A review.This article describes the use of nebulizer/atomizer, dry powder inhaler, nasal inhaler and metered-dose aerosol inhaler drugs for inhalation therapy.Drugs administered via the respiratory system (inhalation therapy) can be delivered either orally or nasally.Oral aerosols have been used mainly for the symptomatic treatment of asthma, as well as for the treatment of several other ailments.Foam aerosols, which often are classified sep., consist of three-phase systems in which the liquid propellant, which normally does not exceed 10 to 15 percent by weight, is emulsified with the drug-containing liquidMetered-dose inhalers consist of a pressurized container filled with active ingredient, excipients and propellant, and a metered-dose valve.