colloidal particles.

  The Pulmonary route has been conventionally used to treat diseases of the respiratory tract and also non-respiratory tract. The significant research work from the last two decades have exposed that in addition to treating local diseases, a wide range of systemic diseases can be treated by delivering drugs to the lungs. In general inhalable formulations of various drugs have been developed to treat the systemic diseases via the lungs. But the problem with those inhalable formulations is they need repeated doses of drug to control the disease condition, since the inhaled drug cleared rapidly. Therefore new technologies have been investigated, where inhaled particles are capable of controlled release of drug from the lungs. In those nanotechnology based drug delivery systems are being developed as a tremendous field. Nano refers to particles size range of 1-1000nm. An important feature of these technologies is the large geometric size of the particles than normal aerosol solutions, which makes it difficult for the lung macrophages to clear these particles. Therefore it results in longer residence times for the particles in the lungs after delivering the drug to the lungs. The present review discusses about the anatomy and structure of lungs, various conventional formulations for pulmonary delivery, and the various colloidal carriers like liposomes, dendrimers, nanoparticles, which involves the delivering of drugs to lungs.   Key words: targeted drug delivery, pulmonary drug delivery, nanotechnology, colloidal particles.