Subjects with significant past or present disease which which may affect their safety.

Upper or lower respiratory tract infection within 4 weeks of screening.

History of life threatening asthma, or asthma requiring treatment with oral corticosteroids within 3 months of study.

Patients taking doses of inhaled corticosteroid \>500mcg/day and patients who have changed therapy within 8 weeks of the study.

Patients weighing less than 50kg.

Repeat Doses Of A New Medication (GW642444) In Asthmatic Patients