Comparative bronchodilator responses to atropine and terbutaline in asthma and chronic bronchitis

Anticholinergic agents for chronic asthma in adults

BACKGROUND

Anticholinergic agents such as ipratropium bromide are sometimes used in the treatment of chronic asthma. They effect bronchodilation and have also been used in combination with beta2-agonists in the management of chronic asthma.

OBJECTIVES

To examine the effectiveness of anticholinergic agents versus placebo and in comparison with beta2-agonists or as adjunctive therapy to beta2-agonists.

SEARCH STRATEGY

The Cochrane Airways Group asthma and wheeze database was searched with a pre-defined search strategy. Searches were current as of August 2003. Reference lists of articles were also examined.

SELECTION CRITERIA

Randomised trials or quasi-randomised trials were considered for inclusion. Studies assessing an anticholinergic agent versus placebo or in combination/comparison with beta2-agonists were included. In practice, all beta2-agonists were short acting. Short-term (less than 24 hours duration) and longer-term studies were separated; the latter are reported in this review and the former in the review, "Anticholinergic agents for chronic asthma in adults short term".

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed abstracts for retrieval of full text articles. Papers were then assessed for suitability for inclusion in the review. Data from included studies were extracted by two reviewers and entered into the software package (RevMan 4.2). We contacted authors for missing data and some responded. Adverse effect data were analysed if reported in the included studies.

MAIN RESULTS

The studies analysed were in two groups: those comparing anticholinergics with placebo and those comparing the combination of anticholinergics with short acting beta2-agonists versus short acting beta2-agonists alone. The former group had 13 studies involving 205 participants included in this review, and the latter 9 studies involving 440 patients. Generally methodological quality was poorly reported, and there were some reservations with respect to the quality of the studies. Despite the limited number of studies that could be combined, anticholinergic agents in comparison with placebo resulted in more favourable symptom scores particularly in respect of daytime dyspnoea (WMD -0.09 (95%CI -0.14, -0.04, 3 studies, 59 patients). Daily peak flow measurements also showed a statistically significant improvement for the anticholinergic (e.g. morning PEF: WMD =14.38 litres/min (95%CI 7.69, 21.08; 3 studies, 59 patients). However the clinical significance is small and in terms of peak flow measurements equates to approximately a 7% increase over placebo. The more clinically relevant comparison of a combination of anticholinergic plus short acting beta2-agonist versus short acting beta2-agonist alone gave no evidence in respect of symptom scores or peak flow rates of any significant differences between the two regimes. Again there are reservations with respect to the quality of the information from which these conclusions are drawn.

REVIEWERS' CONCLUSIONS

Overall this review provides no justification for routinely introducing anticholinergics as part of add-on treatment for patients whose asthma is not well controlled on standard therapies. This does not exclude the possibility that there may be a sub-group of patients who derive some benefit and a trial of treatment in individual patients may still be justified. The role of long term anticholinergics such as tiotropium bromide has yet to be established in patients with asthma and any future trials might draw on the messages derived from this review.

Spirometry, bronchodilator test or symptom scoring for the assessment of childhood asthma

The value of spirometry, the bronchodilator test and 2 weeks' symptom scoring for the assessment of the severity of childhood asthma was studied in a series of 65 consecutively referred school-aged asthmatic children, with the diurnal peak expiratory flow (PEF) variability in home recordings serving as a golden standard. The amplitude of the peak expiratory flow rate (PEFR) variation could be best predicted by the baseline forced expiratory volume in 1 s (FEV1) and the past history of the symptom rate, the correlation with FEV1 being -0.48, p < 0.001. Although the baseline forced expiratory flow between 25 and 75% of the forced vital capacity (FEF25-75%) and the responses of FEV1 and FEF25-75% to salbutamol also showed significant correlations with the diurnal PEFR variability (r = -0.43, r = 0.47 and 0.41, p < 0.001, respectively), these variants did not improve the regression model. The baseline FEV1. FEF25-75% and PEFR and their responses to salbutamol also had a slight but statistically significant correlation with the methacholine threshold, but the symptom score on the diary card did not show comparable correlations with either the diurnal PEFR variability or the methacholine threshold (r = 0.09, NS, and r = 0.05, NS, respectively). These results indicate that both baseline lung function and the response to the bronchodilator test correlate with the severity of childhood asthma more appropriately than does the symptom score on a diary card. Since many of these correlations were rather weak, however, the assessment of the severity of childhood asthma cannot be reliably based solely on spirometry in all patients.

