Beta2-adrenoceptor agonists

Cockcroft DW. As-needed inhaled beta2-adrenoceptor agonists in moderate-to-severe asthma current recommendations. Treat Respir Med. 2005 4 169-174. 

Sears MR, Lotvall J. Past, present and future—beta2-adrenoceptor agonists in asthma management. Respir Med. 2005 99 152-170. 

The drugs that were developed some 40 years ago as general beta-adrenoceptor agonists have largely fallen into disuse with the development of more selective betai-adrenoceptor agonists (for use in cardiac failure) and beta2-adrenoceptor agonists (for use in airways disease and threatened premature labor). 

The efficacy of long-acting beta2-adrenoceptor agonists in patients with chronic obstructive pulmonary disease remains unclear, but their role in treatment regimens, particularly in comparison with oral theophylline, has been reviewed (1). 

Except for suppression of plasma butjrylchoUnester-ase, the adverse effects of bambuterol are those of a beta2-adrenoceptor agonist and are related to the plasma concentration of terbutaline. Plasma butjrylchoUnester-ase returns to control values about 2 weeks after stopping treatment (SEDA-22,188). 

So, there is no evidence that oral beta2-adrenoceptor agonists cause cardiac failure. The epidemiological study proposing the link is inadequate, and the authors themselves have emphasized the need for prospective, randomized trials. 

Beta2-adrenoceptor agonists are widely used in asthma and have inevitably been associated with a number of problems. Some of these are attributable to the drugs themselves, others to the formulations in which they are given. 

Use of beta2-adrenoceptor agonists in threatened premature labor... 

The adverse effects of the beta2-adrenoceptor agonists when given (as a rule by injection) to arrest premature uterine contractions are very similar to those experienced when the classic drug in the series (salbutamol) is used for other purposes. In the special circumstances of obstetrics, however, there are several particular safety problems. 

Clenbuterol may cause somewhat more adverse effects than some other beta2-adrenoceptor agonists and its long half-life could perhaps explain this. 

Dopexamine, which is related structurally to dopamine, is a potent beta2-adrenoceptor agonist (1). Its reported adverse effects include cases of atrial fibrillation and single instances of supraventricular tachycardia and hypotension. 

Formoterol is a long-acting selective beta2-adrenoceptor agonist that is more potent than salmeterol (1) and has a similar duration of action (12 hours) but a rapid onset of effect similar to that of salbutamol. It is available as a multidose, pressurized aerosol and as a dry powder inhaler, delivering 0.006 or 0.012 mg per dose. The usual dose is 0.012 mg bd. 

Formoterol has been compared with various other beta2-adrenoceptor agonists. 

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