Salbutamol in the 1980s. A reappraisal of its clinical efficacy

Critical reappraisal of short-acting bronchodilators for pediatric respiratory diseases

Short-acting bronchodilators are a class of medications commonly used to treat asthma, chronic obstructive pulmonary disease, and other respiratory conditions. The use of these medications has evolved over time as we have gained a better understanding of their effectiveness and safety in the pediatric population. This comprehensive review synthesizes the current understanding of short-acting β2-agonists and short-acting anticholinergics in children. It addresses indications, contraindications, safety considerations, and highlights areas where further research is needed to guide the most effective use of short-acting bronchodilators.

Oral Albuterol Treatment in Three Pediatric Patients with Bradycardia: A Novel Therapy

Clinically significant bradycardia is an uncommon problem in children, but one that can cause significant morbidity and sometimes necessitates implantation of a pacemaker. The most common causes of bradycardia are complete heart block (CHB), which can be congenital or acquired, and sinus node dysfunction, which is rare in children with structurally normal hearts. Pacemaker is indicated as therapy for the majority of children with CHB, and while early mortality is lower in postnatally diagnosed CHB than in fetal CHB, it is still up to 16%. In young children, less invasive transvenous pacemaker systems can be technically challenging to place and carry a high risk of complications, often necessitating surgical epicardial pacemaker placement, which usually entails a median sternotomy. We report three cases of pediatric patients referred for pacemaker implantation for different types of bradycardia, treated at our institution with oral albuterol with therapeutic results that avoided the need for surgical pacemaker implantation at that time.

Docking guided phase display to develop fusion protein with novel scFv and alkaline phosphatase for one-step ELISA salbutamol detection

Introduction

Salbutamol (SAL) is a β2 adrenergic receptor agonist which has potential hazardous effects for human health. It is very important to establish a sensitive and convenient method to monitor SAL.

Methods

Here we introduce a method to combine the information from docking and site specific phage display, with the aim to obtain scFv with high affinity to SAL. First, single chain variable fragment (scFv) antibodies against SAL were generated through phage display. By using molecular docking approach, the complex structure of SAL with antibody was predicted and indicated that H3 and L3 contribute to the binding. Then new libraries were created by randomization specific residues located on H3 and L3 according to the docking results.

Results and discussion

Anti-SAL scFv antibodies with high efficiency were finally identified. In addition, the selected scFv was fused with alkaline phosphatase and expressed in E coli to develop a rapid and low-cost one step ELISA to detect SAL.

Asthma management and control in children, adolescents, and adults in 25 countries: a Global Asthma Network Phase I cross-sectional study

BACKGROUND

Asthma is one of the most common non-communicable diseases globally. This study aimed to assess asthma medicine use, management plan availability, and disease control in childhood, adolescence, and adulthood across different country settings.

METHODS

We used data from the Global Asthma Network Phase I cross-sectional epidemiological study (2015-20). A validated, written questionnaire was distributed via schools to three age groups (children, 6-7 years; adolescents, 13-14 years; and adults, ≥19 years). Eligible adults were the parents or guardians of children and adolescents included in the surveys. In individuals with asthma diagnosed by a doctor, we collated responses on past-year asthma medicines use (type of inhaled or oral medicine, and frequency of use). Questions on asthma symptoms and health visits were used to define past-year symptom severity and extent of asthma control. Income categories for countries based on gross national income per capita followed the 2020 World Bank classification. Proportions (and 95% CI clustered by centre) were used to describe results. Generalised structural equation multilevel models were used to assess factors associated with receiving medicines and having poorly controlled asthma in each age group.

FINDINGS

Overall, 453 473 individuals from 63 centres in 25 countries were included, comprising 101 777 children (6445 [6·3%] with asthma diagnosed by a doctor), 157 784 adolescents (12 532 [7·9%]), and 193 912 adults (6677 [3·4%]). Use of asthma medicines varied by symptom severity and country income category. The most used medicines in the previous year were inhaled short-acting β2 agonists (SABA; range across age groups, 29·3-85·3% participants) and inhaled corticosteroids (12·6-51·9%). The proportion of individuals with severe asthma symptoms not taking inhaled corticosteroids (inhaled corticosteroids alone or with long-acting β2 agonists) was high in all age groups (934 [44·8%] of 2085 children, 2011 [60·1%] of 3345 adolescents, and 1142 [55·5%] of 2058 adults), and was significantly higher in middle-to-low-income countries. Oral SABA and theophylline were used across age groups and country income categories, contrary to current guidelines. Asthma management plans were used by 4049 (62·8%) children, 6694 (53·4%) adolescents, and 3168 (47·4%) adults; and 2840 (44·1%) children, 6942 (55·4%) adolescents, and 4081 (61·1%) adults had well controlled asthma. Independently of country income and asthma severity, having an asthma management plan was significantly associated with the use of any type of inhaled medicine (adjusted odds ratio [OR] 2·75 [95% CI 2·40-3·15] for children; 2·45 [2·25-2·67] for adolescents; and 2·75 [2·38-3·16] for adults) or any type of oral medicine (1·86 [1·63-2·12] for children; 1·53 [1·40-1·68] for adolescents; and 1·78 [1·55-2·04] for adults). Poor asthma control was associated with low country income (lower-middle-income and low-income countries vs high-income countries, adjusted OR 2·33 [95% CI 1·32-4·14] for children; 3·46 [1·83-6·54] for adolescents; and 4·86 [2·55-9·26] for adults).

INTERPRETATION

Asthma management and control is frequently inadequate, particularly in low-resource settings. Strategies should be implemented to improve adherence to asthma treatment guidelines worldwide, with emphasis on access to affordable and quality-assured essential asthma medicines especially in low-income and middle-income countries.

FUNDING

International Union Against Tuberculosis and Lung Disease, Boehringer Ingelheim New Zealand, AstraZeneca, UK National Institute for Health Research, UK Medical Research Council, European Research Council, the Spanish Instituto de Salud Carlos III.

TRANSLATION

For the Spanish translation of the abstract see Supplementary Materials section.

Salbutamol in the Management of Asthma: A Review

Asthma is a common inflammatory disease of the lungs. The prevalence of asthma is increasing worldwide, and the tendency indicates that the number of asthma sufferers will soar in the coming years for several reasons, in particular, the lifestyles we have adopted that expose us to risk factors. Salbutamol is the first selective short-acting β2-agonist (SABA) used as an alternative reliever in the treatment of asthma. Its therapeutic effect is based on its potent smooth muscle relaxant properties, which allow the inhibition of bronchial smooth muscle contraction and subsequent bronchodilation. Salbutamol can be administered orally, intravenously (IV), intramuscularly (IM), subcutaneously, or by inhalation. For this reason, the pharmacokinetic (PK) parameters-absorption, distribution, metabolism, and elimination-are highly diverse and, consequently, the efficacy and adverse effects also differ between each formulation. Here, we review the pharmacological profile of different salbutamol formulations, focusing on their efficacy and adverse effects for its original application, asthma.

