Milgrom Henry
Department of Pediatrics, National Jewish Medical and Research Center, University of Colorado at Denver Health Sciences Center, 400 Jackson Street, Denver, CO 80206, USA.
Expert Opin Pharmacother. 2006 Aug;7(12):1659-68. doi: 10.1517/14656566.7.12.1659.
With the exception of levosalbutamol, all of the beta2-agonists that are currently in use are racemic mixtures that are composed in equal amounts of (R)- and (S)-enantiomers. Clinical and mechanistic studies have demonstrated that (R)-salbutamol alone provides the beta2-agonist activity that is needed for the relief of bronchoconstriction, as well as the beta2-adrenergically mediated side effects. (S)-Salbutamol, on the other hand, has minimal binding affinity for the beta2-receptor, indicating that its effects are likely to be mediated through another site. Furthermore, there is evidence that (S)-salbutamol opposes the desirable effects of (R)-salbutamol in the racemic mixture and contributes to the development of characteristic features of asthma, such as airway obstruction, bronchial hyperresponsiveness and airway inflammation. Evidence from clinical studies shows delayed recovery from exacerbation of asthma by patients who are exposed to high concentrations of (S)-salbutamol.
除了左沙丁胺醇外，目前使用的所有β2受体激动剂都是消旋混合物，由等量的（R）-和（S）-对映体组成。临床和机制研究表明，单独的（R）-沙丁胺醇可提供缓解支气管收缩所需的β2受体激动剂活性，以及β2肾上腺素能介导的副作用。另一方面，（S）-沙丁胺醇对β2受体的结合亲和力极小，表明其作用可能通过另一个位点介导。此外，有证据表明，（S）-沙丁胺醇在消旋混合物中会对抗（R）-沙丁胺醇的有益作用，并导致哮喘特征性症状的发展，如气道阻塞、支气管高反应性和气道炎症。临床研究证据显示，接触高浓度（S）-沙丁胺醇的哮喘患者急性加重后的恢复延迟。
