- Medications prior to Screening : Use of the following medications within the defined times prior to Visit 1 (Screening and Run-in Visit): Corticosteroids (Systemic, oral, or depot corticosteroids) (12 Weeks); inhaled corticosteroids(Monotherapy or in combination with a LABA for a minimum of 8 weeks and maintained on a stable dose for 4 weeks prior to Visit 1); SABA(6 hours prior to all spirometry assessments) (Study supplied SABA is permitted); LABA (Oral LABAs, inhaled LABAs or combination products containing inhaled LABAs) (1 day); Theophylline, ketotifen, sodium cromoglycate, nedocromil sodium (1 day); Short-acting anti-muscarinics (12 hours), Long-acting anti-muscarinics (7 days), Potent cytochrome P450 3A4 inhibitors (4 weeks), Leukotriene modifiers (48 hours), Immunosuppressive medication (6 months), Anti- immunoglobulin E (12 weeks); Prescription or over the counter medication that would significantly affect the course of asthma, or interact with sympathomimetic amines such as: anticonvulsants (1 day); Herbal medicines (Prescription or nonprescription drugs, including vitamins, herbal and dietary supplements [including St John's worth] unless in the opinion of the investigator and medical monitor the medication will not interfere with the study procedures or compromise subject safety) (7 days [or 14 days if the drug is a potential enzyme inducer] or five half-lives [whichever is longer]); Chinese traditional medicines (1 day) ; Any other investigational drug (30 days or within five half-lives, whichever is longer).