Pharmacokinetic study in asthmatic children 5 to 11 years old treated with either a fixed combination of beclomethasone 50 ug/unit dose plus formoterol fumarate 6 ug/unit dose via the NEXT DPI dry powder inhaler or a free combination of Beclomethasone 100 ug DPI and Formoterol 6 ug DPI according to a cross-over design.