 PEF will be measured as a means of monitoring safety and asthma control. PEF will be measured in triplicate, with additional attempts if necessary. The highest PEF volume is used as the representative value. Two measurements of PEF are made daily, once prior to the first AM dose and once prior to the last PM dose of the study drug. Subject will be standing for PEF measurements. No nose-clips will be needed for PEF. 