GSK159802 is a potent, inhaled, long acting selective beta-2-receptor agonist (LABA), which is being developed for once daily treatment of asthma and COPD as part of a combination product with a once daily inhaled corticosteroid and also as a standalone product for the treatment of COPD. Stimulation of the beta-2-agonist in the lung mainly relaxes bronchial smooth muscle cells which results in bronchodilation. Unwanted systemic side effects related with beta-2-agonist treatment such as tachycardia, tremor, hyperglycemia and hypokalemia are limited by local administration and also tend to show tachyphylaxis.