Combined cholinergic antagonist and beta 2-adrenoceptor agonist bronchodilator therapy by inhalation

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.

Assessment of the clinical usefulness of nebulised ipratropium bromide in patients with chronic airflow limitation

The effect of adding nebulised ipratropium bromide to bronchodilator treatment was studied in 20 patients with severe chronic airflow limitation. Maintenance theophylline with or without a steroid preparation was continued and comparison made between placebo, nebulised salbutamol, and a combination of nebulised salbutamol and ipratropium. Although the mean FEV1 values showed the combination to produce a small but significant increase in peak bronchodilatation over the effect of salbutamol alone, there were eight patients in whom no clinically useful improvement occurred. The remaining 12 patients did obtain clinically useful improvement in the magnitude or the duration of bronchodilatation (or both) as a result of the added ipratropium. The conclusion is that individual patients with chronic airflow limitation responded to the addition of nebulised ipratropium bromide in a variable way. Patients who could obtain additional benefit from ipratropium need to be identified by an appropriate reversibility study before its inclusion in their bronchodilator treatment.

Bronchodilator responses to nebulised ipratropium and salbutamol singly and in combination in chronic bronchitis

A placebo controlled study compared the magnitude and duration of bronchodilatation produced by nebulised salbutamol (5 mg) and ipratropium (0.5 mg) singly and in combination in twenty patients with chronic bronchitis (mean baseline FEV1 was 33% predicted). The onset of action, of both nebulised salbutamol and ipratropium given singly, occurred within 15 min. Both agents produced a similar degree of bronchodilatation. In combination both the magnitude and duration of the bronchodilatation produced was significantly greater than with either agent alone.

A comparison between a combination of ipratropium bromide plus fenoterol in a single metered dose inhaler (Duovent) and salbutamol in asthma

The efficacy of a single metered dose inhaler containing a combination of fenoterol (100 micrograms/puff) and ipratropium bromide (40 micrograms/puff) has been assessed in 12 asthmatics. We conclude that the bronchodilator effect of 2 puffs of the combination inhaler was significantly greater than that achieved by 2 puffs of salbutamol (100 micrograms/puff).

Effects of ipratropium bromide and fenoterol aerosols in pulmonary emphysema

In patients with radiological evidence of pulmonary emphysema the bronchodilator drugs fenoterol and ipratropium bromide produced a considerable increase in vital capacity and reduction in residual volume. The response to fenoterol was virtually complete 15 minutes after administration, but after ipratropium bromide vital capacity was still increasing at 60 minutes. The change in vital capacity was slightly greater with a combination of the two drugs than with either used alone. Changes in FEV1 and peak flow rate were small.

The addition of an aerosol anticholinergic to an oral beta agonist plus theophylline in asthma and bronchitis. A double-blind single dose study

In two groups of patients, 15 with asthma and 15 with chronic bronchitis, the bronchodilator effects of ipratropium bromide, of fenoterol plus theophylline, and of the combination of the three drugs, were compared using a double-blind, single-dose, placebo-controlled format. Ipratropium bromide caused rapid bronchodilatation which was not significantly different in asthmatic patients and patients with bronchitis (delta FEV1 = .29 L in one hour in asthmatic patients, .18 L in patients with bronchitis). In contrast, fenoterol plus theophylline induced a considerably greater effect in asthmatic patients (delta FEV1 = .41 L in one hour) than in those with bronchitis (delta FEV1 = .07 in one hour). The use of the three drugs in combination compared with ipratropium bromide alone, or fenoterol plus theophylline alone, resulted in a significant additional bronchodilatation in asthmatic patients. In the patients with bronchitis, the triple combination was clearly superior to fenoterol plus theophylline. A similar trend was present in comparing the triple combination to ipratropium bromide, but the difference did not reach statistical significance. There was no evidence of synergism when ipratropium bromide was combined with fenoterol plus theophylline in that the total bronchodilator effect was approximately additive. Asthmatic patients and the physician were able to distinguish the triple combination from placebo. No such ability was demonstrated with respect to those with bronchitis. All three drugs were well tolerated. Side effects were mostly mild, and none was related to the use of ipratropium.