Surface plasmon resonance biosensor for the detection of phenylethanolamine A in swine urine

In the present study, an antibody against phenylethanolamine A (PEA) was produced, confirmed, and used in a surface plasmon resonance (SPR)-based measurement. Bovine serum albumin (BSA)-conjugated PEA was linked to nano-gold particles bound to l-cysteine modified on the surface of a Au-NP sensor chip. The concentrations of antigen and antibody were optimized, and the designed biosensor chip was investigated to examine the stability and accuracy of the proposed method. The recovery of PEA ranged from 80.4-93.4% in swine urine samples with spike levels of 5, 10 and 20 ng mL-1, and the relative standard deviations of PEA were less than 2%. PEA analogues, such as clenbuterol, ractopamine, and salbutamol, did not influence the PEA measurement. The developed method could be used to measure PEA in swine urine samples.

Association of human serum paraoxonase-1 with some respiratory drugs

In this study, we investigated the effects of certain respiratory drugs, which are mainly used on human serum paraoxonase-1 (hPON1; EC 3.1.8.1). hPON1 was purified from human serum, with 354.91 fold and 45% yield by using two simple step procedures including, first, ammonium sulfate precipitation, then, Sepharose-4B-l-tyrosine-1-naphthylamine hydrophobic interaction chromatography. SDS-polyacrylamide gel electrophoresis showed a single protein band belonging to hPON1 with 43 kDa. All the pharmaceutical compounds inhibited the PON1 enzyme highly at the micromolar level. The obtained IC₅₀ values for nine different pharmaceutics ranged from 0.219 μM (salbutamol sulfate) to 67.205 μM (montelukast sodium). So, all drugs could be considered as potent hPON1 inhibitors. K_i values and inhibition types were determined by Lineweaver-Burk graphs. While varenicline tartrate and moxifloxacin hydrochloride inhibited the enzyme in a noncompetitive manner, others inhibited it in a mixed manner.

β2-Agonist Induces Net Leg Glucose Uptake and Free Fatty Acid Release at Rest but Not During Exercise in Young Men

OBJECTIVE

The role of selective β2-adrenergic stimulation in regulation of leg glucose uptake and free fatty acid (FFA) balance is inadequately explored in humans. The objective of this study was to investigate β2-adrenergic effects on net leg glucose uptake and clearance, as well as FFA balance at rest and during exercise.

DESIGN

The study was a randomized, placebo-controlled crossover trial where 10 healthy men received either infusion of β2-agonist terbutaline (0.2 to 0.4 mg) or placebo. Net leg glucose uptake and clearance and FFA balance were determined at rest and during 8 minutes of knee extensor exercise using Fick's principle. Vastus lateralis muscle biopsies were collected at rest and at cessation of exercise. The primary outcome measure was net leg glucose uptake.

RESULTS

At rest, net leg glucose uptake and clearance were 0.35 (±0.16) mmol/min and 41 (±17) mL/min (mean ± 95% CI) higher (P < 0.001) for terbutaline than placebo, corresponding to increases of 84% and 70%. During exercise, no treatment differences were observed in net leg glucose uptake, whereas clearance was 101 (±86) mL/min lower (P < 0.05) for terbutaline than placebo. At rest, terbutaline induced a net leg FFA release of 21 (±14) µmol/min, being different from placebo (P = 0.04). During exercise, net leg FFA uptake was not different between the treatments.

CONCLUSIONS

These observations indicate that β2-agonist alters net leg glucose uptake and clearance, as well as FFA balance in humans, which is associated with myocellular β2-adrenergic and insulin-dependent signaling. Furthermore, the study shows that exercise confounds the β2-adrenergic effect on net leg glucose uptake and FFA balance.

Isobaric Tags for Relative and Absolute Quantification (iTRAQ)-Based Untargeted Quantitative Proteomic Approach To Identify Change of the Plasma Proteins by Salbutamol Abuse in Beef Cattle

Salbutamol, a selective β₂-agonist, endangers the safety of animal products as a result of illegal use in food animals. In this study, an iTRAQ-based untargeted quantitative proteomic approach was applied to screen potential protein biomarkers in plasma of cattle before and after treatment with salbutamol for 21 days. A total of 62 plasma proteins were significantly affected by salbutamol treatment, which can be used as potential biomarkers to screen for the illegal use of salbutamol in beef cattle. Enzyme-linked immunosorbent assay measurements of five selected proteins demonstrated the reliability of iTRAQ-based proteomics in screening of candidate biomarkers among the plasma proteins. The plasma samples collected before and after salbutamol treatment were well-separated by principal component analysis (PCA) using the differentially expressed proteins. These results suggested that an iTRAQ-based untargeted quantitative proteomic strategy combined with PCA pattern recognition methods can discriminate differences in plasma protein profiles collected before and after salbutamol treatment.

Structural modulation of gut microbiota in Bama minipigs in response to treatment with a "growth-promoting agent", salbutamol

Even though salbutamol (SAL) had remarkable effects on the enhancement of growth rate and carcass composition in different livestock species such as cattle, pigs, sheep and poultry, it was banned as a growth promoter because of its adverse effects on health. However, the specific mechanism by which salbutamol enhances growth efficiency remains unknown. In this study, Bama pigs were randomly allocated to receive salbutamol (5 mg/kg) for 30 or 60 days and were compared with untreated pigs. Pigs treated with salbutamol demonstrated enhanced growth rates and carcass composition; however, they showed deterioration in blood biochemical indices and organ development. We hypothesized that salbutamol exerts its effects by modulating the composition of the gut microbiota population. The faecal microbiome of pigs was characterized via pyrosequencing of the bacterial 16S rRNA gene. The gut microbiota population analysis showed that salbutamol caused shifts in the microbial composition of less abundant species. Redundancy analysis indicated an increase in abundance of the phylum Bacteroidetes, class Betaproteobacteria, family Christensenellaceae and genus Lactobacillus, and a decreased ratio of the phylum Firmicutes, class Clostridia and genera Ruminococcus, Blautia and Subdoligranulum. In conclusion, our study provided circumstantial evidence that the various effects of salbutamol are caused by gut microbiota modulation, and several potential candidates were identified for SAL detection via the gut microbiota. Our findings provided new insights into the roles of the gut microbiota during salbutamol treatment, and these findings will aid in the screening of alternative strategies for animal health improvement and production enhancement.

Residues of Salbutamol and Identification of Its Metabolites in Beef Cattle

Salbutamol, a selective β₂-agonist, endangers the safety of animal products because of its illegal use in food animals. In this work, residues of salbutamol and its metabolites were investigated to select appropriate targets and marker residues for monitoring the illegal use of salbutamol. Ten metabolites of salbutamol were identified from plasma, urine, liver, and kidney samples; of these, six were newly identified. There were significant differences (P < 0.01) between the parent (nonconjugated) and total (conjugated + nonconjugated) salbutamol concentrations in plasma, urine, liver, and kidney tissues. Salbutamol residues in urine were relatively higher than those in plasma and other internal tissues during the dosing period and were rapidly eliminated from plasma, heart, spleen, and kidney tissues during the withdrawal time. Total salbutamol was identified as more preferable than parent salbutamol as a marker residue, and urine and eye tissues were found to be more suitable as targets for preslaughter and postslaughter monitoring of the illegal use of salbutamol in beef cattle.

