- Or: a documented increase in FEV1 of >12 % and > 150 mL within 2 hours following inhalation of 400 µg salbutamol MDI within 6 months of screening and an increase in FEV1 of > 6 % and >100 mL within 2h following inhalation of 400 µg salbutamol MDI (via spacer) at the screening visit (in order to allow for potential fluctuations in the response to salbutamol in patients known to be responders to salbutamol)