A comparison of the effects of anticholinergic and beta 2-agonist and combination therapy on respiratory impedance in COPD

The effects of three different regimens of inhaled bronchodilators on spirometry and respiratory impedance as measured with the technique of forced oscillations were compared in a double-blind crossover study in 22 patients with stable chronic obstructive pulmonary disease (FEV1 less than 70 percent predicted). On three trial days, patients inhaled, in random order, 40 micrograms ipratropium bromide, 200 micrograms fenoterol hydrobromide, or a combination of 40 micrograms ipratropium and 100 micrograms fenoterol from a powder inhaler, followed by a second dose of the same drug after 60 min. The effects were measured at baseline and 20, 40, 60, and 120 min after the first inhalation. No significant decrease in total respiratory resistance at 8 Hz (Rrs [8]) was observed after ipratropium, whereas Rrs (8) decreased significantly 20 min after fenoterol and 40 min after the combination regimen (p less than 0.05). All three studied drugs resulted in a significant increase in the reactance (p less than 0.01) and decrease in resonant frequency. Both fenoterol (delta FEV1 34 percent, p less than 0.0001) and the combination regimen (delta FEV1 38 percent, p less than 0.0001) resulted in a significantly larger increase in FEV1 than ipratropium alone (delta FEV1 17 percent, p less than 0.0001). A second dose of fenoterol and of the combination regimen resulted in a further significant increase in FEV1 after 120 min (p less than 0.05). A second dose of ipratropium did not result in a further significant increase in FEV1. The changes in respiratory impedance were qualitatively similar for all three drug regimens, but larger in absolute terms after fenoterol and the combination regimen than after ipratropium. The similar effect of these drugs on the reactance can be explained by an increase in the capacitance of the respiratory system, and in combination with a decrease in frequency dependence of resistance, by assuming a decrease in peripheral airway resistance.

Comparison of ipratropium bromide and albuterol in chronic obstructive pulmonary disease: a three-center study

Seventy-two subjects who had severe chronic obstructive pulmonary disease and a history of heavy smoking completed a study to compare the effect of single doses of ipratropium bromide (0.036 mg), albuterol (0.18 mg), and placebo on the forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), heart rate, and blood pressure during a period of 6 hours. During initial testing for reversibility, 40 subjects did not demonstrate a 15% increase in FEV1 from baseline after metaproterenol. Ipratropium produced a significantly greater response than albuterol in FEV1 at 3, 4, and 5 hours and in FVC at 1, 2, 3, 4, and 5 hours. For the entire 6-hour period, ipratropium produced a 25% greater response than albuterol in FEV1 and a 50% greater response in FVC. The difference between the two drugs was even greater between 3 and 6 hours. There were no significant differences between the three treatments as regards adverse reactions, heart rate, and blood pressure measurements. In patients who have chronic obstructive pulmonary disease, ipratropium bromide has apparent benefits over beta 2 agonist therapy, including a longer duration of action. Ipratropium may also be effective when beta 2 agonists are not effective.

Response localization of the pharmacological agents histamine and salbutamol along the respiratory system by forced oscillations in asthmatic subjects

The bronchodilating effect of 1 mg and 0.4 mg salbutamol on the impedance of the respiratory system was studied in 25 asthmatic subjects after histamine-induced bronchoconstriction. Histamine caused an increase of respiratory resistance (Rrs) at lower frequencies and a frequency dependence of Rrs. Respiratory reactance (Xrs) decreased at all frequencies after histamine challenge. These changes can be explained by peripheral airway obstruction. Impedance measurements performed 5 min after inhalation of 1 mg and 0.4 mg salbutamol showed a decrease of Rrs values at lower frequencies, a disappearance of the frequency dependence of Rrs, and a significant increase of Xrs values. No significant differences in absolute changes of Rrs and Xrs are observed between the salbutamol regimens. These changes after inhalation of salbutamol can be explained by supposing a predominant action on the peripheral airways.