Combined inhaled beta-agonist and anticholinergic agents for emergency management in adults with asthma

BACKGROUND

Inhaled short-acting anticholinergics (SAAC) and short-acting beta₂-agonists (SABA) are effective therapies for adult patients with acute asthma who present to the emergency department (ED). It is unclear, however, whether the combination of SAAC and SABA treatment is more effective in reducing hospitalisations compared to treatment with SABA alone.

OBJECTIVES

To conduct an up-to-date systematic search and meta-analysis on the effectiveness of combined inhaled therapy (SAAC + SABA agents) vs. SABA alone to reduce hospitalisations in adult patients presenting to the ED with an exacerbation of asthma.

SEARCH METHODS

We searched MEDLINE, Embase, CINAHL, SCOPUS, LILACS, ProQuest Dissertations & Theses Global and evidence-based medicine (EBM) databases using controlled vocabulary, natural language terms, and a variety of specific and general terms for inhaled SAAC and SABA drugs. The search spanned from 1946 to July 2015. The Cochrane Airways Group provided search results from the Cochrane Airways Group Register of Trials which was most recently conducted in July 2016. An extensive search of the grey literature was completed to identify any other potentially relevant studies.

SELECTION CRITERIA

Included studies were randomised or controlled clinical trials comparing the effectiveness of combined inhaled therapy (SAAC and SABA) to SABA treatment alone to prevent hospitalisations in adults with acute asthma in the emergency department. Two independent review authors assessed studies for inclusion using pre-determined criteria.

DATA COLLECTION AND ANALYSIS

For dichotomous outcomes, we calculated individual and pooled statistics as risk ratios (RR) or odds ratios (OR) with 95% confidence intervals (CI) using a random-effects model and reporting heterogeneity (I²). For continuous outcomes, we reported individual trial results using mean differences (MD) and pooled results as weighted mean differences (WMD) or standardised mean differences (SMD) with 95% CIs using a random-effects model.

MAIN RESULTS

We included 23 studies that involved a total of 2724 enrolled participants. Most studies were rated at unclear or high risk of bias.Overall, participants receiving combination inhaled therapy were less likely to be hospitalised (RR 0.72, 95% CI 0.59 to 0.87; participants = 2120; studies = 16; I² = 12%; moderate quality of evidence). An estimated 65 fewer patients per 1000 would require hospitalisation after receiving combination therapy (95% 30 to 95), compared to 231 per 1000 patients receiving SABA alone. Although combination inhaled therapy was more effective than SABA treatment alone in reducing hospitalisation in participants with severe asthma exacerbations, this was not found for participants with mild or moderate exacerbations (test for difference between subgroups P = 0.02).Participants receiving combination therapy were more likely to experience improved forced expiratory volume in one second (FEV₁) (MD 0.25 L, 95% CI 0.02 to 0.48; participants = 687; studies = 6; I² = 70%; low quality of evidence), peak expiratory flow (PEF) (MD 36.58 L/min, 95% CI 23.07 to 50.09; participants = 1056; studies = 12; I² = 25%; very low quality of evidence), increased percent change in PEF from baseline (MD 24.88, 95% CI 14.83 to 34.93; participants = 551; studies = 7; I² = 23%; moderate quality of evidence), and were less likely to return to the ED for additional care (RR 0.80, 95% CI 0.66 to 0.98; participants = 1180; studies = 5; I² = 0%; moderate quality of evidence) than participants receiving SABA alone.Participants receiving combination inhaled therapy were more likely to experience adverse events than those treated with SABA agents alone (OR 2.03, 95% CI 1.28 to 3.20; participants = 1392; studies = 11; I² = 14%; moderate quality of evidence). Among patients receiving combination therapy, 103 per 1000 were likely to report adverse events (95% 31 to 195 more) compared to 131 per 1000 patients receiving SABA alone.

AUTHORS' CONCLUSIONS

Overall, combination inhaled therapy with SAAC and SABA reduced hospitalisation and improved pulmonary function in adults presenting to the ED with acute asthma. In particular, combination inhaled therapy was more effective in preventing hospitalisation in adults with severe asthma exacerbations who are at increased risk of hospitalisation, compared to those with mild-moderate exacerbations, who were at a lower risk to be hospitalised. A single dose of combination therapy and multiple doses both showed reductions in the risk of hospitalisation among adults with acute asthma. However, adults receiving combination therapy were more likely to experience adverse events, such as tremor, agitation, and palpitations, compared to patients receiving SABA alone.

β-Adrenoreceptor agonists in the management of pain associated with renal colic: a systematic review

OBJECTIVES

To determine whether β-adrenoreceptor agonists are effective analgesics for patients with renal colic through a systematic review of the literature.

SETTING

Adult emergency departments or acute assessment units.

PARTICIPANTS

Human participants with proven or suspected renal colic.

INTERVENTIONS

β-adrenoreceptor agonists.

OUTCOME MEASURES

Primary: level of pain at 30 min following administration of the β-agonist. Secondary: level of pain at various time points following β-agonist administration; length of hospital stay; analgesic requirement; stone presence, size and position; degree of hydronephrosis.

RESULTS

256 records were screened and 4 identified for full-text review. No articles met the inclusion criteria.

CONCLUSIONS AND IMPLICATIONS

There is no evidence to support or refute the proposed use of β-agonists for analgesia in patients with renal colic. Given the biological plausibility and existing literature base, clinical trials investigating the use of β-adrenoreceptor agonists in the acute setting for treatment of the pain associated with renal colic are recommended.

TRIAL REGISTRATION NUMBER

CRD42015016266.

Source discrimination of drug residues in wastewater: The case of salbutamol

Analytical methods used for pharmaceuticals and drugs of abuse in sewage play a fundamental role in wastewater-based epidemiology (WBE) studies. Here quantitative analysis of drug metabolites in raw wastewaters is used to determine consumption from general population. Its great advantage in public health studies is that it gives objective, real-time data about community use of chemicals, highlighting the relationship between environmental and human health. Within a WBE study on salbutamol use in a large population, we developed a procedure to distinguish human metabolic excretion from external source of contamination, possibly industrial, in wastewaters. Salbutamol is mainly excreted as the sulphate metabolite, which is rapidly hydrolyzed to the parent compound in the environment, so this is currently not detected. When a molecule is either excreted un-metabolized or its metabolites are unstable in the environment, studies can be completed by monitoring the parent compound. In this case it is mandatory to assess whether the drug in wastewater is present because of population use or because of a specific source of contamination, such as industrial manufacturing waste. Because commercial salbutamol mainly occurs as a racemic mixture and is stereoselective in the human metabolism, the enantiomeric relative fraction (EFrel) in wastewater samples should reflect excretion, being unbalanced towards one of two enantiomers, if the drug is of metabolic origin. The procedure described involves chiral analysis of the salbutamol enantiomers by liquid chromatography-tandem mass spectrometry (LC-MS-MS) and calculation of EFrel, to detect samples where external contamination occurs. Samples were collected daily between October and December 2013 from the Milano Nosedo wastewater treatment plant. Carbamazepine and atenolol were measured in the sewage collector, as "control" drugs. Salbutamol EFrel was highly consistent in all samples during this three-month period, but a limited number of samples had unexpectedly high concentrations where the EFrel was close to that observed of the un-metabolized, commercially available drug, supporting the idea of an external source of contamination, besides human metabolic excretion. Results showed that, when present, non-metabolic daily loads could be evaluated indicating an average of 4.12g/day of salbutamol extra load due to non-metabolic sources. The stereoselectivity in metabolism and enantiomeric ratio analysis appears to be a useful approach in WBE studies to identify different sources of drugs in the environment, when no metabolic products are present at useful analytical levels.

