has synergistic action and reduces the frequency of asthma attacks and also makes it less severe. In chronic obstructive pulmonary disease (COPD), LABAs may be used as monotherapy or in combination with corticosteroids. The Torch study demonstrated benefits in terms of quality of life and lung function of salmeterol alone or in combination with inhaled corticosteroids in patients with COPD In exercise-induced bronchospasm monotherapy may be indicated in patients without persistent asthma. LABAs should not be used to treat acute symptoms. Pregnancy and lactation Salmeterol use during pregnancy must be decided based on the risks versus benefits to the mother. There are no well-controlled studies with salmeterol in pregnant women. Some animal studies showed developmental malformation when the mother was given several clinical doses orally. In rats, salmeterol xinafoate is excreted in the milk. However, since there is no data to show excretion of salmeterol in a mother's breast milk, a decision on whether to continue or discontinue therapy should be decided based on the important benefits it provides to the mother. Pregnant and lactating women should consult their doctors before using salmeterol. Side effects Due to its vasodilation properties, the common side effects of salmeterol are dizziness, sinus infection, and migraine headaches. Other side effects muscle tremors, hypokalemia due to direct effect on beta-2 receptors on skeletal muscle. In most cases, salmeterol side effects are minor and either do not require treatment or can easily be treated. Certain side effects, however, should be reported to a healthcare provider immediately. Some of these more serious side effects include very fast heart rate, high blood pressure, and worsening breathing problems. Structure-activity relationship Salmeterol has an aryl alkyl group with a chain length of 11 atoms from the amine. This bulkiness makes the compound more lipophilic and it also makes it selective to β2 adrenergic receptors. History Salmeterol, first marketed and manufactured by Glaxo (now GlaxoSmithKline, GSK) in the 1980s, was released as Serevent in 1990. The product is marketed by GSK under the Allen & Hanburys brand in the UK. In November 2005, the US Food and Drug Administration (FDA) released a health advisory, alerting the public to findings that show the use of long-acting β2 agonists could lead to a worsening of symptoms, and in some cases death. While the use of inhaled LABAs are still recommended in asthma guidelines for the resulting improved symptom control, further concerns have been