Intravenous use of glycopyrrolate in acute respiratory distress due to bronchospastic pulmonary disease

A patient with acute respiratory distress secondary to emphysema and reactive airway disease had inadequate tidal volumes with and without endotracheal intubation. Because of the patient's failure to respond to maximal standard bronchodilator therapy and the physical inability to ventilate the patient by manual positive pressure, he received IV glycopyrrolate (0.2 mg) approximately 50 minutes after admission to the ED. The patient's condition immediately improved, as evidenced by the ability to manually ventilate the patient; he developed increased tidal volumes; and he began responding to inhalation therapy. This is the first reported case of IV glycopyrrolate administration for chronic obstructive pulmonary disease or asthma in the literature and demonstrates an instance in which inhalation therapy was ineffective due to low tidal volumes.

Comparison of the anticholinergic bronchodilator ipratropium bromide with metaproterenol in chronic obstructive pulmonary disease. A 90-day multi-center study

The short- and long-term efficacy and safety of an inhaled quaternary ammonium anticholinergic agent, ipratropium bromide, and a beta agonist aerosol, metaproterenol, were compared in 261 nonatopic patients with chronic obstructive pulmonary disease (COPD). The study was a randomized, double-blind, 90-day, parallel-group trial. On three test days-one, 45, and 90-mean peak responses for forced expiratory volume in one second and forced vital capacity and mean area under the time-response curve were higher for ipratropium than for metaproterenol. Clinical improvement was noted in both treatment groups, especially during the first treatment month, with persistence of improvement throughout the remainder of the study. Side effects were relatively infrequent and generally mild; tremor, a complication of beta agonists, was not reported by any subject receiving ipratropium. These results support the effectiveness and safety of long-term treatment with inhaled ipratropium in COPD.

Role of the parasympathetic system in airway obstruction due to emphysema

To study the relative contributions of parasympathetic and sympathetic mechanisms in airway obstruction in patients with emphysema, we gave supramaximal doses of anticholinergic and adrenergic agents in sequence and in combination. Serial doses of one agent were administered to achieve a plateau of bronchodilatation; after that the other agent was administered. The plateau achieved with the anticholinergic agent (atropine methonitrate) was significantly higher than that achieved with the adrenergic agent (salbutamol). When the adrenergic agent was given first, additional bronchodilatation was achieved with subsequent use of the anticholinergic agent. When the anticholinergic agent was given first, no additional bronchodilatation was achieved with subsequent administration of the adrenergic agent. When both agents were given simultaneously, the degree of bronchodilatation was virtually identical to that obtained with the anticholinergic agent alone. Tests sensitive to small-airway and large-airway function and lung volumes gave essentially the same results. Thus, all achievable bronchodilatation was obtained with the anticholinergic agent alone. These results suggest that the two classes of agents produce bronchodilatation through a common cholinergic pathway in emphysema, and support the concept that parasympathetic activity is the dominant reversible component of airway obstruction in this disease.

Effect of inhaled atropine or metaproterenol in patients with chronic airway obstruction and therapeutic serum theophylline levels

Twenty-one patients with stable chronic obstructive pulmonary disease (mean FEV1 = 0.98 L) and high-normal serum theophylline levels (15-20 micrograms/ml) were evaluated in a randomized, double-blind fashion for additional bronchodilator response to aerosolized normal saline, atropine, or metaproterenol. Patients were classified as responders (R; n = 9) or nonresponders (NR; n = 12) to inhaled isoproterenol when they were taking no medications. Atropine and metaproterenol caused a significant additional increase in FEV1 for R (p less than .05), whereas only atropine resulted in a significant increase for NR (p less than .05). For R, the increase due to atropine was significantly greater compared to metaproterenol (p less than .05). We conclude that inhaled atropine (an anticholinergic drug) may be preferable to inhaled metaproterenol (a beta-adrenergic agonist) when additional bronchodilation is needed in patients with chronic obstructive pulmonary disease and high-normal serum theophylline levels.