Development and Application of a Gel-Based Immunoassay for the Rapid Screening of Salbutamol and Ractopamine Residues in Pork

Salbutamol (SAL) and ractopamine (RAC) have been illegally used to promote protein synthesis and to increase the feed conversion rate in livestock. However, the residues of SAL and RAC could cause potential hazards for human health. The Ministry of Agriculture of China banned the use of SAL and RAC as growth promoters. In this paper, we provide detailed information on developing a rapid and sensitive gel-based immunoassay for on-site screening of SAL and RAC residues in pork. The detection time was shortened to 20 min. The limits of detection were 0.5 μg/kg for both SAL and RAC by visual detection, whereas the quantitative gel-based immunoassay enabled the detection of SAL (0.051 μg/kg) and RAC (0.020 μg/kg) in spiked pork samples. The gel-based immunoassay showed promise as a multiplexed immunoassay for on-site surveilling of SAL and RAC residues in pork.

Mechanisms underlying enhancements in muscle force and power output during maximal cycle ergometer exercise induced by chronic β2-adrenergic stimulation in men

The study was a randomized placebo-controlled trial investigating mechanisms by which chronic β2-adrenergic stimulation enhances muscle force and power output during maximal cycle ergometer exercise in young men. Eighteen trained men were assigned to an experimental group [oral terbutaline 5 mg/30 kg body weight (bw) twice daily (TER); n = 9] or a control group [placebo (PLA); n = 9] for a 4-wk intervention. No changes were observed with the intervention in PLA. Isometric muscle force of the quadriceps increased ( P ≤ 0.01) by 97 ± 29 N (means ± SE) with the intervention in TER compared with PLA. Peak and mean power output during 30 s of maximal cycling increased ( P ≤ 0.01) by 32 ± 8 and 25 ± 9 W, respectively, with the intervention in TER compared with PLA. Maximal oxygen consumption (V̇o2max) and time to fatigue during incremental cycling did not change with the intervention. Lean body mass increased by 1.95 ± 0.8 kg ( P ≤ 0.05) with the intervention in TER compared with PLA. Change in single fiber cross-sectional area of myosin heavy chain (MHC) I (1,205 ± 558 μm2; P ≤ 0.01) and MHC II fibers (1,277 ± 595 μm2; P ≤ 0.05) of the vastus lateralis muscle was higher for TER than PLA with the intervention, whereas no changes were observed in MHC isoform distribution. Expression of muscle proteins involved in growth, ion handling, lactate production, and clearance increased ( P ≤ 0.05) with the intervention in TER compared with PLA, with no change in oxidative enzymes. Our observations suggest that muscle hypertrophy is the primary mechanism underlying enhancements in muscle force and peak power during maximal cycling induced by chronic β2-adrenergic stimulation in humans.

Development of an ultrasensitive immunochromatographic assay (ICA) strip for the rapid detection of phenylethanolamine A in urine and pork samples

In this study a one-step immunochromatographic assay based on competitive format was developed for the rapid detection of phenylethanolamine A (PEAA) residues in urine and pork samples. A monoclonal antibody against PEAA was produced from BALB/c mice immunized with the PEAA-BSA conjugate. The results of this qualitative test strip were to be interpreted visually. The visual detection limit (VDL) and threshold level of the optimized immunochromatographic assay for PEAA were 0.1 ng/mL and 0.5 ng/mL, respectively. Cross-reactions with other β-agonists were not significant inhibitions to the performance of the test strip assay. The results from the test strip were in a good agreement with those obtained using a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) assay. The immunochromatographic assay developed here was a useful on-site screening tool that is rapid to use, low in cost, and extremely convenient for the detection of PEAA in urine samples and pork samples.

Pharmacology and therapeutics of bronchodilators

Bronchodilators are central in the treatment of of airways disorders. They are the mainstay of the current management of chronic obstructive pulmonary disease (COPD) and are critical in the symptomatic management of asthma, although controversies around the use of these drugs remain. Bronchodilators work through their direct relaxation effect on airway smooth muscle cells. at present, three major classes of bronchodilators, β(2)-adrenoceptor (AR) agonists, muscarinic receptor antagonists, and xanthines are available and can be used individually or in combination. The use of the inhaled route is currently preferred to minimize systemic effects. Fast- and short-acting agents are best used for rescue of symptoms, whereas long-acting agents are best used for maintenance therapy. It has proven difficult to discover novel classes of bronchodilator drugs, although potential new targets are emerging. Consequently, the logical approach has been to improve the existing bronchodilators, although several novel broncholytic classes are under development. An important step in simplifying asthma and COPD management and improving adherence with prescribed therapy is to reduce the dose frequency to the minimum necessary to maintain disease control. Therefore, the incorporation of once-daily dose administration is an important strategy to improve adherence. Several once-daily β(2)-AR agonists or ultra-long-acting β(2)-AR-agonists (LABAs), such as indacaterol, olodaterol, and vilanterol, are already in the market or under development for the treatment of COPD and asthma, but current recommendations suggest the use of LABAs only in combination with an inhaled corticosteroid. In addition, some new potentially long-acting antimuscarinic agents, such as glycopyrronium bromide (NVA-237), aclidinium bromide, and umeclidinium bromide (GSK573719), are under development, as well as combinations of several classes of long-acting bronchodilator drugs, in an attempt to simplify treatment regimens as much as possible. This review will describe the pharmacology and therapeutics of old, new, and emerging classes of bronchodilator.

Effects of salbutamol on the contractile properties of human skeletal muscle before and after fatigue

AIM

The study examined the effects of an oral acute administration of the β2-agonist salbutamol (Sal) (6 mg) vs. placebo on muscle strength and fatigability in 12 non-asthmatic recreational male athletes in a randomized double-blind protocol.

METHODS

Contractile properties of the right quadriceps muscle were measured during electrical stimulations, i.e. twitch, 1-s pulse trains at 20 (P(20) ) and 80 Hz (P(80) ) and during maximal voluntary isometric contraction (MVIC) before (PRE) and after (POST) a fatigue-producing protocol set by an electromyostimulation (30 contractions, frequency: 75 Hz, on-off ratio: 6.25-20s). In addition, the level of muscle voluntary activation was measured.

RESULTS

In PRE and POST conditions, the peak torque (PT) of twitch, P(80) and MVIC were not modified by the treatment. The PT in POST P(20) was slightly, although not significantly, less affected by fatigue in Sal compared with placebo condition. Moreover, twitch half-relaxation time at PRE was smaller under Sal than under placebo (P < 0.05). No significant changes in the degree of voluntary activation were observed with Sal treatment in PRE or POST condition.

