There are disclosed systems and methods for isolating and desiccating a portion of a drug delivery tract of a drug delivery apparatus to reduce water vapor content therein are provided. There is provided a metered dose inhaler (100) for delivering aerosolized medicament or other matter to a user. The aerosolized medicament or other matter may be discharged from a discharge passageway (120) within the inhaler into an inhalation passageway (126) for inhalation by a user, and the inhaler comprises a seal member (130) operative to selectively isolate the discharge passageway from the inhalation passageway and external environment during inactivity. The inhaler further comprises a desiccant material (152) arranged to withdraw moisture from the isolated discharge passageway. In other instances, desiccant material may be arranged to withdraw moisture from the discharge passageway of the inhaler without isolating the discharge passage during inactivity.