Ipratropium bromide and fenoterol by aerosolized solution

Ipratropium bromide (0.5 mg) and fenoterol (2 mg) produced equivalent peak bronchodilatation between 1 and 2 h after administration to eight patients with chronic partially reversible airways obstruction. The duration of action compared with saline was 6 h for ipratropium and 4 h for fenoterol. Both drugs in combination produced greater bronchodilatation than either drug alone. The increase in FVC was disproportionately greater than FEV1 with both drugs and saline, suggesting relief of obstruction of small airways.

Use of ipratropium bromide in patients with severe airways obstruction

In ten adult patients with severe, partially reversible airflow obstruction due to asthma, with or without co-existent chronic bronchitis, the acute bronchodilator responses of ipratropium bromide (40 micrograms) and terbutaline (500 micrograms) from metered-dose inhalers, atropine methonitrate (2 mg) as a wet aerosol and placebo were compared in a double blind trial. Also the combination of ipratropium bromide and terbutaline aerosols was compared with both ipratropium and terbutaline alone in short-term and long-term studies. In the short-term study, all the drugs produced significant bronchodilatation compared with placebo. The responses to ipratropium bromide and terbutaline alone were not significantly different. The combination of ipratropium bromide with terbutaline did not produce significantly greater changes in the FEV1, SGaw or static lung volume than terbutaline alone. Atropine methonitrate however, produced significantly greater changes of the airway conductance (SGaw) and static lung volumes (TLC and RV) but not FEV1, when compared to ipratropium bromide. When administered over randomised periods of one month each there were no significant differences between the combination of ipratropium bromide and terbutaline and each drug alone in daily airflometer recordings, daily symptom scores or fortnightly spirometry and clinical assessment. It is concluded that ipratropium bromide, in the conventional dose of 40 microgramm by metered-dose inhaler produces safe, effective bronchodilatation. Its effect, however, did not significantly augment that of the beta adrenergic stimulant, terbutaline and was less than that of atropine methonitrate 2 mg by wet aerosol.

Comparison of ipratropium bromide and salbutamol by aerosolized solution

Ipratropium bromide (0.125 mg, 0.25 mg and 0.5 mg) and salbutamol (5 mg) by aerosolized solution produced equivalent peak bronchodilatation between one and two hours after administration to ten patients with chronic partially reversible airways obstruction. The duration of action of the two higher doses of ipratropium bromide (0.25 mg--6 hours; 0.5 mg--5 hours) was significantly greater than salbutamol (4 hours). FVC increases with both drugs and saline were greater than FEV1 increases which may indicate dilatation of small peripheral airways or removal of bronchial mucus from these sites after coughing. A dose of 0.25 mg ipratropium bromide as an aerosolised solution is recommended for clinical use.

Ipratropium bromide: a review of its pharmacological properties and therapeutic efficacy in asthma and chronic bronchitis

Ipratropium bromide is an anticholinergc bronchodilator administered by inhalation. Although producing bronchodilation in most patients with obstructive airways disease, it is somewhat less effective than beta 2-adrenoceptor agonist drugs such as salbutamol or fenoterol in patients with asthma, but is at least as effective as these agents in bronchitis. As with the beta 2-adrenoceptor agonists, the onset of maximum effect with ipratropium (about 1.5 to 2 hours) is slower than with isoprenaline (although significant bronchodilation usually occurs within seconds or minutes of ipratropium inhalation), and the duration of effect (about 4 to 6 hours) is longer. Studies of concomitant use of ipratropium and other agents such as beta 2-adrenoceptor agonists, theophylline, or sodium cromoglycate, have usually shown a greater response in many patients than with single drug therapy, as might be expected from the different mechanisms of action of these groups of drugs. Usual inhaled doses of ipratropium were well tolerated in all studies. Ipratropium thus appears to be a suitable alternative to beta 2-adrenoceptor agonist drugs in patients not fully responding to these agents, and combined therapy with ipratropium and other bronchodilating drugs may prove to be an important area of use in patients failing to respond adequately to a single drug regimen. (nevertheless, in asthma patients in whom a 'non-responsive' state is developing, initiation of corticosteroid therapy should not be delayed). Ipratropium may also be useful in the occasional patient in whom side effects such as palpitations or tremor are troublesome with usual inhaled doses of beta 2-adrenoceptor agonists.