CONCLUSION

  Although these findings did not exclude completely an effect of Sal on peripheral factors of human skeletal muscle, oral acute administration of the β2-agonist Sal seems to be without any relevant ergogenic effect on muscle contractility and fatigability in non-asthmatic recreational male athletes.

Effect of carrier particle shape on dry powder inhaler performance

The aim of this study was to characterise the aerosolisation properties of salbutamol sulphate (SS) from dry powder inhaler (DPI) formulations containing different carrier products. The difference in the elongation ratio (ER) of the different carriers was highlighted. Different set of carriers, namely commercial mannitol (CM), commercial lactose (CL), cooling crystallised mannitol (CCM), acetone crystallised mannitol (ACM) and ethanol crystallised mannitol (ECM) were used and inspected in terms of size, shape, density, crystal form, flowability, and in vitro aerosolisation performance using Multi Stage Liquid Impinger (MSLI) and Aerolizer inhaler device. Solid-state and morphological characterization showed that CM product was in pure β-form having particles with smaller ER (CM: ER=1.62 ± 0.04) whereas ACM and ECM mannitol particles were in pure α form with higher ER (ACM: ER=4.83 ± 0.18, ECM: ER=5.89 ± 0.19). CCM product crystallised as mixtures of β-form and δ-form and showed the largest variability in terms of particle shape, size, and DPI performance. Linear relationships were established showing that carrier products with higher ER have smaller bulk density (D(b)), smaller tap density (D(t)), higher porosity (P), and poorer flow properties. In vitro aerosolisation assessments showed that the higher the ER of the carrier particles the greater the amounts of SS delivered to lower airway regions indicating enhanced DPI performance. Yet, DPI performance enhancement by increasing carrier ER reached a "limit" as increasing carrier ER from 4.83±0.18 (ACM) to 5.89±0.19 (ECM) did not significantly alter fine particle fraction (FPF) of SS. Also, carrier particles with higher ER were disadvantageous in terms of higher amounts of SS remained in inhaler device (drug loss) and deposited on throat. Linear relationship was established (r(2)=0.87) showing that the higher the carrier ER the lower the drug emission (EM) upon inhalation. Moreover, poorer flowability for carrier products with higher ER is disadvantageous in terms of DPI formulation dose metering and processing on handling scale. In conclusion, despite that using carrier particles with higher ER can considerably increase the amounts of drug delivered to lower airway regions; this enhancement is restricted to certain point. Also, other limitations should be taken into account including higher drug loss and poorer flowability.

Effects of acute salbutamol inhalation on quadriceps force and fatigability

INTRODUCTION

Oral beta2-agonist administration improves muscle function in persons without asthma. We performed a double-blind, randomized, controlled crossover study to assess whether acute inhaled salbutamol administration improves muscle strength and fatigability in healthy moderately trained subjects.

METHODS

Quadriceps muscle strength was measured during maximal voluntary contraction (MVC) and femoral nerve magnetic stimulation (potentiated single twitch, TwQpeak) before and after (i) a maximal incremental cycling test (n = 10) and (ii) 50 maximal isometric one-leg extensions (n = 9). Each exercise test was performed on three occasions, after salbutamol (200 and 800 microg) or placebo inhalation.

RESULTS

Before exercise, treatments had no significant effect on MVC [(placebo) 597 +/- 146 N vs (200 microg) 629 +/- 151 N vs (800 microg) 610 +/- 148 N] and TwQpeak [(placebo) 215 +/- 83 N vs (200 microg) 227 +/- 69 N vs (800 microg) 250 +/- 84 N]. Maximal power during cycling and maximal force during leg extensions did not differ between treatments. Treatments had no effect on MVC and TwQpeak reductions at 30 min [MVC: (placebo) -8 +/- 9% vs (200 microg) -9 +/- 7% vs (800 microg) -8 +/- 5%; TwQpeak: (placebo) -29 +/- 13% vs (200 microg) -23 +/- 15% vs (800 microg) -20 +/- 8%] and 60 min [MVC: (placebo) -12 +/- 17% vs (200 microg) -6 +/- 9% vs (800 microg) -8 +/- 8%; TwQpeak: (placebo) -20 +/- 21% vs (200 microg) -19 +/- 23% vs (800 microg) -8 +/- 7%] after cycling. Similarly, reductions in MVC and TwQpeak were not significantly different between treatments at 30 [MVC: (placebo) -11 +/- 9% vs (200 microg) -12 +/- 7% vs (800 microg) -8+/- 16%; TwQpeak: (placebo) -37 +/- 12% vs (200 microg) -33 +/- 20% vs (800 microg) -32 +/- 16%] and 60 min [MVC: (placebo) -10 +/- 11% vs (200microg) -11 +/- 6% vs (800 microg) -8 +/- 20%; TwQpeak: (placebo) -30 +/- 11% vs (200 microg) -28 +/- 24% vs (800 microg) -27 +/- 15%] after leg extensions. Treatments did not modify maximal voluntary activation at any time of the protocol.

CONCLUSION

Acute therapeutic or supratherapeutic doses of inhaled salbutamol have no effect on quadriceps strength, fatigue, and recovery in men without asthma.

beta(2)-Adrenergic agonist administration and strength training

beta(2)-Adrenergic agonists (beta(2)AA) produce myriad effects throughout the human body. Prescribed concurrently with theophylline for the bronchodilatory effects they offer in the treatment of asthma and chronic obstructive pulmonary disease, beta(2)AA actions include many beneficial and adverse changes when administered to animals at supraphysiological doses. Beneficial changes include improved musculoskeletal health and function, which can be maintained because adverse changes are reduced if oral beta(2)AA are given at therapeutic dosages in humans with concurrent resistive exercise administration. Combined oral beta(2)AA-resistive exercise treatments have been shown to produce gains in musculoskeletal health and function in numerous healthy and disuse atrophy human models. The mechanism(s) by which beta(2)AA exert their effects are a function of multiple factors, not the least of which includes the type of model receiving the drug treatment. Combined oral beta(2)AA-resistive exercise treatments in humans showed that adverse effects were greatly reduced when prudent and safer drug administration practices were employed (eg, screening subjects for tolerance before drug treatment). Results from human research trials suggest that administration of the combined treatment improves musculoskeletal function and performance with minimal health risk if proper precautions are followed. A related issue is administration of the combined treatment as an ergogenic aid to athletic performance. Given the results presented in this article, physicians should be wary of potential drug abuse and administer beta(2)AA only under appropriate circumstances when such a treatment is warranted.

Effects of acute salbutamol intake during supramaximal exercise in women

OBJECTIVE

To study the effects of an acute therapeutic oral intake of beta(2) agonist on performance and substrate response during supramaximal exercise in women.

METHODS

12 healthy moderately trained female volunteers performed a Wingate test after ingestion of placebo (Pla) and salbutamol (Sal; 4 mg) according to a double-blind randomised crossover study. Blood samples were collected at rest, at the end of exercise and after 5 (r5), 10 (r10) and 15 (r15) min of passive recovery for adrenocorticotropic hormone (ACTH), growth hormone (GH), insulin, blood glucose and lactate measurements.