Atropine and terbutaline aerosols in chronic bronchitis: efficacy and sites of action

To examine the additive properties and the sites of action of inhaled atropine sulfate (0.05 mg/kg of body weight) and terbutaline sulfate (0.005 mg/kg) in patients with chronic airflow obstruction, we tested these aerosols separately and together in a double-blind random sequence. Twelve patients with chronic bronchitis and perennial obstruction of airflow were studied by measuring three indices of efficacy (specific airway conductance [Gaw/VL], the forced expiratory volume in one second [FEV1] and the forced vital capacity [FVC]) and three indices of the site of action within the airway (delta [(Gaw/VL)/FEV1], the difference between the change in forced expiratory flow at 75 percent of vital capacity and the change in forced expiratory flow at 25 percent of vital capacity, and the change in density dependence of maximal airflow at 50 percent of vital capacity). Both atropine and the combination of atropine and terbutaline improved all indices of efficacy significantly more than did terbutaline. With individual exceptions, the addition of terbutaline to atropine improved Gaw/VL but not forced airflow. All measures of site of action suggested an advantage for atropine in relatively proximal airways. These results indicate that combined therapy with beta-adrenergic and anticholinergic bronchodilator drugs is marginally more effective than therapy with atropine alone in these patients and suggest that anticholinergic aerosols dilate larger airways more effectively than the beta-agonists.

Atropine-induced psychosis. An unusual complication of therapy with inhaled atropine sulfate

An acute organic brain syndrome occurred in a patient being treated with inhaled atropine sulfate. Immediate reversal of the patient's mental status was achieved with intravenous administration of physostigmine.

The effect of atropine inhalation in "irreversible" chronic bronchitis

Fifteen patients with chronic bronchitis and airflow obstruction which was not improved by inhalation of isoproterenol (increase in forced expiratory volume in one second [FEV1] less than 15 percent) received an aerosol of atropine sulfate (0.05 mg/kg of body weight), in order to determine their response to an anticholinergic bronchodilator drug. The improvement over initial values for FEV1 at 15 minutes following inhalation of isoproterenol and at 90 minutres following inhalation of atropine averaged 5.9 percent and 19.2 percent, respectively (P less than 0.01). Eleven of 15 patients demonstrated a 15 percent or greater increase in FEV1 following inhalation of atropine, and six subjects demonstrated more than 25 percent improvement. The maximum effect of atropine was observed at or later than 90 minutes following inhalation in nine of 11 patients who were responsive to atropine. Minimal systemic toxic effects resulted from inhalation of atropine, although dryness of the mouth was frequent. In patients with chronic bronchitis, airflow obstruction resistant to isoproterenol may respond to inhalation of an aerosol of atropine sulfate.

Density dependence of expiratory flow and bronchodilator response in asthma

Change in the magnitude of density dependence of the maximal expiratory flow (D/MEF) following inhalation of isoproterenol was used as a test for predicting the long term response to isoproterenol vs atropine in 24 adult patients with longstanding asthma. Eleven subjects showed a decrease in D/MEF manifested by increase in volume of isoflow (VisoV) and/or decrease in Vmax50 Helox/air following isoproterenol inhalation (group 1). Thirteen subjects manifested an opposite response (group 2). Atropine sulphate (0.08 mg/kg) and isoproterenol hydrochloride (2.5 mg) were then administered by inhalation, each four times a day for seven days in a randomized double-blind cross over fashion to all subjects. One of group 1 but ten of group 2 subjects had a greater subjective and objective improvement with atropine than with isoproterenol (P less than .005). An increase in D/MEF following isoproterenol can be used as a test to predict a better response to atropine than to isoproterenol over a one week period. Such a response occurs in almost half of the adult chronic asthmatic patients. The results are consistent with a preferential dilatation of the large airways by atropine.