Acute resistant asthma caused by excessive beta-2-adrenoceptor agonist inhalation and reversed by inhalation of beclomethasone

With the aim of devising an improved beta 2-agonist treatment regimen for patients presenting with acute severe resistant asthma, a double-blind, placebo-controlled randomised study of the effect of fenoterol and beclomethasone inhalations was done in 40 patients. Fenoterol inhalations had minimal effect in acute resistant asthma, but significant improvement was obtained when beclomethasone inhalations were given before fenoterol inhalations. Sequential beclomethasone and fenoterol inhalations can therefore be used as a preliminary emergency treatment for these patients.

Nebulized fenoterol causes greater cardiovascular and hypokalaemic effects than equivalent bronchodilator doses of salbutamol in asthmatics

The pulmonary and extrapulmonary effects of two doses of nebulized fenoterol (5 mg) salbutamol (5 mg) and ipratropium bromide (0.5 mg) at 60 min intervals were compared in nine patients with asthma in a double-blind, randomized study. Measurements of heart rate, blood pressure, electromechanical systole (QS2I), QTc interval, FEV1 and plasma potassium were made at baseline and at 15, 30 and 60 min after each nebulization. Both beta-agonists caused significantly greater inotropic (QS2I), chronotropic (HR), electrocardiographic (QTc) and hypokalaemic effects than ipratropium bromide (IB), with fenoterol being more potent than salbutamol. Fenoterol had no greater effect on FEV1 than salbutamol although both were superior to IB. Only the first four subjects had two doses as originally intended, because the second administration of fenoterol resulted in marked cardiovascular effects and hypokalaemia. The observed differences in extrapulmonary effects between fenoterol and salbutamol provide a plausible group of mechanisms which may explain the increased risk of death associated with fenoterol in severe asthmatics.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

[Is fenoterol therapy related to increased asthma mortality?]

Retrospective case-control studies suggest a connection between chronic treatment with fenoterol and other beta-2-agonists and increased mortality from asthma. These studies are extremely difficult to assess from a methodological point of view. They raise important questions, however, and force us to critically reevaluate our present therapeutic approach. In the acute situation, beta-2-agonists might be life-saving, and we must therefore be cautious in readily accepting a causal relationship between beta-2-agonist treatment and death from asthma. Probably, retrospective case-control studies are inadequate to establish a clear-cut association between beta-2-agonist therapy and death from asthma. This will require prospective randomized studies including large asthma populations providing accurate information on both chronic and acute drug treatment, and the end-point is death from asthma.

Asthma. Bronchodilators: new developments

This chapter is concerned with recent controversies and new developments in the area of established bronchodilators, namely beta-agonists, antimuscarinic drugs and methylxanthines. It focuses on the studies concerned with fenoterol and its possible role in asthma deaths in New Zealand, the new long-acting beta-agonists and the place of beta-agonists in the treatment of asthma. The possible reasons for the fact that antimuscarinic drugs have been less effective in general than beta-agonists in asthma are explored and the difficulties of using theophylline in clinical practice and its role in the treatment of asthma are discussed.

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

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

Symptomatic effect of inhaled fenoterol in acute bronchitis: a placebo-controlled double-blind study

The symptomatic effect of inhaled fenoterol, a beta 2-agonist, 0.2 mg 4 times daily for 7 days, was evaluated in 80 patients with acute bronchitis examined at the Chest Clinic, Department of Medicine, University Hospital of Tromsø. Seventy-three patients completed the trial. End-point FEV1 (% predicted) showed a mean increase of 5.1% in the fenoterol group and 0.5% in the placebo group (p = 0.006). The corresponding decrease in total symptom score after one week was 67% and 51%, respectively (p = 0.06). In a subgroup of 35 patients with either bronchial hyper-responsiveness, wheezes on auscultation or FEV1 less than 80% of predicted at entry, a statistically significant difference in reduction of total symptom score in favour of fenoterol was demonstrated on the second day of the trial. No difference was found in the 38 patients with normal lung findings. Fenoterol was useful when objective signs of bronchial involvement was present and may be applicable to the treatment of acute bronchitis.

[A patient with pulmonary edema following use of beta-sympathomimetics (tocolytic agents)]

During her pregnancy (29 weeks) a 29-year-old woman complained of pain in the right upper quadrant of her abdomen. Gallbladder stones were demonstrated by ultrasonography. Because of recurrent pain attacks cholecystectomy was performed. Continuous intravenous tocolytic therapy, fenoterol bromide (Parusisten), was given during and following surgery. Two days after this first laparotomy she underwent a second laparotomy because of unexplained abdominal pain and blood loss. A subhepatic haematoma was found without a specific origin for the blood loss. Shortly after this second operation she developed clinical signs and abnormalities on the chest X-ray compatible with severe pulmonary oedema. She needed artificial ventilation for 15 days. There appears to be a pathophysiological relationship between the development of pulmonary oedema and tocolytic therapy. Probably, pulmonary oedema may develop during tocolytic therapy as a result of several factors such as increased hydrostatic pressure, decreased oncotic pressure and perhaps capillary leakage.