RESULTS

Peak power (PP) and mean power (MP) significantly increased whereas time to peak power was significantly shorter with Sal than with Pla (p<0.05). No change was observed in the fatigue index. ACTH was not significantly modified but r15 growth hormone significantly decreased (p<0.05) after the intake of Sal. Both blood INS and blood glucose were significantly increased by the intake of Sal during all the experiments (p<0.01). Blood lactate was significantly increased by the intake of Sal compared with that of Pla (p<0.05) after 10 and 15 min of passive recovery.

CONCLUSION

From these data, acute therapeutic oral intake of Sal seems to induce, irrespective of the subjects' gender, an improvement in performance during a supramaximal exercise--that is, increase in PP and MP. Further studies are necessary to clarify whether the mechanisms involved in the response to intake of Sal are linked to central and/or peripheral pathways.

Autonomic nervous system control of the cardiovascular and respiratory systems in asthma

Patients with asthma have exaggerated bronchoconstriction of their airways in response to certain indirect (e.g. cold air, allergens, dust, exercise) or direct (e.g. inhaled methacholine) stimuli. This 'hyper-reactivity' usually co-exists with airway inflammation, although the pathophysiological mechanisms underlying these changes are not fully understood. It is likely that this hyper-reactivity is associated with abnormal autonomic nervous system (ANS) control. In particular, the parasympathetic (vagal) component of the ANS appears to be implicated in the pathogenesis of asthma. In addition, several studies have suggested the existence of differential alteration in ANS function following exercise in asthmatics compared with non-asthmatic individuals. Several early studies suggested that the altered autonomic control of airway calibre in asthma might be reflected by a parallel change in heart rate. Cardiac vagal reactivity does indeed appear to be increased in asthma, as demonstrated by the cardiac response to various autonomic functions tests. However, other studies have reported a lack of association between bronchial and cardiac vagal tone, and this is in accord with the concept of system-independent ANS control. This review provides a discussion of cardiovascular-autonomic changes associated with either the pathophysiology of asthma per se or with asthma pharmacotherapy treatment. Previous investigations are summarised suggesting an apparent association between altered autonomic-cardiovascular control and bronchial asthma. The full extent of autonomic dysfunction, and its clinical implications, has yet to be fully determined and should be the subject of future investigation.

Speed of onset of bronchodilator response to salbutamol inhaled via different devices in asthmatics: a bioassay based on functional antagonism

AIMS

To evaluate the speed of onset of bronchodilation following salbutamol administered via a metered-dose inhaler with a spacer (pMDI + Volumatic) and a dry-powder inhaler (Diskus), as well as the relative potencies of these devices in asthmatic patients with methacholine-induced bronchoconstriction.

METHODS

Eighteen patients inhaled methacholine (MCh) until FEV(1) decreased by 35% of control. Following administration of placebo, 200 microg salbutamol or 400 microg salbutamol through the pMDI + Volumatic or the Diskus, we calculated the time elapsed from drug administration and the appearance of a 90% increase in post-MCh forced vital capacity (FVC), FEV(1) and volume-adjusted mid-expiratory flow (recovery times). The salbutamol doses to be delivered by the two inhalation devices to achieve similar recovery times and the relative potencies of the devices were calculated by using the 2-by-2 Finney parallel regression method.

RESULTS

For all functional variables, recovery times were significantly (P < 0.01) shorter in pMDI + Volumatic than Diskus trials. The salbutamol doses to be delivered by the Diskus to achieve recovery times for FVC, FEV(1) and volume-adjusted mid-expiratory flow similar to those obtained with 200 microg salbutamol administered via the pMDI + Volumatic were 558 (95% CI 537, 579) microg, 395 (95% CI 388, 404) microg and 404 (95% CI 393, 415) microg, respectively, and corresponded to relative potencies of 2.79 (95% CI 2.68, 2.90), 1.98 (95% CI 1.94, 2.02), and 2.02 (95% CI 1.96, 2.07).

CONCLUSIONS

Administration of salbutamol via the pMDI + Volumatic provides faster reversal of induced bronchoconstriction than via the Diskus. The salbutamol dose targeting the lungs with the pMDI + Volumatic is approximately twice that with the Diskus.

Short term salbutamol ingestion and supramaximal exercise in healthy women

OBJECTIVE

To test the hypothesis that chronic salbutamol intake improves performance during supramaximal exercise and to estimate the effects of this treatment on body composition, bone mass, and metabolic indices in healthy women.

METHODS

Fourteen female volunteers (seven sedentary and seven recreationally trained) performed a 30 second Wingate test with and without salbutamol ingestion (12 mg/day for four weeks) in a random, double blind, crossover design. Blood samples were collected at rest, at the end of the test, and during passive recovery for lactate measurement. Body composition and bone mass were determined by dual energy x ray absorptiometry.

RESULTS

Peak power appeared significantly earlier and was significantly (p<0.05) increased after salbutamol intake in all subjects. There was no difference in total work performed and fatigue indices with salbutamol compared with placebo. No significant alterations in lean or fat body mass and bone variables were observed with salbutamol treatment in either trained or untrained subjects during the trial. In contrast, blood lactate was significantly (p<0.05) increased during the recovery period after salbutamol ingestion compared with placebo.

CONCLUSION

As in men, chronic administration of therapeutic concentrations of salbutamol did not induce an anabolic effect in women but increased maximal anaerobic power. Further studies are necessary to clarify the mechanisms involved.

The correlation of urinary levels of albuterol and its metabolites isomers following inhalation from a dry powder inhaler and in vitro particle size characterisation

This study was designed to analyse the two enantiomers of abuterol in urine after the inhalation of a single dose of racemic albuterol from three dry powder inhalers by human volunteers. Urine samples were collected over 24h and analysed by HPLC-with fluorescence detection. Albuterol and its metabolites in urine could only have resulted from pulmonary absorption because gastrointestinal absorption was prevented. Unchanged albuterol and its conjugated metabolites were detected in the urine of healthy volunteers at much higher levels than in the urine of the asthmatics. Also, the amount of S-(+)-isomer excreted in urine was higher than that of the R-(--)-isomer. These differences did not arise as a consequence of either the formulation or the inter-conversion of two isomers in the urine. There is a relationship between the improvement of mid-expiratory flow (FEF(25-75)) and the amount of R-(--)-albuterol remaining to be excreted. The elimination rate constants of the parent drug in healthy volunteers of both R-(--)- and S-(+)-isomers were higher than those of the respective conjugated metabolites. The mean S/R ratio of the parent drug was about unity initially and increased to about 1.5 in the urine collected between 12 and 24h. The values of S/R ratio of the conjugated metabolites in the healthy volunteers were in the range 1.2-2.4, with the value increasing over the time of collection before reaching a plateau. This also occurred with the asthmatics, but the ratios were higher, in the range of 2.0-4.5. In summary, the urinary level of albuterol following in vivo inhalation was found to correlate with in vitro deposition data from the dry powder inhaler.

