Double-Blind MethodClinical Trials as TopicCross-Over StudiesRandom AllocationAsthmaCrossing Over, GeneticPlacebosBlindnessTreatment OutcomeAdministration, OralDrug Therapy, CombinationAdministration, InhalationForced Expiratory VolumeBronchodilator AgentsDrug Administration ScheduleAlbuterolBlind Loop SyndromeAdministration, TopicalTime FactorsPregnenedionesPeak Expiratory Flow Rate