of leukotrienes in the pathogenesis of exercise-induced bronchoconstriction.

To determine whether the methacholine challenge method used for albuterol can be applied to assess long-acting β2-adrenergic agonist (LABA) bioequivalence, which would require a sufficiently steep dose-response curve.Prospective, unblinded, randomized, 2-way crossover study.University medical center clinical research laboratory.Ten adults, aged 21-58 years, with mild asthma (forced expiratory volume in 1 sec [FEV(1)] ≥ 70% predicted) and a baseline provocational concentration of methacholine required to decrease FEV(1) by 20% (PC(20)) of 4 mg/ml or less completed the study.Patients were randomized to receive a single dose of either 12 or 24 μg of formoterol delivered by a dry powder inhaler; 3-7 days later, at the same time of day, they received the other dose.The FEV(1) was measured before and 1 hour after dosing, followed by performance of a methacholine challenge. Statistical analysis was performed by the 2-sample regression method for crossover studies. The dose-response curve for bronchodilatation was flat; the mean ± SD increase in FEV(1) after formoterol 12 and 24 μg was 14 ± 5% and 14 ± 8%, respectively (p0.05). In contrast, the geometric mean PC20 (95% confidence interval) was 7 mg/ml (2-22 mg/ml) after the 12-μg dose and 16 mg/ml (5-45 mg/ml) after the 24-μg dose (p0.001).Bioassay by methacholine challenge will be useful for bioequivalence studies of LABAs. A sample of at least 28 patients will be required for formoterol when methacholine challenge is performed in an optimal manner. The sample size may differ for other LABAs.

Lung function (forced expiratory volume during one second, FEV 1 ), heart rate and albuterol (salbutamol) plasma levels were recorded in 11 subjects with mild intermittent asthma after oral administration of albuterol. Pulmonary and cardiovascular data of this and other studies were directly linked to the corresponding plasma concentrations via an Emax relationship, resulting in EC 50 values for the heart rate and lung function of 18 and 5 ng/ml, respectively. An integrated PK/PD analysis of these and previously reported data on fenoterol and terbutaline resulted in the following clinically relevant conclusions: (I) Albuterol and terbutaline are about 25-fold less active at the site of action than fenoterol; the three drugs show similar cardiac to bronchopulmonary selectivities. (II) The relative clinical activities after infusion decline in the following order: fenoterol (8) > terbutaline (2) > albuterol (1). (III) Significant differences in the oral bioavailability cause an opposite rank order after oral administration. (IV) The model related the higher systematic side effects after inhalation of fenoterol to an over-dosing problem.

Because chlorofluorocarbons (CFCs) contribute to depletion of stratospheric ozone, CFC-containing metered-dose inhalers (MDIs) such as Ventolin and Proventil are being phased out of production. In terms of delivery of albuterol to the lungs, we compared an alternative delivery system, the Spiros dry-powder inhaler (DPI), with Ventolin, using a methacholine challenge-based clinical bioassay. Twenty-four adults and adolescents with asthma completed this double-blind, four-period crossover study. Doses evaluated were one and three actuations each of Spiros and Ventolin (90- and 270-microgram albuterol base). A methacholine challenge (Cockcroft method) was initiated 3 h before and 0.25 h after albuterol. Predose PC(20)FEV(1) values were not significantly different between study days. Postdose PC(20)FEV(1) results met standard bioassay study validity criteria: i.e., a significant dose-response relationship was present (p = 0.0002); tests for deviation from parallelism and overlap of dose-response curves were nonsignificant (p = 0.08, 0.69). By using Finney 2-by-2 bioassay analysis, we estimate that each Spiros actuation delivers 1.12 times as much albuterol to the airways as one Ventolin actuation (90% confidence interval, 0.68 to 1.94). There were no significant differences in markers of systemic effects (vital signs, potassium, and blood glucose concentrations). We conclude that Spiros and Ventolin inhalers deliver comparable quantities of albuterol to the airways.

We performed this study to evaluate how age and device affect the systemic exposure of inhaled fluticasone propionate (FP) in children. The findings indicate an anti-static valved holding chamber significantly increases systemic exposure of FP.

Previous recommendations for weight adjusted theophylline dosage have not considered age as a contributing variable. The current data was collected in two parts. First, 23 children with chronic asthma, ages 4-15, received .8 mg/kg/hr intravenous infusions of theophylline until steady-state serum concentrations were documented. Clearance was then calculated (clearance = infusion rate % steady-state serum concentration). Subsequently, 156 children with chronic asthma, ages 2½ months to 16 years, received chronic oral theophylline in 4 doses/day titrated to achieve peak serum concentrations in the therapeutic range of 10 to 20 μg/ml (mean was 15 μg/ml). Clearances among the 23 children receiving the intravenous infusion averaged 1.35 ± .46 ml/kg/min (mean ± standard deviation), but correlated inversely with age (rS = −.46, p < .025). The 7 children over age 12 averaged .88 ± .25 ml/kg/min while the younger children averaged 1.56 ± .37 ml/kg/min. Mean oral dosage requirements also varied with age. Seventy-seven children under age 9 required 24.1 ± 5.5 mg/kg/day of theophylline to maintain therapeutic levels, and no significant correlation with age was observed in this group. Among the 79 children from 9-16 years of age. however, doses averaged 19.4 ± 4.9 mg/kg/day and correlated significantly with age (r = −.32, p < .01). Thus, weight adjusted dosage guidelines for theophylline must be age specific.