Separation and determination of norepinephrine, epinephrine and isoprinaline enantiomers by capillary electrophoresis in pharmaceutical formulation and human serum

A capillary electrophoresis method with ultraviolet (UV) detection was developed and optimized for the enantiomer separation of norepinephrine (NE), epinephrine (EP) and isoprenaline (IP) using dual cyclodextrins (CDs) of 2-hydroxypropyl-beta-CD (HP-beta-CD) and heptakis (2,6-di-o-methyl)-beta-CD (DM-beta-CD) as chiral selectors. Optimal separation was obtained using a running buffer of 50mM phosphate containing 30mM HP-beta-CD and 5mM DM-beta-CD at pH 2.90 and a field strength of 20kV in 45cmx75mum (40cm effective length) uncoated capillary. The UV absorbance detection was set at 205nm. A 0.1% (w/w) polyethylene glycol or 0.1% (v/v) acetonitrile was used to enhance the detection sensitivity. There was a wide and excellent linear calibration graph for each enantiomer in the range 1.0x10(-3) to 1.0x10(-6)M and the detection limit (S/N=3) was found from 8.5x10(-7) to 9.5x10(-7)M. The method has been applied for the determination of isoprenaline in isoprenaline hydrochloride aerosol and to the analysis of serum samples. The recoveries of NE and EP in serum and IP in drug were ranged from 90 to 110%. The relative standard deviations of all the analyte peaks were less than 2.8% for migration time and less than 4.8% for peak area.

Past, present and future--beta2-adrenoceptor agonists in asthma management

The beta-adrenoceptor agonists (beta-agonists) have been used to relieve bronchoconstriction for at least 5000 years. beta-agonists are based on adrenaline and early forms, such as isoprenaline, Lacked bronchial selectivity and had unpleasant side effects. Modern beta-agonists are more selective for the beta2-adrenoceptors (beta2-receptors) located in bronchial smooth muscle and have less cardiotoxicity. Traditional beta2-adrenoceptor agonists (beta2-agonists), such as salbutamol, terbutaline and fenoterol, were characterised by a rapid onset but relatively short duration of action. While valuable as reliever medication, their short duration gave inadequate night-time relief and limited protection from exercise-induced bronchoconstriction. beta2-agonists with longer durations of action, formoterol and salmeterol, were subsequently discovered or developed. When combined with inhaled corticosteroids they improved lung function, and reduced symptoms and exacerbations more than an increased dose of corticosteroids. However, tolerance to the bronchprotective effects of long-acting beta2-agonists and cross-tolerance to the bronchodilator effects of short-acting beta2-agonists is apparent despite use of inhaled corticosteroids. The role of beta2-receptor polymorphisms in the development of tolerance has yet to be fully determined. Formoterol is unique in having both a long-lasting bronchodilator effect (> 12 h) and a fast onset of action (1-3min from inhalation), making it effective both as maintenance and reliever medication. The recent change in classification from short- and long-acting beta2-agonists to rapid-acting and/or long-acting agents reflects the ongoing evolution of beta2-agonist therapy.

Albuterol aids resistance exercise in reducing unloading-induced ankle extensor strength losses

While resistance exercise (REX) reduces ankle extensor (AE) mass and strength deficits during short-term unloading; additional treatments, concurrently administered with REX, are required to attenuate the greater losses seen with longer unloading periods. Subjects performed left leg REX, which otherwise refrained from ambulatory and weight-bearing activity for 40 days, while randomized to a capsule (placebo, albuterol) dosing regimen with no crossover to note whether albuterol helps REX mitigate unloading-induced AE losses. A third group of subjects served as unloaded controls. On days 0, 20, and 40, the following data were collected from the left leg: calf cross-sectional area and AE strength measures. Cross-sectional area was estimated using anthropometric methodology, whereas AE strength data were obtained from eight unilateral calf-press repetitions on an inertial-based REX device. Repeated-measures mixed-factorial 3 × 3 analyses of covariance, with day 0 values as a covariate, revealed group × time interactions for the strength variables eccentric total work (ETW) and average power (EAP). Tukey's honestly significant difference shows REX-placebo subjects incurred significant ETW and EAP losses by day 40, whereas the REX-albuterol treatment evoked strength gains to those same variables without concurrent muscle accretion. Corresponding concentric variables did not display similar changes. Day 40 control data significantly declined for many variables; relative to the REX-albuterol treatment, some losses were significant after 20 days. ETW and EAP gains to unloaded AE may be due to one or more mechanisms. Continued research identifying mechanisms responsible for such changes, as well as the safety of REX-albuterol administration in other models, is warranted.

A Nitric Oxide-Releasing Salbutamol Elicits Potent Relaxant and Anti-Inflammatory Activities

Beta2-adrenoceptor agonists are widely used in the treatment of pulmonary diseases. We have investigated the relaxant and anti-inflammatory activities of NCX-950 (alpha'-[[(1,1-dimethylethy)amino]methyl]-4-hydroxy-1,3-benzenedimethanol nitrate) (a nitric oxide-releasing salbutamol) in human isolated bronchi and on lipopolysaccharide (LPS)-induced acute airway inflammation in mice. NCX-950 (10(-8)-10(-5) M) elicited a relaxation of human isolated bronchi moderately higher than salbutamol, which was reduced by a beta-adrenergic blocking drug, propranolol, but not by an inhibitor of guanylate cyclase, ODQ (1H-[1,2,4]oxadiazolo[4,3-] quinolaxin-1-one). The treatment of mice with NCX-950 (1, 10, and 100 microM aerosol) markedly inhibited the neutrophil influx induced by LPS aerosol in bronchoalveolar lavage (BAL) fluid, whereas salbutamol at equimolar doses elicited a moderate inhibition. Pretreatment of mice with NCX-950 (100 microM) also significantly reduced tumor necrosis factor-alpha, interleukin-6 (IL-6), transforming growth factor-beta, and matrix metalloproteinase-9 release in BAL fluid, whereas salbutamol was ineffective. Propranolol, but not ODQ, suppressed the inhibitory activity of NCX-950 on neutrophil influx and IL-6 release in BAL fluids. A nitric oxide-releasing sildenafil NCX-911 [(5-[2-ethoxy-5-(4-methylpiperidinylsulfonyl)phenyl]-1-methyl-3-n-propyl-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one nitrate)], but not sildenafil (100 microM) also reduced the neutrophil influx following LPS exposure in mice. This study reported that NCX-950 elicits potent relaxant and anti-inflammatory activities compared with salbutamol, and these effects may be mainly due to the activation of the beta2-adrenoceptor rather than the cGMP pathway.

Pharmacology and potential therapeutic applications of nitric oxide-releasing non-steroidal anti-inflammatory and related nitric oxide-donating drugs

This review examines the biological significance, therapeutic potential and mechanism(s) of action of a range of nitric oxide-releasing non-steroidal anti-inflammatory drugs (NO-NSAID) and related nitric oxide-releasing donating drugs (NODD). The slow release of nitric oxide (NO) from these compounds leads to subtle changes in the profile of pharmacological activity of the parent, non-steroidal anti-inflammatory drugs (NSAID). For example, compared with NSAID, NO-NSAID cause markedly diminished gastrointestinal toxicity and improved anti-inflammatory and anti-nociceptive efficacy. In addition, nitroparacetamol exhibits hepatoprotection as opposed to the hepatotoxic activity of paracetamol. The possibility that NO-NSAID or NODD may be of therapeutic benefit in a wide variety of disease states including pain and inflammation, thrombosis and restenosis, neurodegenerative diseases of the central nervous system, colitis, cancer, urinary incontinence, liver disease, impotence, bronchial asthma and osteoporosis is discussed.

