Pharmaceutics & Novel Drug Delivery Systems

Pulmonary Drug Delivery Systems

Pulmonary delivery has been until now primarily  used for the treatment of respiratory  disease. Recently, the lungs' natural  ability to transfer molecules into the blood  stream has been utilised for delivering  drugs to the systemic circulation. This  method is a non invasive alternative to the  painful injections and can lead to rapid  onset of action and good bioavailability.  Inhalation devices broadly fall into three  categories: Pressurised metered-dose inhalers  (MDIs), nebulisers, and dry powder inhalers (DPIs). MDIs contain drugs as a  solution or a suspension of fine particles  in a liquefied propellant held under high  pressure. The drug is emitted through an  orifice from a metering valve. Nebulizers,  on the other hand, do not require propellants and can generate large quantities of  small droplets capable of penetrating into  the lung. DPI is a device that delivers medication  to the lungs in the form of a dry  powder and requires some procedure to  allow a measured dose of powder to be ready for the patient to take. The drug is  typically held either in a capsule for manual  loading or a proprietary form from inside  the inhaler itself. Once loaded or actuated,  the patient puts the mouthpiece  of the inhaler into their mouth and takes  a deep inhalation, thereby delivering the drug.