To the Editor.
—Dr Bone1 highlighted some important points regarding the indicated uses of salmeterol xinafoate, a new long-acting inhaled bronchodilator. This selective β2-adrenoceptor agonist is intended for use twice daily as a maintenance therapy and, based on a relatively slower onset of action than short-acting β2-adrenoceptor agonists, should not be used for the treatment of acute asthma symptoms.However, we feel Dr Bone's comments concerning the potential for accumulation and toxicity need clarification. Following the treatment of asthma patients for 2 to 10 months with 42 μg of salmeterol xinafoate twice daily, a single inhaled dose of 42 μg resulted in detectable plasma levels within 5 to 10 minutes and very low peak plasma concentrations (150 pg/mL), consistent with the low systemic exposure expected from an inhaled drug.2 Plasma concentrations determined 12 hours after dosing were close to or below the limit of
Palmer JBD, Oxford JM. Salmeterol Xinafoate in Asthma. JAMA. 1994;272(20):1575. doi:10.1001/jama.1994.03520200031021