Treatment of preterm labor with the oxytocin antagonist atosiban: a double-blind, randomized, controlled comparison with salbutamol

OBJECTIVE

To compare the efficacy and safety of atosiban and salbutamol in the treatment of preterm labor.

STUDY DESIGN

A multicenter, double-blind, double-placebo, randomized, controlled trial. Women (n=241) diagnosed with preterm labor at 23-33 gestational weeks were enrolled and received either atosiban (n=119) or salbutamol (n=122). At randomization, women were stratified by gestational age (< or =28 weeks and >28 weeks). Atosiban (i.v. bolus dose of 6.75 mg, then 300 microg/min for 3h and 100 microg/min for up to 48h) and salbutamol (2.5-45 microg/min) were administered by i.v. infusion for up to 48h. Retreatment with study drug or an alternative tocolytic agent was allowed. Main outcome measures included tocolytic effectiveness which was assessed in terms of the number of women undelivered after 48h and 7 days. Tocolytic efficacy and tolerability were assessed in terms of the proportion of women undelivered and who did not require alternative tocolytic therapy at 48h and 7 days of starting treatment. Safety was assessed in terms of maternal side effects and neonatal morbidity.

RESULTS

Tocolytic effectiveness at 48h was 93.3 versus 95.0% (P=0.67) and after 7 days was 89.9 versus 90.1% (P=0.93) in the atosiban and salbutamol groups, respectively. Tocolytic efficacy and tolerability within 48h was 79.8 versus 75.2% (P=0.15), and after 7 days was 58.8 versus 46.3% (P=0.021) in the atosiban and salbutamol groups, respectively. Maternal adverse events, including serious events, occurred more frequently in the salbutamol group. Neonatal outcomes were comparable between the study groups.

CONCLUSIONS

The oxytocin antagonist atosiban was found to be better tolerated by both mother and fetus than salbutamol, with a comparable neonatal and infant safety profile, and atosiban was as effective as salbutamol in delaying threatened preterm birth. This study supports the clinical use of atosiban in the treatment of preterm labor.

Effects of inhaled salbutamol in exercising non-asthmatic athletes

BACKGROUND

Beta-2 agonists such as salbutamol are used, not only by asthmatic athletes to prevent exercise induced asthma, but also by non-asthmatic athletes as a potentially ergogenic agent. We have investigated whether inhaled salbutamol enhances endurance performance in non-asthmatic athletes.

METHODS

A prospective double blind, randomised, three way crossover design was used to study the effects of 200 microg and 800 microg inhaled salbutamol versus a placebo in 12 trained triathletes. The treatments were compared in three identical cycle ergometer sessions at 85% of the predetermined maximal oxygen uptake. Lung function, endurance time, metabolic parameters (glucose, potassium, lactate, free fatty acid, and glycerol), and psychomotor performance were evaluated.

RESULTS

Neither endurance time nor post-exercise bronchodilation were significantly different between the treatments. Metabolic parameters were affected by exercise but not by treatment.

CONCLUSIONS

Inhaled salbutamol, even in a high dose, did not have a significant effect on endurance performance in non-asthmatic athletes, although the bronchodilating effect of the drug at the beginning of exercise may have improved respiratory adaptation. Our results do not preclude an ergogenic effect of beta2 agonists given by other routes or for a longer period.

Effects of inhaled salbutamol in exercising non-asthmatic athletes

BACKGROUND

Beta-2 agonists such as salbutamol are used, not only by asthmatic athletes to prevent exercise induced asthma, but also by non-asthmatic athletes as a potentially ergogenic agent. We have investigated whether inhaled salbutamol enhances endurance performance in non-asthmatic athletes.

METHODS

A prospective double blind, randomised, three way crossover design was used to study the effects of 200 μg and 800 μg inhaled salbutamol versus a placebo in 12 trained triathletes. The treatments were compared in three identical cycle ergometer sessions at 85% of the predetermined maximal oxygen uptake. Lung function, endurance time, metabolic parameters (glucose, potassium, lactate, free fatty acid, and glycerol), and psychomotor performance were evaluated.

RESULTS

Neither endurance time nor post-exercise bronchodilation were significantly different between the treatments. Metabolic parameters were affected by exercise but not by treatment.

CONCLUSIONS

Inhaled salbutamol, even in a high dose, did not have a significant effect on endurance performance in non-asthmatic athletes, although the bronchodilating effect of the drug at the beginning of exercise may have improved respiratory adaptation. Our results do not preclude an ergogenic effect of β2 agonists given by other routes or for a longer period.

Formoterol in clinical practice--safety issues

While short-acting beta2-agonists are seen as the cornerstone of treatment as relief medication for asthma, current guidelines recommend long-acting beta2-agonists as maintenance therapy in combination with inhaled corticosteroids in patients with moderate to severe asthma, poorly controlled on present treatment. Although evidence has shown that formoterol, with its fast- and long-acting profile, is effective when used both as regular and as-needed therapy in all types of asthma, there has been some concern about the potential of beta2-agonists with long-acting profiles to produce side effects with a longer duration than seen with short-acting beta2-agonists. Also, where formoterol is used as needed, a higher total daily dose would be anticipated than when taken twice daily for regular maintenance therapy and this again has led to some concern. In a number of studies, formoterol has been shown to be well tolerated, and although systemic effects expected with this class of drugs did occur, formoterol had significantly less effect on serum potassium, pulse, blood pressure, cardiac frequency and QT interval compared with terbutaline. In addition, the duration of effects was equivalent to that observed with terbutaline and salbutamol and the relative therapeutic index of formoterol compared with salbutamol was found to be 2.5. Furthermore, studies looking at long-term use of formoterol have shown there is no reduction in bronchodilatory effect, and thus, no development of tolerance. In conclusion, formoterol is well tolerated in high doses, producing side effects typical of its class, but with a duration no longer than occurs with short-acting beta2-agonists. These observations, and the lack of tolerance development, suggest that formoterol may be appropriate treatment for patients with asthma of all types and severities on an as-needed basis or as regular treatment.

The evolution of beta2-agonists

Beta-agonists have been widely used in the treatment of asthma for many years Although concerns have been expressed over their safety based largely upon epidemics of increased mortality in asthmatics associated with high doses of isoprenaline in the 1960s and fenoterol in the 1970s and 1980s, the specific beta2-agonists are vital drugs in asthma management. The short-acting beta2-agonists have an important prophylactic role in the prevention of exercise-induced bronchoconstriction, and are essential in the emergency treatment of severe asthma. However, little if any benefit seems to be derived from regular use of short-acting beta2-agonists and regular or frequent use can increase the severity of the condition. The development of beta2-agonists with long-acting properties, such as salmeterol and formoterol, has provided advantages over short-acting beta-agonists, such as prolonged bronchodilation, reduced day- and night-time symptoms and improved quality of sleep, and has reduced the requirement for short-acting beta2-agonists as relief medication. Both drugs are well tolerated and, when added to inhaled corticosteroids, produce greater mprovement in lung function than increased steroid dose alone. Because of its rapid onset of action, formoterol also has the potential to be used for as-needed bronchodilator therapy in asthma.