The lungs and drug delivery.

Sir,

We read with interest Patil JS, Sarasija's paper entitled “Pulmonary drug delivery strategies: A concise, systematic review” published in Lung India; 2012 Jan; 29(1):44-9.[1] They expertly reviewed literatures and discussed about the physiological (such as mechanism of epithelial cell transport), technical (focusing on excipients and devices which were used, and techniques of particulate dosage production), and efficacy aspects of novel pulmonary drug delivery. We think if some points were discussed, the review could be more perfect.

Micelle, and also liposome as a composite micelle, is a collection of surfactant molecules composed of a hydrophilic head and a hydrophobic tail in the micelle centre. These structures and also its inverted form are able to carry drug across the cell or other biological membranes without any biologic disturbance or drug destruction. Therefore, their use is rapidly expanding, especially for drug delivery to the lungs.[2] Chitosan, one of the most famous and commonly used micelle, was recently used as nanoparticle to deliver drug to the lungs, especially for drugs with high first pass phenomena such as isoniazid.[3] Also, a sustained delivery to the respiratory system by Chitosan-based spray-dried powders was used safely and also it was recommended for delivering drugs (such as protein-based drugs), which should be delivered to the special cells and it can be an instrumental strategy.[45]

On the other hand, other drug delivering strategies such as transdermal delivery should be considered in this issue. It seems that several problems associated with pulmonary route, which it can be effective on the drug delivery (such as difficulty in use especially for children and other patients with poor co-operation), will be solved if this route be used. Therapeutic dermal patches were widely used for cardiovascular diseases and the drug can reach to the systemic circulation with bypassing the intestinal-hepatic circulation and it can be future strategies to drug delivery. Although using hydrophobic polymers in dermal patch increase its efficacy,[6] further investigations were needed to enhance hydrophobic or hydrophilic drugs to deliver effectively via percutaneous administration.